Multiple endocrine neoplasia type 1 familial case in a patient with insulinoma and primary hyperparathyroidism: First report in literature and in the Costa Rican population of the c.1224_1225insGTCC pathogenic variant

Abstract

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant disorder without a good genotype–phenotype correlation, characterized by tumor predisposition in the parathyroid gland, anterior pituitary, and pancreatic islet cells. Here, we describe a 37‐year‐old male with previous history of nephrolithiasis, with a 1‐year history of recurrent hypoglycemic episodes. Physical examination revealed the presence of two lipomas. Family history revealed primary hyperparathyroidism (PHPT), hyperprolactinemia, and multiple non‐functioning pancreatic neuroendocrine tumors. Initial laboratories revealed hypoglycemia and primary hyperparathyroidism. A fasting test was positive after 3 hours of initiation. An abdominal CT Scan demonstrated a 28 × 27 mm mass in the pancreatic tail and bilateral nephrolithiasis. A distal pancreatectomy was done. After surgery, the patient persisted with hypoglycemic episodes that were managed with diazoxide and frequent feedings. A parathyroid Tc‐99 m MIBI scan with SPECT/CT imaging demonstrated two hot uptake lesions compatible with abnormally functioning parathyroid tissue. Surgical treatment was offered; however, the patient decided to postpone the procedure. Direct sequence analysis of MEN1 gene revealed heterozygosity for a pathogenic insertion c.1224_1225insGTCC (p.Cys409Valfs*41). DNA sequence analysis was done to six of his first‐degree relatives. A sister with clinical diagnosis of MEN1 and a pre‐symptomatic brother were positive for the same MEN1 variant. To our knowledge, this is the first report of a genetically confirmed case of MEN1 in our country and is the first report in literature of the c.1224_1225insGTCC variant related to a clinically affected family.

This report of a MEN1 family in Costa Rica with a novel MEN1‐pathogenic variant underlines that a thorough analysis may lead to new mutations description, impacts gene biology knowledge, patient follow‐up, and population's genetic characteristics.

1. INTRODUCTION

Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant disorder with inter‐ and intra‐familial variability, without a well‐known genotype–phenotype correlation, characterized by a predisposition for tumors in the parathyroid gland, anterior pituitary, and pancreatic islet cells (de Laat JM, van Leeuwaarde RS and Valk GD, 2018 ¹ , ² , ³ , ⁴ ; Marini, Falchetti, Luzi, & Maria Luisa, 2009 ⁵ ). Non‐classic endocrine and non‐endocrine tumors may also develop such as adrenal cortical tumors, thyroid tumors, lipomas, collagenomas, angiofibromas, meningiomas, and carcinoid tumors (Concolino, Costella, & Capoluongo, 2016 ¹ , ⁴ , ⁵ , ⁶ , ⁷ ). MEN1 syndrome is highly penetrant with half of patients developing signs and symptoms by 20 years of age. ⁶

The gene that causes the disorder, MEN1, was first identified in 1997 and since then more than 613 mutations that affect its coding region have been characterized. ⁸ However, up to 10%–20% of MEN1 patients will not have mutations in the coding region or adjacent splice sites of MEN1. ¹ , ² , ⁸ Other genes such as AIP, CDKN1B, CDKN2B, CDKN2C, and CDKN1A have been related to MEN1. ⁹

The diagnosis of MEN1 is defined as the simultaneous presence of at least two of the three characteristic tumors (pituitary, parathyroid, or pancreatic islets); the occurrence of at least one of the MEN1‐associated tumor and a first‐degree relative with MEN1; or, if a known MEN1 mutation is present, irrespective of clinical or biochemical manifestation. ⁵ , ⁷ , ¹⁰ Here, we report the first genetically confirmed Costa Rican familial MEN1 case in a 37‐year‐old male with primary hyperparathyroidism (PHPT), insulinomas, and family history of PHPT, hyperprolactinemia, and non‐functioning pancreatic neuroendocrine tumors.

