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. 2020 Dec 7;99(2):236–249. doi: 10.1111/cge.13869

Clinical application of a phenotype‐based NGS panel for differential diagnosis of inherited kidney disease and beyond

Jiyoung Oh 1, Jae Il Shin 2, Keumwha Lee 2, CheolHo Lee 1, Younhee Ko 3, Jin‐Sung Lee 1,
PMCID: PMC7839754  PMID: 33095447

Abstract

Understanding the genetic causes of kidney disease is essential for accurate diagnosis and could lead to improved therapeutic strategies and prognosis. To accurately and promptly identify the genetic background of kidney diseases, we applied a targeted next‐generation sequencing gene panel including 203 genes associated with kidney disease, as well as diseases originating in other organs with mimicking symptoms of kidney disease, to analyze 51 patients with nonspecific nephrogenic symptoms, followed by validation of its efficacy as a diagnostic tool. We simultaneously screened for copy number variants (CNVs) in each patient to obtain a higher diagnostic yield (molecular diagnostic rate: 39.2%). Notably, one patient suspected of having Bartter syndrome presented with chloride‐secreting diarrhea attributable to homozygous SLC26A3 variants. Additionally, in eight patients, NGS confirmed the genetic causes of undefined kidney diseases (8/20, 40%), and initial clinical impression and molecular diagnosis were matched in 11 patients (11/20, 55%). Moreover, we found seven novel pathogenic/likely pathogenic variants in PKD1, PKHD1, COL4A3, and SLC12A1 genes, with a possible pathogenic variant in COL4A3 (c.1229G>A) identified in two unrelated patients. These results suggest that targeted NGS‐panel testing performed with CNV analysis might be advantageous for noninvasive and comprehensive diagnosis of suspected genetic kidney diseases.

Keywords: Kidney disease, Renal disease, NGS panel, Genetic diagnosis, Copy number variant


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1. INTRODUCTION

Kidney diseases represent a heterogeneous group of disorders, including monogenic disorders, such as autosomal dominant/recessive polycystic kidney disease (ADPKD/ARPKD), as well as complex genetic diseases, such as steroid resistance nephrotic syndrome (SRNS), Alport syndrome, and congenital anomalies of the kidney and urinary tract (CAKUT). 1 Kidney diseases, especially those with a chronic course, can lead to permanent and irreversible deterioration of renal function. Therefore, accurate and prompt diagnosis is essential for improving outcomes for patients with these diseases; however, this can be difficult due to either nonspecific symptoms and signs or clinically silent symptoms in the early stages of disease. Additionally, this is complicated by several systemic diseases or diseases originating from other organs, that can present symptoms similar to those from confined kidney, including various structural abnormalities, electrolyte imbalances, or metabolic acidosis/alkalosis. For example, renal cysts, which are structural abnormalities in the kidney, can also be identified in various multisystemic diseases, such as tuberous sclerosis complex, oral‐facial‐digital syndrome, and coloboma syndrome, as well as ADPKD or ARPKD. 2 , 3 Therefore, diagnosing the precise underlying causes of kidney diseases with nonspecific symptoms using conventional laboratory and imaging diagnostic tools can be challenging.

An invasive procedure, such as renal biopsy, could often be performed to identify the underlying etiology of this disease group; however, it is limited by the range of conditions that it can successfully confirm and is associated with a risk of complications, including bleeding. 4 , 5 , 6 , 7 Moreover, this diagnostic method often fails to uncover a correct diagnosis in very early or late stages of diseases. 1 , 8

According to several reports, 10% of the population with adult chronic kidney disease (CKD) and almost all pediatric patients who progress to end‐stage renal disease are identified as having inherited kidney disease. 9 , 10 , 11 , 12 Therefore, the importance of genetic testing should not be overlooked during the diagnostic workup of kidney diseases. An accurate genetic diagnosis could provide proper treatment options for the patient in the early phase, leading to prevention of the rapid worsening of the disease and playing a pivotal role in selecting relative kidney donors for transplantation or family planning. However, identifying disease‐causing genes is challenging because of the complexity of the genetic background.

The efforts to improve the capabilities of genetic testing have been developed in recent years, and the revolution of next‐generation sequencing (NGS) has enabled cost‐effective simultaneous sequencing of a broad set of candidate genes. Recently, several studies reported the effectiveness of NGS in identifying various genetic factors in inherited kidney diseases, including glomerular nephropathy, steroid‐resistant nephrotic syndrome, and cystic kidney disease. 2 , 13 , 14 , 15 , 16 , 17 However, most studies are limited by only analyzing well‐known causative genes of inherited kidney disease. Additionally, differential diagnoses of diseases originating in other organs, which could result in symptoms and signs mimicking kidney disease, have not been identified. Moreover, almost all of these studies were performed on patients of mainly European descent; therefore, these results might not represent all ethnic populations.

Here, we applied a targeted NGS panel and simultaneous analysis of copy number variation (CNV) to elucidate the genetic causes of suspected genetic kidney diseases in an Asian population. Additionally, we confirmed the feasibility of this diagnostic method for the differential diagnosis of diseases originating from the kidney or another organ but presenting with overlapping symptoms and signs according to the NGS panel. To validate the diagnostic efficacy of this NGS panel, we tested 51 Korean patients with symptoms of kidney disease and suspected of having inherited kidney disease and referred for evaluation to determine possible genetic causes.

2. MATERIALS AND METHODS

2.1. Patient selection and study design

From January 2018 to August 2019, 51 unrelated, genetically undiagnosed patients were enrolled for targeted NGS testing using a comprehensive kidney disease panel developed in the Department of Clinical Genetics at Severance Children's Hospital (Seoul, Korea). All patients had one or more of the following symptoms/signs: proteinuria, hematuria, electrolyte imbalance, metabolic alkalosis/acidosis, or abnormal kidney structure. We retrospectively reviewed the pedigree information, previous medical history, physical examination findings, and any additional investigative results (e.g., ophthalmologic and otology examinations) in the electronic medical records of each patient. Additionally, we collected the available results based on segregation analyses of family members of each patient. This information was collected under anonymity in a routine diagnostic process, and the study protocol was approved by the Institutional Review Board of the Yonsei University Health System (IRB 4‐2019‐0227). Informed consent for the genetic testing was obtained from each patient or their legal guardians if the patient was aged <19 years.

2.2. Panel design

First, we searched for symptoms and signs resembling those observed in genetic kidney diseases using PubMed, Embase, and MEDLINE. Accordingly, we searched for the following symptoms and signs: proteinuria, hematuria, electrolyte imbalance, metabolic alkalosis/acidosis, and abnormal kidney structure. Based on data from the Human Genome Mutation Database (HGMD), Online Mendelian Inheritance in Man (OMIM) database (http://www.ncbi.nlm.nih.gov/omim), and an extensive literature review using PubMed, we extracted and optimized 203 disease‐causing genes (Table 1). The last search was performed on October 10, 2020.

TABLE 1.

