Table 2.

Lyso-Gb1 as specific and sensitive biomarker at diagnosis and clinical presentation

References	Study design	Population	Lyso-Gb1 measurment method	Key findings
Dekker et al. [37]	P, M	64 GD1 34 GD carriers 28 healthy controls	LC/MS/MS	In plasma of all GD1 patients, lyso-Gb1 was increased on average > 200-fold (15.6–1035 nM, median 230.7 nM), while only trace amounts of lyso-Gb1 were present in plasma of control subjects. Plasma lyso-Gb1 levels were not significantly increased in GD carriers. Plasma lyso-Gb1 levels, were significantly correlated with other plasma markers of Gaucher cells at diagnosis, including CCL18 and chitotriosidase, but not with MIP-1β. Lyso-Gb1 values were also associated with disease severity, mainly liver volume and bone mineral density
Rolfs et al. [38]	R, single center	98 GD patients 13 GD carriers 148 healthy controls 262 patients with other lysosomal storage disorders	HPLC–MS/MS	Elevated levels of lyso-Gb1 > 12 ng/ml were identified in GD patients but not in healthy controls, GD carriers, and patients with other lysosomal storage disorders. Lyso-Gb1 was more sensitive and specific than chitotriosidase and CCL18 at diagnosis based on a 12 ng/ml cut-off, which was established with an ideal sensitivity and specificity of 100% in 521 analyzed samples
Murugesan et al. [39]	P	169 GD1 41 healthy controls	LC/MS/MS	Lyso-Gb1 levels were increased by > 200-fold in untreated patients with GD1 compared with healthy controls (180.9 ng/mL versus 1.5 ng/mL). Patients with GD1 and healthy controls were distinguished by a cut off of 4 ng/mL, both with a sensitivity and specificity of 100%. Plasma lyso-Gb1 values between patients with GD1 and healthy controls did not overlap
Chipeaux et al. [40]	P, M	15 GD1 11 healthy controls	UHPLC-MS/MS	Lyso-Gb1 was one to two orders of magnitude higher in both plasma and RBCs of patients with GD1 compared with healthy controls
Tylki-Szymanska et al. [41]	R	64 GD patients	DBS	The variable "disease biomarker level" was dependent of the binary variable "treated with ERT or not" and independent of "disease type", "splenectomized or not", and "heterozygous for 24-bp duplication for CHIT1 variant" or "CHIT1 wild type"
Irùn et al. [42]	R	47 GD patients 19 GD carriers 42 healthy controls 37 patients with other lysosomal lipidoses	LC/MS/MS	Only GD patients displayed lyso-Gb1 levels above 5.4 ng/mL at diagnosis. Plasma lyso-Gb1 was significantly correlated with the biomarkers, chitotriosidase activity and CCL18 (both p < 0.001), but not with clinical parameters related to disease burden
Hurvitz et al. [48]	R	35 mild GD1 34 severe GD1 12 type 3 GD	DBS	Significantly higher lyso-Gb1 levels were identified at baseline in children with more symptomatic disease (i.e., thrombocytopenia, anemia, and hepatosplenomegaly) who subsequently underwent ERT compared with untreated children (p = 0.0003) and, at the last visit, in children with severe GD1 than those with mild GD1 (p = 0.009) In the total patient population, lyso-Gb1 correlated significantly with platelet count (p < 0.0001) and hemoglobin levels (p = 0.003), but not with liver and spleen volume, child’s age, and weight
Saville et al. [49]	R	12 non-neuronopathic GD 11 neuronopathic GD 156 controls 3 GD carriers 37 other-IMD	DBS	Higher median lyso-Gb1 concentrations were detected in DBS from non-neuronopathic GD and neuronopathic GD patients compared with controls (1.65 and 7.07 vs. < 0.06 pmol/spot, respectively). Significantly higher plasma lyso-Gb1 levels were identified in patients with a neuronopathic phentoype than in those with a non-neuronopathic phenotype (p < 0.0001). Elevated plasma lyso-Gb1 levels (70 nmol/L) were detected in a 1-day-old neonate, with an affected older sibling, who was subsequently confirmed as homozygous for N370S. Plasma lyso-Gb1 concentrations of 1,070–2,620 nmol/L were detected in 4 neuronopathic GD patients aged < 20 days old
Stiles et al. [50]	Case report	Case 1: 7-year-old male with GD diagnosed prenatally Case 2: 9-year-old male with GD diagnosed at 5 years of age due to a positive family history	UPLC-MS/MS	Lyso-Gb1, as a key biomarker, is useful in guiding treatment initiation Case 1 had no outward signs of disease such as pain, fracture, or bleeding, however, regular follow-up appointments from 3 years of age identified persistent hepatosplenomegaly and marked elevations in chitotriosidase and lyso-Gb1 levels. ERT was recommended at 7.4 years of age, with marked reduction observed in biomarker values after 3 months of treatment For Case 2, evidence of disease burden (pain, low bone density, and borderline low platelets) alongside elevated chitotriosidase and lyso-Gb1 levels supported the decision to initiation treatment with ERT at 9.2 years of age, with marked reductions in biomarker levels observed after 5 months of treatment
Cozma et al. [51]	R	19 GD patients treated with ERT	DBS	Lyso-Gb1 was reliably detected in DBS samples over a 3-year period. After an involuntary treatment break, the separation of lyso-Gb1 levels “under treatment” versus “not under treatment” was identified with high sensitivity and specificity

CHIT1, Chitotriosidase gene; DBS, dry blood spot; ERT, enzyme replacement therapy; GD, Gaucher disease; GD1, type 1 GD; HPLC–MS/MS, high performance liquid chromatography tandem mass spectrometry; IMD, inherited metabolic disorder; LC/MS/MS, liquid chromatography tandem mass spectrometry; Lyso-Gb1, glucosylsphingosine; M, multicenter; P, prospective; R, Retrospective; RBC, red blood cells; UHPLC-MS/MS, ultra-high pressure liquid chromatography tandem mass spectrometry; UPLC-MS/MS, ultraperformance liquid chromatography-tandem mass spectrometry; vs., versus