2. CASE REPORT

In November 2017, a 37‐year‐old male with medical history of recurrent nephrolithiasis was referred to the endocrinology department at San Juan de Dios Hospital, C.C.S.S., in San José, Costa Rica. The patient had a 1‐year history of recurrent episodes of diaphoresis and distal tremor in fasting states that resolved with eating. Over time these episodes became more frequent and symptomatic associating difficulty in waking up, depressive symptoms, and paresthesia in all his extremities.

Family medical history revealed PHPT, prolactinoma and multiple non‐functioning pancreatic neuroendocrine tumors in a sister; PHPT and hyperprolactinemia in one of her daughters; and PHPT in her oldest daughter. His mother and son were asymptomatic. His father died 36 years ago of an uncertain history of liver cirrhosis, at 50 years of age.

Physical examination exhibited a male with a body mass index of 31.4 Kg/m². He had symmetrical neck without palpable masses or adenopathies. His abdomen was soft and non‐tender and there were no palpable masses. In the dorsal region, the patient presented two lipomas of approximately 2 × 2 cm and 1 × 1 cm. Neurologic examination was normal.

Initial laboratories revealed a fasting serum glucose of 38 mg/dL, serum calcium level of 11.3 mg/dL, and a serum intact parathyroid hormone level of 69.5 pg/mL (normal range, 11–67 pg/mL) consistent with hypoglycemia and PHPT. All serum pituitary hormone levels were within the normal range. Gastrin measurement was not available. A fasting test was done. At 3 h, we documented a serum glucose of 47 mg/dL, serum insulin of 243 pmol/L (normal range, 43.3–170.4 pmol/L), and serum C‐peptide of 6.58 ng/mL (normal range, 0.90–7.10 ng/mL) compatible with insulinoma. Medical treatment with diazoxide and frequent feedings was initiated.

An abdominal CT scan showed one slightly hyperdense solid focal lesion of 28 × 27 mm localized in the pancreatic tail and bilateral nephrolithiasis (Figure 1).

FIGURE 1.

CT scan of abdomen. (A) Red arrowhead shows solid lesion located in pancreatic tail. (B) Red arrow shows left nephrolithiasis.

A distal pancreatectomy was done. The microscopic study of the specimens showed multiple microscopic nodules. Some of them revealed positivity for insulin and some for glucagon. Immunohistochemical studies, revealed positivity for cytokeratin 8–18, synaptophysin, chromogranin, E‐cadherin, and a Ki‐67 proliferation index <2%. Beta‐catenin was negative in the nuclei and positive in membranes and cytokeratin 7 was negative (Figure 2). This finding was consistent with multifocal neuroendocrine tumors.

FIGURE 2.

Histological photomicrograph of the pancreatic specimen demonstrating the presence of a neuroendocrine tumor. (A): Groups of cells with oval nuclei with chromatin in “salt and pepper” pattern (Hematoxylin and Eosin, 400×). B, C, D and E: Immunohistochemical studies (400×). (B): Cytokeratin 8/18. (C): Synaptophysin. (D): Chromogranin. (E): ki‐67 (<2%). Servicio de Patología, Hospital San Juan de Dios, Costa Rica.

Approximately 36 h after the surgery, the patient presented an episode of hypoglycemia of 39 mg/dL. For this reason, medical treatment with frequent feedings and diazoxide was continued. Once he was stabilized, the patient was discharged with medical treatment. However, a subsequent hospitalization was required for persistent hypoglycemic symptoms. During the two‐month follow‐up, two CT scans and an endoscopic US (EUS) were done. Since no residual neuroendocrine tumor could be demonstrated it was decided, in conjunction with the patient, to continue with medical management and not perform surgical reintervention due to the high morbidity and mortality it represented.

Since initial laboratories revealed primary hyperparathyroidism, a parathyroid Tc‐99 m MIBI scan with SPECT/CT imaging was done. The study demonstrated two hot uptake lesions at the inferior pole of the left and right thyroid gland of 10 × 10 × 13mm and 12 × 7 × 13mm, respectively, compatible with abnormally functioning parathyroid tissue. Surgical treatment was offered; however, the patient decided to postpone the procedure.