Genes (n = 203) included in the panel of kidney diseases

Gene Cytogenic location Inheritance Gene accession number Disease association
ACTN4 19q13.2 AD NM_004924 Glomerulosclerosis, focal segmental, 1
ADAMTS13 9q34.2 AR NM_139025 Thrombotic thrombocytopenic purpura, familial
AGTR1 3q24 AR NM_000685 Renal tubular dysgenesis
AGXT 2q37.3 AR NM_000030 Hyperoxaluria, primary, type 1
AHI1 6q23.3 AR NM_017651 Joubert syndrome 3
ALG8 11q14.1 AR NM_019109 Polycystic liver disease 3 with or without kidney cysts
ALMS1 2p13.1 AR NM_015120 Alström syndrome, retinitis pigmentosa, sensorineural hearing loss
ANKS6 9q22.33 AR NM_173551 Nephronophthisis 16
AP2S1 19q13.32 AD NM_001301076 Hypocalciuric hypercalcemia, type III
APRT 16q24.3 AR NM_000485 Adenine phosphoribosyltransferase deficiency
AQP2 12q13.12 AD/AR NM_000486 Diabetes insipidus, nephrogenic
ARHGDIA 17q25.3 AR NM_001185077 Nephrotic syndrome, type 8
ARL13B 3q11.1‐q11.2 AR NM_182896 Joubert syndrome 8
ARNT2 15q25.1 AR NM_014862 Webb‐Dattani syndrome
ATP6V0A4 7q34 AR NM_020632 Renal tubular acidosis, distal, autosomal recessive
ATP6V1B1 2p13.3 AR NM_001692 Renal tubular acidosis with deafness
AVP 20p13 AD NM_000490 Diabetes insipidus, neurohypophyseal
AVPR2 Xq28

XLR

NM_000054 Diabetes insipidus, nephrogenic; Nephrogenic syndrome of inappropriate antidiuresis
B9D2 19q13.2 AR NM_030578 Joubert syndrome 34
BBS10 12q21.2 AR NM_024685 Bardet‐Biedl syndrome 10
BBS12 4q27 AR NM_152618 Bardet‐Biedl syndrome 12
BBS1 11q13.2 AR/DR Bardet‐Biedl syndrome 1
BBS2 16q13 AR NM_031885 Bardet‐Biedl syndrome 2
BBS4 15q24.1 AR NM_033028 Bardet‐Biedl syndrome 4
BBS9 7p14.3 AR NM_001033604 Bardet‐Biedl syndrome 9
BCS1L 2q35 AR NM_004328 Mitochondrial complex III deficiency, nuclear type 1
BICC1 10q21.1 AD NM_025044 Renal dysplasia, cystic, susceptibility to
BSND 1p32.3

AR

NM_057176 Bartter syndrome, type 4a; Sensorineural deafness with mild renal dysfunction
CA2 8q21.2 AR NM_000067 Osteopetrosis, autosomal recessive 3, with renal tubular acidosis
CA12 15q22.2 AR NM_001218 Hyperchlorhidrosis, isolated
CASR 3q13.3‐q21.1 AD NM_000388 Hypocalcemia, autosomal dominant, with Bartter syndrome
CC2D2A 4p15.32 AR NM_001080522 Joubert syndrome 9
CD151 11p15.5 AR NM_004357 Nephropathy with pretibial epidermolysis bullosa and deafness
CD2AP 6p12.3 AD/AR NM_012120 Glomerulosclerosis, focal segmental, 3
CEP164 11q23.3 AR NM_014956 Nephronophthisis 15
CEP290 12q21.32 AR NM_025114 Bardet‐Biedl syndrome 14; Joubert syndrome 5
CEP41 7q32.2 AR NM_018718 Joubert syndrome 15
CFH 1q31.3 AD/AR NM_000186 Hemolytic uremic syndrome, atypical, susceptibility to, 1
CFHR5 1q31.3 AD NM_030787 Nephropathy due to CFHR 5 days eficiency
CLCN5 Xp11.23 XLR NM_000084 Dent disease; Nephrolithiasis, type I; Proteinuria, low molecular weight, with hypercalciuric nephrocalcinosis
CLCNKB 1p36.13