As part of a patient initiative, genomic DNA sequence analysis and deletion/duplication testing from peripheral blood leukocytes was done in a clinical commercial laboratory. Direct sequence analysis of MEN1 compared with the published cDNA reference sequence (GenBank accession number NM_137099.2) revealed heterozygosity for a 4‐bp insertion:

c.1224_1225insGTCC (p.Cys409Valfs*41).

Molecular analysis of the variant showed that while this is not anticipated to result in nonsense‐mediated mRNA decay, it is expected to disrupt the last 202 amino acids of the MEN1 protein which would likely result in truncation of the protein and its functionally conserved nuclear localization signal (NLS) domains (Figure 3). However, the consequences of this mutation on the protein are hypothetical, since no molecular characterization of menin in normal or tumor tissue from our patient was done. This variant is not present in population databases (genomAD) and has not been reported in the literature in individuals with MEN1‐related disease. ClinVar contains an entry for this variant (Variation ID: 428066) related to hereditary cancer‐predisposing syndromes but no further details are given. Literature analysis showed that several different variants located downstream of this variant have been determined to be pathogenic (p.Arg516fs, p.Phe447Leufs*10, p.Arg452Phefs*74, p.Phe514Thrfs*44). ⁴ , ⁸ This suggests that deletion of this region of the MEN1 protein is causative of the disease. Experimental studies have shown that disruption of this region abrogates the ability of MEN1 to bind DNA, regulate target gene expression, and inhibit cell proliferation. ¹¹ , ¹² For these reasons, this variant has been classified as pathogenic according to the ACMG guidelines.

FIGURE 3.

(A) Schematic representation of MEN1 gene. Rectangles represents MEN1 exons numbered from 1 to 10. Non‐coding regions are dark. Coding areas are white. The MEN1 variant c.1224_1225insGTCC is located in exon 9. The variation is numbered in relation to the MEN1 cDNA reference sequence (GenBank accession number NM_130799.2). Modified from. ⁸ (B) Schematic representation of menin with the resulting p.Cys409Valfs*41 variation. The white rectangle represents the amino acids of menin that are translated. The dark rectangle represents the amino acids that are untranslated. The stop signal expected at position 450 could result in truncation of the protein including the NLS1, NLSa, and NLS2 domains. Variation is referred to NP_570711.1. Modified from. ⁶ NLS, Nuclear localization signal.

Further DNA sequence analysis was done to six of his twelve first‐degree relatives (Figure 4). The sister with clinical diagnosis of MEN1 (II7) and an asymptomatic brother (II3) were positive for the same MEN1 variation. His brother, who was clinically asymptomatic at the moment of investigation, revealed mild hyperprolactinemia on biochemical studies. The rest of the first‐degree relatives were clinically asymptomatic at the moment of the evaluation without systemic manifestations of related hypercalcemia such as: altered mental status (lethargy, depression, decreased alertness, confusion), anorexia, constipation, nausea, vomiting, dehydration, hypercalciuria, increased risk for kidney stones, increased bone resorption, increased fracture risk, or exacerbation of hypertension. All the confirmed patients and the not genetically tested will enter a periodic clinical and biochemical surveillance program to complete the clinical follow‐up and to identify early signs not depicted in the initial evaluation. The details of mutation status, diagnosis, and treatment of the affected family members are described in Table 1.

FIGURE 4.

Pedigree of the family carrying MEN1 c.1224_1225insGTCC variant. Generations are indicated by Roman numerals I, II, and III. Black symbol, affected subject; square, male; circle, female; diagonal line, deceased individual; arrow, proband; plus sign, MEN1 variant carrier; minus sign, negative for the MEN1 variant; asterisk, proband's first‐degree relatives that were not genetically tested. Age and cause of death is indicated below the symbols. Only the first‐degree relatives of the individuals that have been confirmed to be carriers for the variant are represented.

TABLE 1.

Variation status, diagnosis, and treatment of the members with diagnosis of MEN1 in the family carrying MEN1 c.1224_1225insGTCC variant.

Subject	DOB a	Variation status	Diagnosis	Treatment
II1 (Proband)	11/17/79	+	PHPT a Insulinoma	Differed surgical treatment 2018 Distal pancreatectomy 2018 Diazoxide and frequent feedings Follow‐up
II3	11/8/75	+	Hyperprolactinemia	Follow‐up
II7	4/9/69	+	Prolactinoma Non‐functioning neuroendocrine pancreatic tumors PHPT	2002 Dopamine agonist therapy 2012 Distal pancreatectomy 2013 Total parathyroidectomy Follow‐up b
III6	9/18/87	NA a	Hyperprolactinemia PHPT	2013, Dopamine agonist therapy 2016 Subtotal parathyroidectomy Follow‐up
III7	1/14/86	NA	PHPT	2014 Subtotal parathyroidectomy Follow‐up b

^a DOB: date of birth; NA: not available; PHPT: primary hyperparathyroidism.

^b Patients with follow‐up in a different medical center.

3. DISCUSSION

The estimated prevalence of MEN 1 is between 1 and 10 per 100,000. ³ MEN 1 syndrome was first described in 1903 by Erdheim in a report of an autopsy of a patient with acromegaly and enlarged parathyroid glands. ⁶ In 1988, the MEN1 locus was mapped to chromosome 11q13, and by 1997 MEN1 mutations were confirmed to cause MEN1 ( ⁸ , ¹³ ; Jensen, Berna, Bingham, & Norton, 2008 ⁴ , ⁶ ;). To our knowledge, this is the first confirmed case of a Costa Rican family with a pathogenic MEN1 variant.

MEN1 is located on chromosome 11q13 and consists of 10 exons which contain a coding region of 1.83 kb organized into nine exons that encode a 610‐amino acid protein called menin ( ¹ , ³ , ⁴ , ⁶ , ⁸ , ¹⁴ ; Norton, Krampitz, & Jensen, 2015 ⁵ , ⁷ ;). Menin is an ubiquitous protein that has at least three nuclear localization signals (NLS1, NLSa, and NLS2) at its C terminus, at amino acids 479–497, 546–572, and 588–608, respectively. ¹ , ² , ⁴ , ⁶ , ⁷ , ⁸ , ¹⁴ These regions, rich in positively charged residues, have been reported to directly bind to double‐stranded DNA which is thought to be necessary to target menin into the nucleus. ² , ⁴ , ⁷ , ⁸ Menin interacts with several proteins involved in DNA transcriptional regulation, genome stability, cell division, cell proliferation, and epigenetic regulation. ⁴ , ⁷ , ⁸ , ¹⁴ , ¹⁵

MEN1 mutations can be identified in 70%–95% of MEN1 patients. ⁴ , ⁶ From 1997 to 2015, 576 MEN1‐related mutations have been reported. ⁸ Most mutations occur in exons 2, 9, and 10 where deletional or insertional hot spots may be associated with DNA sequence repeats. ⁸ Of these mutations, 42% are frameshift insertions or deletions, 25.5% are missense mutations, 14% are nonsense mutations, 5.5% are in‐frame insertions or deletions, 10.5% are splice site mutations, and 2.5% are large deletions. ⁸ Most frameshift and nonsense mutations are predicted to result in a truncated protein with the consequent loss of functional domains, including the NLSs located in the C‐terminal segment, or in loss of the translated protein because of nonsense‐mediated mRNA decay (NMD). ⁴ , ⁸ Our MEN1 variant is located in exon 9, and it is expected to cause a premature translational stop signal downstream to the 450‐codon level and to disrupts the last 202 amino acids which could hypothetically result in truncation of the functionally conserved NLS domains of MEN1.