AR/DR

NM_000085

Bartter syndrome, type 3

Bartter syndrome, type 4b, digenic

CLDN10 13q32.1 AR HELIX syndrome
CLDN16 3q28 AR NM_006580 Hypomagnesemia 3, renal
CLDN19 1p34.2 AR NM_148960 Hypomagnesemia 5, renal, with ocular involvement
CNNM2 10q24.32 AD NM_017649 Hypomagnesemia 6, renal
COL4A1 13q34 AD NM_001303110 Angiopathy, hereditary, with nephropathy, aneurysms, and muscle cramps
COL4A3 2q36.3 AD/AR NM_012120 Alport syndrome
COL4A4 2q36.3 AR NM_000091 Alport syndrome, familiar hematuria
COL4A5 Xq22.3 X‐linked NM_000092 Alport syndrome
COQ2 4q21.22‐q21.23 AR NM_015697 Mitochondrial disease, encephalopathy/isolated nephropathy
COQ6 14q24.3 AR NM_182476 Nephrotic syndrome ± sensorineural deafness
CTNS 17p13.2 AR NM_004937 Cystinosis, nephropathic
CUBN 10p13 AR NM_001081 Imerslund‐Grasbeck syndrome
CYP11B2 3q24.3 AR NM‐000498 Hypoaldosteronism, congenital, due to CMO I deficiency
DGKE 17q22 AR NM_003647 Nephrotic syndrome, type 7
DGUOK 2p13.1 AR NM_080916 Mitochondrial DNA depletion syndrome 3
DMP1 4q22.1 AR NM_001079911 Hypophosphatemic rickets
DHCR7 11q13.4 AR NM_001360 Smith‐Lemli‐Opitz syndrome
EGF 10p13 AR NM_001178130 Hypomagnesemia 4, renal
EGFR 7p11.2 AR Inflammatory skin and bowel disease, neonatal, 2
EHHADH 3q27.2 AD NM_001166415 Fanconi renotubular syndrome 3
EYA1 8q13.3 AD NM_000503 Branchiootorenal syndrome 1, with or without cataracts
FAM58A Xq28 XLD NM_152274 STAR syndrome
FAN1 15q13.3 AR NM_014967 Interstitial nephritis, karyomegalic
FGF23 12p13.32 AD NM_020638 Hypophosphatemic rickets
FN1 2q35 AD NM_212476 Glomerulopathy with fibronectin deposits 2
FRAS1 4q21.21 AR NM_001166133 Fraser syndrome 1
FREM1 9p22.3 AD/AR NM_144966 Bifid nose with or without anorectal and renal anomalies
FREM2 13q13.3 AR NM_207361 Fraser syndrome 2
FXYD2 11q23.3 AD NM_021603 Hypomagnesemia 2, renal
GATA3 10p14 AD NM_001002295 Hypoparathyroidism, sensorineural deafness, and renal dysplasia
GLA Xq22.1 XLR NM_000169 Fabry disease
GLB1 3p22.3 AR NM_000404 Mucopolysaccharidosis type IVB (Morquio)
GLIS2 16p13.3 AR NM_032575 Nephronophthisis 7
GLIS3 9p24.2 AR NM_152629 Diabetes mellitus, neonatal
GNA11 19p13.3 AD NM_002067 Hypocalciuric hypercalcemia, type II
HNF1B 17q12 AD NM_000458 Renal cysts and diabetes syndrome
HPRT1 Xq26.2‐q26.3 XLR NM_000194 HPRT‐related gout, Lesch–Nyhan syndrome
HSD11B2 16q22.1 AR NM_000196 Apparent mineralocorticoid excess
IFT122 3q21.3‐q22.1 AR NM_018262 Cranioectodermal dysplasia 1
IFT140 16p13.3 AR NM_014714 Short‐rib thoracic dysplasia 9 with or without polydactyly
IFT172 2p23.3 AR NM_015662 Short‐rib thoracic dysplasia 10 with or without polydactyly
INF2 14q32.33 AD NM_022489 Glomerulosclerosis, focal segmental, 5
INPP5E 9q34.3 AR NM_019892 Joubert syndrome 1
INVS 9q31.1 AR NM_014425 Nephronophthisis 2, infantile
IQCB1 3q13.33 AR NM_014642 Senior‐Loken syndrome 5
ITGB4 17q25.1 AR NM_000213 Epidermolysis bullosa, junctional, with pyloric atresia
KAL1 Xp22.31 XLR NM_000216 Hypogonadotropic hypogonadism 1 with or without anosmia (Kallmann syndrome 1)
KANK2 19p13.2 AR NM_015493 Nephrotic syndrome, type 16
KCNJ1 11q24.3 AR NM_000220 Bartter syndrome, type 2
KCNJ10 1q23.2 AR NM_002241 SESAME syndrome
KIF7 15q26.1 AR NM_198525 Joubert syndrome 12
LAMB2 3p21.31 AR NM_002292 Pierson syndrome
LCAT 16q22.1 AR NM_000229 Norum disease
LMX1B 9q33.3 AD NM_002316 Nail patella syndrome; FSGS without extrarenal involvement
LRP2 2q31.1 AR NM_004525 Donnai‐Barrow syndrome
LYZ 12q15 AD NM_000239 Amyloidosis, renal
MAFB 20q12 AD NM_005461 Multicentric carpotarsal osteolysis syndrome
MED28 4p15.32 AR NM_025205 nephrotic syndrome
MKKS 20p12.2 AR NM_018848 Bardet‐Biedl syndrome 6
MKS1 17q22 AR NM_017777 Bardet‐Biedl syndrome 13, Joubert syndrome 28
MYH9 22q12.3 AD, association NM_002473 MYH9‐related disease; Epstein and Fechtner syndromes
MMACHC 1p34.1 AR NM_015506 Methylmalonic aciduria and homocystinuria, cblC type
MYO1E 15q22.2 AR NM_004995 Glomerulosclerosis, focal segmental, 6
NEK1 4q33 AD/AR NM_001199397 Short‐rib thoracic dysplasia 6 with or without polydactyly
NEK8 17q11.2 AR NM_178170 Renal‐hepatic‐pancreatic dysplasia 2
NNT 5p12 AR NM_012343 Glucocorticoid deficiency 4, with or without mineralocorticoid deficiency
NOTCH2 1p12 AD NM_024408 Hajdu‐Cheney syndrome
NPHP1 2q13 AR NM_000272 Joubert syndrome 4, Nephronophthisis 1, juvenile
NPHP3 3q22.1 AR NM_153240 Nephronophthisis 3
NPHP4 1p36.31 AR NM_001291593 Nephronophthisis 4
NPHS1 19q13.12 AR NM_004646 Nephrotic syndrome, type 1
NPHS2 1q25.2 AR NM_014625 Nephrotic syndrome, type 2
NR0B1 Xp21.2 XLR NM_000475 Adrenal hypoplasia, congenital
NR3C2 4q31.23 AD NM_000901 Pseudohypoaldosteronism type I, autosomal dominant
NUP214 9q34.13 AR NM_001318324 Encephalopathy, acute, infection‐induced, susceptibility to, 9
OCRL Xq26.1 XLR NM_000276 Dent disease 2, Lowe syndrome
OFD1 Xp22.2 XLR NM_003611 Joubert syndrome 10
PAX2 10q24.31 AD NM_000278 Glomerulosclerosis, focal segmental, 7
PCCA 13q32.3 AR NM_000282 Propionicacidemia
PDSS2 6q21 AR NM_020381 Leigh syndrome
PHEX Xp22.11 XLD NM_000444 Hypophosphatemic rickets, X‐linked dominant
PKD1 16p13.3 AD NM_000296 Polycystic kidney disease 1
PKD2 4q22.1 AD NM_000297 Polycystic kidney disease 2
PKHD1 6p12.3‐p12.2 AR NM_138694 Polycystic kidney disease 4, with or without hepatic disease
PLCE1 10q23.33 AR NM_016341 Nephrotic syndrome, type 3
PLVAP 19p13.11 AR NM_031310 Diarrhea 10, protein‐losing enteropathy type
POMC 2p23.3 AR NM_001035256 Obesity, adrenal insufficiency, and red hair due to POMC deficiency
PTPRO 12p12.3 AR NM_030667 Nephrotic syndrome, type 6
REN 1q32.1 AR NM_000537 Renal tubular dysgenesis
RPGRIP1L 16q12.2 AR NM_015272 Joubert syndrome 7
RRM2B 8q22.3 AR NM_001172477 Mitochondrial DNA depletion syndrome 8A (encephalomyopathic type with renal tubulopathy)
SALL1 16q12.1 AD NM_002968 Townes‐Brocks branchiootorenal‐like syndrome
SALL4 20q13.3 AD NM_001318031 IVIC syndrome
SARS2 19q13.2 AR NM_017827 Hyperuricemia, pulmonary hypertension, renal failure, and alkalosis
SCARB2 4q21.1 AR NM_005506 Action myoclonus‐renal failure syndrome ± hearing loss
SCNN1A 12p13.31 AD NM_001038 Liddle syndrome 3, Bronchiectasis with or without elevated sweat chloride 2
SCNN1B 16p12.2 AD NM_000336 Liddle syndrome 1, Bronchiectasis with or without elevated sweat chloride 1
SCNN1G 16p12.2 AD NM_001039 Liddle syndrome, Bronchiectasis with or without elevated sweat chloride 3
SDCCAG8 1q43‐44 AR NM_006642 Bardet‐Biedl syndrome 16
SIX5 19q13.32 NM_175875 Branchiootorenal syndrome 2
SLC12A1 15q21.1 AR NM_000338 Bartter syndrome, type 1
SLC12A3 16q13 AR NM_000339 Gitelman syndrome
SLC22A12 11q13.1 AR NM_144585 Hypouricemia, renal
SLC26A3 7q22.3‐q31.1 AR NM_000111 Diarrhea 1, secretory chloride, congenital
SLC2A2 3q26.2 AR NM_000340 Fanconi‐Bickel syndrome
SLC34A1 5q35.3 AR NM_003052 Fanconi renotubular syndrome 2
SLC34A3 9q34.3 AR NM_080877 Hypophosphatemic rickets with hypercalciuria
SLC3A1 2p21 AD/AR NM_000341 Cystinuria
SLC4A1 17q21.31 AD/AR NM_000342 Renal tubular acidosis, distal
SLC4A4 4q13.3 AR NM_003759 Renal tubular acidosis, proximal, with ocular abnormalities
SLC5A2 16p11.2 AD/AR NM_003041 Renal glucosuria
SLC6A19 5p15.33 AD NM_001003841 Hyperglycinuria
SLC6A20 3p21.31 AD NM_020208 Hyperglycinuria
SLC7A7 14q11.2 AR NM_001126105 Lysinuric protein intolerance
SLC7A9 19q13.11 AD/AR NM_001126335 Cystinuria
SLC9A3 5p15.33 AR Diarrhea 8, secretory sodium, congenital
SLC9A3R1 17q25.1 AD NM_004252 Nephrolithiasis/osteoporosis, hypophosphatemic, 2
SMARCAL1 2q35 AR NM_014140 Schimke immuno‐osseous dysplasia
SOX17 8q11.23 AD NM_022454 Vesicoureteral reflux 3
SPINK5 5q32 AR NM_001127698 Netherton syndrome
SPINT2 19q13.2 AR NM_001166103 Diarrhea 3, secretory sodium, congenital, syndromic
STAR 8p11.23 AR NM_000349 Lipoid adrenal hyperplasia
TCTN1 12q24.11 AR NM_024549 Joubert syndrome 13
TMEM216 11q12.2 AR NM_016499 Joubert syndrome 2
TMEM237 2q33.1 AR NM_152388 Joubert syndrome 14
TMEM67 8q22.1 AR NM_153704 Joubert syndrome 6, Nephronophthisis 11
TRIM32 9q33.1 AR NM_012210 Bardet‐Biedl syndrome 11
TRPC6 11q22.1 AD NM_004621 Glomerulosclerosis, focal segmental, 2
TTC21B 2q24.3 AD/AR NM_024753 Nephronophthisis 12
TTC8 14q31.3 AR NM_144596 Bardet‐Biedl syndrome 8
UMOD 16p12.3 AD NM_001008389 Uromodulin‐associated kidney disease
UPK3A 22q13.31 UD NM_006953 Involvement renal dysplasia, possible
VIPAS39 14q24.3 AR NM_022067 Arthrogryposis, renal dysfunction, and cholestasis 2
VPS33B 15q26.1 AR NM_018668 Arthrogryposis, renal dysfunction, and cholestasis 1
WDR19 4p14 AR NM_001317924 Nephronophthisis 13, Senior‐Loken syndrome 8
WDR35 2p24.1 AR NM_020779 Short‐rib thoracic dysplasia 7 with or without polydactyly
WNK1 12p13.33 AD NM_018979 Pseudohypoaldosteronism, type IIC
WNK4 17q21.2 AD NM_001321299 Pseudohypoaldosteronism, type IIB
WNT4 1p36.12 AD NM_030761 Mullerian aplasia and hyperandrogenism
WT1 11p13 AD NM_000378 Nephrotic syndrome, type 4; Denys–Drash and Frasier syndrome
XPNPEP3 22q13.2 AR NM_022098 Nephronophthisis‐like nephropathy 1
ZMPSTE24 1p34.2 AR NM_005857 Mandibuloacral dysplasia with type B lipodystrophy
ZNF423 16q12.1 AD/AR 604 557 Joubert syndrome 19; Nephronophthisis 14

Abbreviations: AD, autosomal dominant; AR, autosomal recessive; UD, undetermined.

2.3. DNA preparation

We collected 3 ml of peripheral blood in EDTA tubes from each patient and extracted the genomic DNA from leukocytes using a DNeasy blood and tissue kit (Qiagen, Hilden, Germany) according to manufacturer instructions. The quality of isolated DNA was checked using a Nanodrop spectrophotometer (Thermo Fisher Scientific, Waltham, MA, USA).

2.4. Library preparation, target capture, and DNA sequencing

We constructed a DNA sequencing library using the TruSeq DNA Library Prep Kits protocol according to manufacturer instructions (TruSeq DNA Library Prep Kits,, FC‐121‐2003; Illumina, Carlsbad, CA, USA). Briefly, DNA in each sample was sheared to 250bp sequences, tagged, and then purified according to fragment size with magnetic beads (AMPure XP, Beckman Coulter, IN, USA). We subsequently performed repair, phosphorylation, and adenylation of the 3′ ends and isolated the precaptured amplified 300‐ to 500‐bp fragments. We then performed targeted sequence, up to 15 bp from the exon of the target genes based on hg19, capture according to TruSeq Custom Enrichment Kit protocol (FC‐123‐1096, Illumina). DNA sequencing was performed on a V2 flow cell using MiSeq sequencer (Illumina), generating 150 bp paired‐end reads. Image analysis and base calling were performed using the Illumina pipeline. The yield of each DNA sample averaged 2 GB of raw data with a 150‐fold mean sequencing depth of the targeted regions. 18 , 19 Sequenced reads were mapped to the human reference genome (GRCh37), and sequencing alignment was performed using the Burrows‐Wheeler Aligner software package. 20

2.5. CNV analysis

For CNV detection, we applied ExomeDepth with default parameters. 21 ExomeDepth uses a robust model of the read count data to call CNVs by comparing the test exome data to a matched optimized‐aggregate reference set, which is built with combined exomes from the same batch to maximize the power to handle technical variability between samples. This method was applied to the targeted NGS sequencing data sets to detect pathogenic CNVs, and the identified CNVs were confirmed through multiplex ligation‐dependent probe amplification or real‐time quantitative PCR (RT‐qPCR).

2.6. Sanger sequencing and RT‐qPCR

We performed Sanger sequencing for validation and segregation analysis of variants detected by NGS testing. RT‐qPCR was performed for segregation analysis of CNVs using primers designed according to the oligonucleotide sequences of the variants.

2.7. Interpretation and analysis of the detected variants

We examined the NGS data and prioritized DNA variants according to clinical relevance using the following parameters: (1) sequence quality; (2) allele frequency (according to the Exome Aggregation Consortium [ExAC], dbSNP database, and Korean Reference Genome Database [KRGDB; http://coda.nih.go.kr/]); and (3) presence in HGMD, OMIM, dbSNP, or ClinVar. Real or possible damage of variants was predicted using in silico prediction algorithms, including Polymorphism Phenotyping version 2 (PolyPhen‐2) and Sorting Tolerant from Intolerant (SIFT; https://sift.bii.a-star.edu.sg/). After compressive analysis of all results, we classified the identified variants into a five‐tier system as pathogenic (P), likely pathogenic (LP), variant of unknown significance (VUS), likely benign, or benign according to the American College of Medical Genetics and Genomics (ACMG) guidelines. 22 According to the inheritance pattern of the disease, we considered results positive if one or two P/LP variants in one disease‐related gene was identified according to the inheritance patterns of diseases. If only a VUS or one P/LP variant was detected in a gene with an autosomal recessive (AR) inheritance pattern, we considered the result nondiagnostic. We reported cases without any VUS or P/LP as negative results.

3. RESULTS

3.1. Patient characteristics

A total of 51 unrelated patients were included in this study (median age: 11.6 years [range: 0–46 years]). Among these, 36 (70.6%) were male, and 15 (29.4%) were female. Five patients (9.8%) had a family history related to kidney disease, and three (5.9%) had undergone renal biopsy due to hematuria before the NGS panel test. The reasons for referral were as follows: structural abnormalities in kidneys detected by computed tomography or sonogram in 16 patients, urinalysis abnormalities in 21 patients, electrolyte imbalances in 12 patients, and renal failure in two patients (Table 2).

TABLE 2.

The clinical causes for using NGS in the renal disease panel test

Reasons for NGS Patient number (n)
Structural abnormalities in kidney 16
Polycystic kidney disease 13
Medullary sponge kidney 1
Renal agenesis 1
Bilateral hydronephrosis 1
Urinalysis abnormality 21
Proteinuria 7
Hematuria 11
Proteinuria and hematuria 3
Electrolyte imbalance 12
Renal failure 2
Total 51

Abbreviation: NGS, next‐generation sequencing.

3.2. Diagnostic yield of NGS

In total, the final diagnostic yield was 39.2% (20/51), which included the diagnostic group when P/LP variants or CNV abnormalities in our NGS panel test matched the symptoms of patients. The final molecular diagnosis confirmed by our targeted NGS panel classified patients into the following diseases: four patients with ADPKD, one patient with ARPKD, three patients with Alport syndrome, one patient with hyperoxaluria type 1, three patients with Bartter syndrome, two patients with Gitelman syndrome, one patient with SLC4A1‐associated renal tubular acidosis, and one patient with congenital chloride secretory diarrhea. Moreover, we identified four patients exhibiting dysmorphic features and global delayed development in addition to several renal cysts in both kidneys with CNV abnormalities on chromosome (1p36 [2 patients] and 17q12 [2 patients]). Nondiagnostic results were showed for 31 patients with VUSs only, as well as for four patients with only one P/LP variant in the disease gene with an AR‐inheritance trait.

The first clinical symptoms of the diagnosed patients were as follows: urinalysis abnormality, including hematuria or proteinuria (4/21; 19.0%), structural abnormalities in the kidney (9/16; 56.3%), and electrolyte imbalances (7/12; 58.3%). The details of the patients confirmed by molecular diagnosis are summarized in Table 3.

TABLE 3.

Clinical and genetic data of patients in whom disease‐causative gene variants were identified

ID Gender Age Fx Clinical presentation‐renal Clinical presentation‐extrarenal Final diagnosis Gene Inheritance Sequence variant ACMG class Zygosity
Patients referred for cystic kidney disease
01 M 3 m N Several renal cysts, both kidney

Sensorineural hearing loss, Rt.

Atrial septal defect

Umbilical hernia

1p36.32 microdeletion syndrome 1p36.32 microdeletion Hetero
02 F 11 y N Multiple renal cysts, Metabolic acidosis Delayed development epilepsy 1p36 microdeletion syndrome 1p36 microdeletion Hetero
03 F 2 y N Multiple renal cysts, Delayed development 17q12 microdeletion syndrome 17q12 microdeletion Hetero
04 M 6 y N Multiple renal cysts, Nephronophthisis Delayed development 17q12 microdeletion syndrome 17q12 microdeletion Hetero
05 M 1 m N Multiple renal cysts with variable size Decrease kidney size Atrial septal defect ADPKD PKD1 AD c.5303C>A, (p.Thr1768Asn) 4 Hetero
ID Gender Age Fx Clinical presentation‐Renal Clinical presentation‐Extrarenal Final diagnosis Gene Inheritance Sequence variant ACMG class Zygosity
06 M 18 y Y A hemorrhagic component in the multiple renal cysts, both kidney ADPKD PKD1 AD c.975T>G (p.Tyr325Ter) a 4 Hetero
07 F 50 y N

Multiple renal cysts, both kidney

Chronic renal failure

Liver cyst ADPKD PKD1 AD c.8056C>T (p.Gln2686Ter) 5 Hetero
08 F 42 y N Multiple renal cysts, both kidney Liver cyst ADPKD PKD1 AD c.12060C>A (p.Cys4020Ter) a 4 Hetero
09 F 5 d N Pulmonary hypoplasia, Polycystic dysplastic kidney ARPKD PKHD1 AR

c.4879G>T (p.Val1627Phe)(p) a

c.11212_11213delAT (p.lle3738SerfsTer19)(m) a

4

5

Compound hetero
Patients referred for hematuria +/− proteinuria
10 F 7 y Y Recurrent HU Asthma, atopic dermatitis Alport syndrome COL4A3 AD, AR c.417delG (p.Thr140HisfsTer13) a 4 Hetero
11 F 21 y N

Recurrent HU

GBM irregularity, suggestive of hereditary nephritis

Sensorihearing loss, both Alport syndrome COL4A3

AD, AR

c.1029 + 1G>A a 4 Hetero
12 M 4 y N Hematuria Alport syndrome COL4A4 AD, AR

c.2084G>A (p.Gly695Asp)(p)

c.1327_1344del (p.Pro444‐Leu449del)(m)

4

5

Compound hetero
13 F 5 y N Hematuria, nephrolithiasis Short stature Hyperoxaluria type1 AGXT AR c.331 T>C (p.Arg111Ter) 5 Homo
ID Gender Age Fx Clinical presentation‐Renal Clinical presentation‐Extrarenal Final diagnosis Gene Inheritance Sequence variant ACMG class Zygosity
Patients referred for electrolyte imbalance
14 M 4 y N

polyhydramnios Hx.

Hypokalemia

Bartter syndrome CLCNKB AR

c.371C>T (p.Pro124Leu)(p)

Exon 4 del(m) b

5 Compound hetero
15 F 27 y N

Hypokalemia

Hypochloremia

Hearing impairment tremor Bartter syndrome CLCNKB AR

Exon 1–14 del(p) b

c.1830G>A (p.Trp610Ter)(m)

5 Compound hetero
16 M 15 y N Hypokalemia Hearing impairment tremor Bartter syndrome SLC12A1 AR

c.888delG (p) a

c.1522G>A (p.Ala400Thr) (m)

5

4

Compound hetero
17 F 10 y N Hypokalemia Hypomagnesemia Gitelman syndrome SLC12A3 AR

c.1664C>T (p.Ser555Leu)(p)

c. 2186G>A (p.Gly741Arg)(m)

5

5

Compoundhetero
18 M 23 y N Hypokalemia Dystonia, tremor Gitelman syndrome SLC12A3 AR

c.1919A>G (p.Asn640Ser)(p)

c.1868T>C (p.Leu623Pro)(m)

5

5

Compound hetero
19 F 2 y Y Renal tubular acidosis SLC4A1‐associated renal tubular acidosis SLC4A1 AD c.1765C>T (p.Arg589Cys) 5 Hetero
20 M 11 m N

Hypokalemic alkalosis

Diffusely bilateral renal enlargement with increased cortical echogenicity

Colon segmental resection, d/t colon ischemia Congenital secretory diarrhea, chloride type SLC26A3 AR c.2063‐1G>T (p,m) 4 Homo

Abbreviations: ACMG, American College of Medical Genetics and Genomics; AD, autosomal dominant; AR, autosomal recessive; Fx, family history; F, female; GBM, glomerular basement membrane; Hetero, heterozygous; HU, hematuria; M, male; m, maternal; PU, proteinuria; p, paternal.

a

Novel pathogenic/likely pathogenic variant.

b

Novel exonal deletion.

Among five patients with related familial medical histories, three harbored pathogenic variants associated with their symptoms. Their final diagnosis was ADPKD (one patient), Alport syndrome (one patient), and SLC4A1‐associated distal renal tubular acidosis (one patient). Among the three patients who had undergone renal biopsy due to hematuria before the NGS panel test, one was determined to have one novel LP variant in COL4A3, and two were found to have the same VUS in COL4A3, which was known to be associated with Alport syndrome. These results were consistent with their histological diagnosis.

3.3. Detection of genetic variants and CNVs

Targeted NGS analysis identified 169 variants in 84 genes, with every patient having at least one variant. On average, we detected 2.0 variants, with a maximum of 12 per patient. We detected 27 P/LP variants of 10 genes in 24 patients. Of these variants, 18 (66.7%) had been formerly reported as P/LP, whereas 9 (33.3%) had not yet been reported at the time of our investigation. The mutational types of these 27 P/LP variants were as follows: 11 missense variants, six nonsense variants, three frameshift, three small insertion/deletions, two exonal deletions, and two splicing errors. The most frequently detected P/LP variants were observed in PKD1 (n = 4; 14.8%), CLCNKB (n = 4; 14.8%), and SLC12A3 (n = 4; 14.8%).

Additionally, all patients harbored one or more VUS, with 142 VUSs detected in 70 genes. Among these VUSs, the most frequently involved genes were PKD1 (n = 15; 10.6%), PKHD1 (n = 6; 4.2%), and ALMS1 (n = 6; 4.2%). Additionally, we detected five heterozygous CNVs in five patients, although only two of the CNVs (the 1p36 and 17q12 microdeletions) found in four patients were revealed as pathogenic according to the phenotype of the patients, segregation analysis, and our literature review.

3.4. Novel variants

Among the 20 patients with confirmed disease according to our molecular diagnosis, seven novel variants in seven patients absent from population databases and our in‐house database were identified. Moreover, two novel exonal deletions were identified in CLCNKB for two patients (Patient 14 [exon 4 deletions] and Patient 15 [exon 1–14 deletion]).

Among patients with ADPKD with multiple renal cysts, two novel LP variants of PKD1 were identified, with both were shown to be nonsense variants (Patient 6 [p.Tyr325Ter] and Patient 8 [p.Cys4020Ter]). Further, a 5 day old patient with ARPKD and presenting with polycystic dysplastic kidney disease and hypoplastic lung was found to carry two novel P/LP novel variants in PKHD1. One was a paternally inherited missense LP variant (p.Val1627Phe), whereas the other was a maternally inherited frameshift P variant (p.lle3738SerfsTer19).

In the two patients with Alport syndrome, we detected two different novel P/LP variants of COL4A3. Patient 10, a 7‐year‐old girl, showed recurrent hematuria, and her genetic investigation revealed a paternally inherited P variant (p.Thr140HisfsTer13) in COL4A3. Her father also had a history of nephritis and was diagnosed with Alport syndrome after genetic testing. Additionally, Patient 11 presented with recurrent hematuria and sensory hearing loss and was revealed to have a novel LP variant in COL4A3 that could cause a splicing error (1029 + 1G>A).

Further, we detected a novel P variant (c.888delG) of SLC12A1 in a 15‐year‐old boy with recurrent hypokalemia and symptoms of hearing impairment and tremor. His genetic testing showed a paternally inherited novel variant (c.888delG) combined with a maternally inherited missense P variant (p.Ala400Thr) previously reported in SLC12A1. Accordingly, he was diagnosed with Bartter syndrome based on these results.

3.5. Noteworthy VUSs

Notably, we identified a meaningful VUS in the COL4A3 gene of two unrelated patients (patients 21 and 22). This missense variant was clinically classified as a VUS in a well‐defined disease gene of Alport syndrome (c.1229G>A, p.Gly410Glu) according to ACMG guidelines. Patients 21 and 22 were presenting with proteinuria and hematuria since her 20s and the age of 5. Their renal pathologic findings revealed an irregular thickening of the GBM. Based on the clinical symptoms and biopsy findings, they were clinically suspected of having Alport syndrome. Their NGS panel testing identified the same heterozygous VUS (c.1229G>A, p.Gly410Glu) in COL4A3, with Sanger sequencing confirming the detected variant. The variant was absent from public genome databases (ExAC, 1000 Genomes data, and our in‐house database), and the structure and function of the protein were predicted as likely damaged according to Polyphen2 (PPH2 score: 1.0). The altered residue was revealed to be highly conserved across vertebrate species. Given that this variant was consistently identified in two unrelated patients with highly suspected Alport syndrome from their clinical symptoms and pathological results, along with the results of variant analysis, this suggested a high probability of being reclassified as an LP/P variant. Although further analyses of the genetic consequences based on the family members were recommended to assess the exact pathogenic indication of this VUS, these tests could not be conducted due to lack of agreements by the family members of the patients (Table 4).

TABLE 4.

Clinical and genetic data of patients in whom a noteworthy VUS was identified

ID Gender Age Fx Clinical presentation‐Renal Clinical presentation‐Extrarenal Final diagnosis Gene Inheritance Sequence variant ACMG class Zygosity
Patients referred for hematuria +/− proteinuria
21 F 36 y N HU/ PU since 20′ irregular thickening of GBM Alport syndrome COL4A3 AD, AR c.1229G>A (p.Gly410Glu) 3 Hetero
22 F 15 y N Consistent HU irregular thickening of GBM Alport syndrome COL4A3 AD, AR c.1229G>A (p.Gly410Glu) 3 Hetero

Abbreviations: ACMG, American College of Medical Genetics and Genomics; AR, autosomal recessive; Fx, family history; F, female; GBM, glomerular basement membrane; Hetero, heterozygous; HU, hematuria; M, male; m, maternal; PU, proteinuria; p, paternal; VUS, variant of uncertain significance.

3.6. Correlation between clinically suspected diseases and molecular diagnosis

Of the 20 patients for whom disease was confirmed through molecular diagnosis based on our genetic test, clinically suspected diagnosis and genetic diagnosis were matched in 11 patients (11/20, 55%), including three patients with ADPKD, one patient with ARPKD, two patients with Alport syndrome, three patients with Bartter syndrome, and two patients with Gitelman syndrome. By contrast, the results of our NGS panel reclassified the final diagnosis from initial clinical diagnosis in one patient (5%). This 11‐month‐old boy was initially clinically diagnosed with Bartter syndrome before genetic testing and finally diagnosed with chloride‐secretion diarrhea originating from the intestine and not from the kidneys (Patient 20).

In eight patients, the NGS panel test played an essential role in confirming the genetic cause of their previously undefined kidney disease (8/20, 40%), including one patient with ADPKD with cystic kidney (Patient 5), one patient with Alport syndrome (Patient 12), one patient with hyperoxaluria type 1 (Patient 13), one patient with SLC4A1‐associated renal tubular acidosis (Patient 19) and four patients with CNVs abnormalities (Patients 1, 2, 3 and 4). Detailed results are shown in Figure 1.

FIGURE 1.

FIGURE 1

Correlations between clinical suspicion and results of molecular analysis. ADPKD, autosomal dominant polycystic kidney disease; AS, Alport syndrome; BS, Bartter syndrome; GS, Gitelman syndrome; HUS, hemolytic uremic syndrome; TBMD, thin basement membrane disease; SRNS, steroid resistance nephrotic syndrome [Colour figure can be viewed at wileyonlinelibrary.com]

4. DISCUSSION

In this study, we analyzed the genetic diagnosis of 51 unrelated patients with clinically suspected, inherited kidney disease using a customized NGS panel that included genes related to broad symptoms of kidney disease. Consequently, a total of 39.2% (20/51) of patients were confirmed as having a genetic disease.

Several studies analyzed results using targeted NGS panels to diagnose inherited kidney diseases. Sen et al. reported the results of analysis of an SRNS‐targeted diagnostic gene panel performed for 302 patients, confirming genetic diagnoses in 26.6% of the patients. 23 Another study of 44 patients with typical PKD who underwent targeted NGS testing with 63 related genes revealed 48 related mutation sites in PKD1 and PKD2. 24

It should be noted that in the present study, the NGS panel used did not focus on genes limited to kidney diseases but rather included a broad set of 203 genes related to diseases that might mimic the symptoms of inherited kidney diseases, even though diseases originate from other organs. This approach could facilitate the accurate diagnosis of inherited kidney diseases, as well as the prompt differentiation of genetic diseases with overlapping symptoms, whether these might have originated in the confined kidney or other organs.

One of the advantageous characteristics of this NGS panel was evident based on the notable case of patient 20. This patient visited our hospital for the first time exhibiting lethargy. He had been born at 35.4 weeks of gestation from healthy parents and had two healthy older brothers, with no other notable family history. Fifteen days after birth, he developed abdominal distension suggestive of neonatal necrotizing enterocolitis and received ileostomy surgery. After 2 months, he received another surgery for segmental resection of a 7.9‐cm ischemic ileum lesion and to repair the ileostomy site. On admission, he showed severe hyponatremia and hypokalemic hypochloremic metabolic alkalosis (serum sodium: 128 mmol/L; potassium: 2.5 mmol/L; and chloride: 67 mmol/L; pH 7.652; pCO2: 32.5 mmHg; pO2: 103.0 mmHg; and HCO3: 36.3 mmol/L). Abdominal sonography showed diffuse renal disease with bilateral renal enlargement. Given these results, Bartter syndrome was initially suspected as a diagnosis, and he was referred to our study to precisely identify the genetic etiology of his condition. According to the genetic test, we discovered two homozygous splice‐site pathogenic mutations in SLC26A3 (c.2063‐1G>T), which encodes a transmembrane glycoprotein that exchanges chloride and bicarbonate ions across the cell membrane. His parents were identified as the asymptomatic carriers of c.2063‐1G>T. To confirm the molecular diagnosis, we analyzed the stool of the patient, finding a sodium level of 120 mmol/L. Although there were symptoms that could be mistaken as a disease originating from the kidney, he was finally diagnosed with chloride‐secreting diarrhea, which differed from the first clinical impression. This result of the molecular diagnosis offered the chance of appropriate treatment, focusing salt substitution therapy according to the treatment protocol of chloride‐secreting diarrhea and he has maintained good condition.

Additionally, our findings emphasized the usefulness of CNV analysis. Recent studies report that most CNVs are likely benign, but that some specific variants might be related to genetic diseases, such as neurodevelopmental diseases and various cancers. 25 , 26 , 27 , 28 NGS based CNV detection has a reported sensitivity of up to 92% and specificity of up to 100% for detecting duplications as small as 300 bp and deletions as small as 180 bp in specific genes. 29 , 30 In some inherited kidney diseases, CNVs could also affect susceptibility, and previous studies have highlighted the need for analyzing CNVs in inherited kidney diseases, such as CAKUT. 29 , 31 , 32 In the present study, we detected two known pathogenic CNVs in four patients (Patients 1–4), with both identified as known CNVs that could lead to kidney‐ related symptoms in addition to systemic manifestations. Details of abnormalities in CNVs and patients are described in Table 3.

Regarding the gene variants detected in this study, we found seven novel P/LP variants and two novel exonal deletions among our patient group. Further, there was a noticeable VUS identified in COL4A3, which was found in two unrelated patients. Evidence suggested that this VUS should be reclassified as P/LP, even though it is yet assumed to be a VUS according to ACMG guidelines. Further functional research and segregation analysis of the family of these patients would help define the pathogenicity of this variant.

The present study had a major advantage (ie, using a targeted NGS panel focusing on the phenotype of kidney diseases) that allowed diagnosis of inherited kidney diseases along with differential diagnoses of diseases based on their origin (kidney or other organs), despite their presenting symptoms similar to those of kidney disease. Moreover, we were able to simultaneously obtain relatively high diagnostic performance for CNV analysis with the NGS panel. However, a limitation of the present study is its single‐center research design and inclusion of a small number of patients. Further studies with a larger number of patients might aid verification of these results in the future.

Diagnostic approaches using NGS technology could enable accurate and early detection of genetic diseases and minimize the need for invasive diagnostic procedures, as well as optimize outcomes by broadening therapeutic options. Moreover, presymptomatic testing based on family history could be used to detect the genetic causes of diseases prior to the appearance of overt symptoms, which might allow application of genetic results for prenatal genetic testing and counseling in order to prevent the disease.

This study confirmed the efficacy of NGS with CNV analysis as a diagnostic tool for patients with suspected inherited kidney disease based on their symptoms. The rapid development of NGS technology would enable further clinical applicability of this approach for the diagnosis of inherited kidney disease.

CONFLICT OF INTEREST

The authors declare no potential conflicts of interest.

PEER REVIEW

The peer review history for this article is available at https://publons.com/publon/10.1111/cge.13869.

ACKNOWLEDGEMENTS

The authors express their gratitude to the members of the Clinical Genetics lab at Severance Children's Hospital. The authors received no specific funding for this work.

Oh J, Shin JI, Lee K, Lee CH, Ko Y, Lee J‐S. Clinical application of a phenotype‐based NGS panel for differential diagnosis of inherited kidney disease and beyond. Clinical Genetics. 2021;99:236–249. 10.1111/cge.13869

DATA AVAILABILITY STATEMENT

All relevant data are found within the paper and the Supporting information files.

REFERENCES

  • 1. Stokman MF, Renkema KY, Giles RH, Schaefer F, Knoers NV, van Eerde AM. The expanding phenotypic spectra of kidney diseases: insights from genetic studies. Nat Rev Nephrol. 2016;12(8):472‐483. [DOI] [PubMed] [Google Scholar]
  • 2. Bullich G, Domingo‐Gallego A, Vargas I, et al. A kidney‐disease gene panel allows a comprehensive genetic diagnosis of cystic and glomerular inherited kidney diseases. Kidney Int. 2018;94(2):363‐371. [DOI] [PubMed] [Google Scholar]
  • 3. Cramer MT, Guay‐Woodford LM. Cystic kidney disease: a primer. Adv Chronic Kidney Dis. 2015;22(4):297‐305. [DOI] [PubMed] [Google Scholar]
  • 4. Prakash J, Singh M, Tripathi K, Rai US. Complications of percutaneous renal biopsy. J Indian Med Assoc. 1994;92(12):395‐396. [PubMed] [Google Scholar]
  • 5. González‐Michaca L, Chew‐Wong A, Soltero L, Gamba G, Correa‐Rotter R. Percutaneous kidney biopsy, analysis of 26 years: complication rate and risk factors; comment. Rev Invest Clin. 2000;52(2):125‐131. [PubMed] [Google Scholar]
  • 6. Whittier WL, Korbet SM. Renal biopsy: update. Curr Opin Nephrol Hypertens. 2004;13(6):661‐665. [DOI] [PubMed] [Google Scholar]
  • 7. Rianthavorn P, Kerr SJ, Chiengthong K. Safety of paediatric percutaneous native kidney biopsy and factors predicting bleeding complications. Nephrology (Carlton). 2014;19(3):143‐148. [DOI] [PubMed] [Google Scholar]
  • 8. Renkema KY, Stokman MF, Giles RH, Knoers NV. Next‐generation sequencing for research and diagnostics in kidney disease. Nat Rev Nephrol. 2014;10(8):433‐444. [DOI] [PubMed] [Google Scholar]
  • 9. Mehta L, Jim B. Hereditary renal diseases. Semin Nephrol. 2017;37(4):354‐361. [DOI] [PubMed] [Google Scholar]
  • 10. Devuyst O, Knoers NV, Remuzzi G, Schaefer F. Rare inherited kidney diseases: challenges, opportunities, and perspectives. Lancet. 2014;383(9931):1844‐1859. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 11. Mallett A, Patel C, Salisbury A, Wang Z, Healy H, Hoy W. The prevalence and epidemiology of genetic renal disease amongst adults with chronic kidney disease in Australia. Orphanet J Rare Dis. 2014;9:98. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 12. Hildebrandt F. Genetics of kidney diseases. Semin Nephrol. 2016;36(6):472‐474. [DOI] [PubMed] [Google Scholar]
  • 13. Fallerini C, Dosa L, Tita R, et al. Unbiased next generation sequencing analysis confirms the existence of autosomal dominant Alport syndrome in a relevant fraction of cases. Clin Genet. 2014;86(3):252‐257. [DOI] [PubMed] [Google Scholar]
  • 14. Artuso R, Fallerini C, Dosa L, et al. Advances in Alport syndrome diagnosis using next‐generation sequencing. Eur J Hum Genet. 2012;20(1):50‐57. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 15. Tan AY, Michaeel A, Liu G, et al. Molecular diagnosis of autosomal dominant polycystic kidney disease using next‐generation sequencing. J Mol Diagn. 2014;16(2):216‐228. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16. Siji A, Karthik KN, Pardeshi VC, Hari PS, Vasudevan A. Targeted gene panel for genetic testing of south Indian children with steroid resistant nephrotic syndrome. BMC Med Genet. 2018;19(1):200. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17. Riedhammer KM, Braunisch MC, Günthner R, et al. Exome sequencing and identification of phenocopies in patients with clinically presumed hereditary nephropathies. Am J Kidney Dis. 2020;76:460‐470. [DOI] [PubMed] [Google Scholar]
  • 18. Shang X, Peng Z, Ye Y, et al. Rapid targeted next‐generation sequencing platform for molecular screening and clinical genotyping in subjects with hemoglobinopathies. EBioMedicine. 2017;23:150‐159. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19. Picelli S, Björklund AK, Reinius B, Sagasser S, Winberg G, Sandberg R. Tn5 transposase and tagmentation procedures for massively scaled sequencing projects. Genome Res. 2014;24(12):2033‐2040. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 20. Li H, Durbin R. Fast and accurate long‐read alignment with burrows‐wheeler transform. Bioinformatics. 2010;26(5):589‐595. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 21. Plagnol V, Curtis J, Epstein M, et al. A robust model for read count data in exome sequencing experiments and implications for copy number variant calling. Bioinformatics. 2012;28(21):2747‐2754. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 22. Richards S, Aziz N, Bale S, et al. Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015;17(5):405‐424. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 23. Sen ES, Dean P, Yarram‐Smith L, et al. Clinical genetic testing using a custom‐designed steroid‐resistant nephrotic syndrome gene panel: analysis and recommendations. J Med Genet. 2017;54(12):795‐804. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 24. Wang T, Li Q, Shang S, et al. Identifying gene mutations of Chinese patients with polycystic kidney disease through targeted next‐generation sequencing technology. Mol Genet Genomic Med. 2019;7(6):e720. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 25. Jo HY, Park MH, Woo HM, et al. Application of whole‐exome sequencing for detecting copy number variants in CMT1A/HNPP. Clin Genet. 2016;90(2):177‐181. [DOI] [PubMed] [Google Scholar]
  • 26. Lupski JR. Structural variation in the human genome. N Engl J Med. 2007;356(11):1169‐1171. [DOI] [PubMed] [Google Scholar]
  • 27. Gilissen C, Hehir‐Kwa JY, Thung DT, et al. Genome sequencing identifies major causes of severe intellectual disability. Nature. 2014;511(7509):344‐347. [DOI] [PubMed] [Google Scholar]
  • 28. Beroukhim R, Mermel CH, Porter D, et al. The landscape of somatic copy‐number alteration across human cancers. Nature. 2010;463(7283):899‐905. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 29. Nagano C, Nozu K, Morisada N, et al. Detection of copy number variations by pair analysis using next‐generation sequencing data in inherited kidney diseases. Clin Exp Nephrol. 2018;22(4):881‐888. [DOI] [PubMed] [Google Scholar]
  • 30. Onsongo G, Baughn LB, Bower M, et al. CNV‐RF is a random Forest‐based copy number variation detection method using next‐generation sequencing. J Mol Diagn. 2016;18(6):872‐881. [DOI] [PubMed] [Google Scholar]
  • 31. Westland R, Verbitsky M, Vukojevic K, et al. Copy number variation analysis identifies novel CAKUT candidate genes in children with a solitary functioning kidney. Kidney Int. 2015;88(6):1402‐1410. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32. Sanna‐Cherchi S, Kiryluk K, Burgess KE, et al. Copy‐number disorders are a common cause of congenital kidney malformations. Am J Hum Genet. 2012;91(6):987‐997. [DOI] [PMC free article] [PubMed] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

All relevant data are found within the paper and the Supporting information files.


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