MEN1 follows Knudson's “two‐hit” model for tumor suppressor gene carcinogenesis. ² , ⁵ , ⁶ Inheritance of a germline MEN1 mutation (familial cases) or a MEN1 mutation developed in an early embryonic stage (sporadic cases) predisposes an individual to develop tumors. ⁶ If a somatic mutation occurs in wild‐type allele, cells acquire the survival advantage needed for tumor development. ⁶ However, in almost 10% of MEN1‐associated tumors, this is not observed and it is usually due to inactivation of the wild‐type allele as a result of a point mutation or a small deletion or insertion within the coding region or splice sites of the MEN1, mechanisms still consistent with the Knudson two‐hit hypothesis. ² , ⁵ , ⁶

Skin and subcutaneous tumors may arise in 90% of MEN1 patients. ³ Approximately 88% of MEN1 patients present angiofibromas, 72% collagenomas, and 34% lipomas. ¹⁵ The presence of cutaneous tumors may be helpful in the clinical presymptomatic diagnosis of MEN1 patients, as often they appear before any clinical manifestations of MEN1‐associated hormone‐secreting tumors. ⁶ Our patient had two palpable lipomas.

PHPT affects 95% of MEN1 patients and presents as the first endocrine manifestation in 90%–100% of MEN1 cases. ⁶ , ⁷ , ⁸ , ¹⁵ Typical presentation is between 20 and 25 years of age with 100% of penetrance by the age of 50. ² , ⁶ , ⁷ , ¹⁵ In our case, four of the family members with the diagnosis of MEN1 presented PHPT and two of them presented PHPT as their first manifestation.

MEN1 patients with PHPT are prone for severe morbidity due to bone mineral loss and urolithiasis. ¹⁰ Surgical removal of the abnormally overactive parathyroid glands is the definitive treatment for symptomatic patients. ⁵ Asymptomatic patients should have regular assessment for symptom onset and complications. ⁵ Preoperative imaging, such as Tc99m‐sestamibi parathyroid scintigraphy, is of limited benefit because all parathyroid glands may be affected in MEN1 patients. ⁵ Surgical treatment was offered to the patient; however, he decided to postpone the procedure. Once the diagnosis MEN1 is confirmed the surgical approach differs from sporadic adenomas and there is still discussion on how aggressive the surgical approach should be. ⁵

Multiple endocrine neoplasia type 1 (MEN1) is characterized by the combined occurrence of tumors involving the parathyroid glands, pancreatic islets, and anterior pituitary gland. Pancreatic islet cell tumors, also referred to as pancreatic neuroendocrine tumors (P‐NETs), may secrete gastrointestinal (GI) hormones (e.g., gastrin, insulin, glucagon) and result in clinical syndromes of hormone excess, or they may not secrete hormones and are referred to as non‐secreting or non‐functioning (NF) P‐NETs. In addition, such P‐NETs may secrete pancreatic polypeptide (PP), which does not lead to clinical manifestations of hormone excess and PPomas are therefore often classified as NF P‐NETs. ¹⁶

Insulinomas arise in about 10%–30% of MEN1 patients and are the second most frequent functioning pancreatic islet tumor after gastrinomas. ⁵ , ⁶ , ¹⁵ Insulinomas usually occur in the third decade of life. ⁵ , ⁶ , ¹⁴ , ¹⁵ The most reliable test for the diagnosis is a supervised 72 h fast, during which an increased concentration of plasma insulin in association with hypoglycemia is demonstrated, along with an elevated C‐peptide and proinsulin concentrations. ⁵ , ⁶ , ¹⁵ In our case, the diagnosis was made with a fasting test positive at 3 h when the patient was 37 years old.

Insulinomas usually present as multiple lesions which are generally small (<2 cm), benign, and distributed uniformly throughout the whole pancreas. ⁶ , ¹⁵ The multiplicity makes it difficult to define which tumor is secreting the excessive insulin; nonetheless, the majority of MEN1 patients typically have a dominant insulinoma predominantly found in the body or tail of the pancreas. ¹⁵ In our case, the patient's recurrence of hypoglycemic episodes after surgery and the multiplicity of the nodules in histological studies suggests the presence of residual lesions in the remaining pancreas.

Insulinomas in MEN1 patients are almost invariably treated surgically. ⁵ , ⁶ , ¹⁴ , ¹⁵ Diazoxide combined with frequent feedings can also be used to control the hypoglycemia. ¹⁴ , ¹⁵ However, like in our case, approximately 40%–50% of the patients do not respond adequately to this treatment. ¹⁴ Long‐acting somatostatin analogues, such as octreotide or lanreotide, are an alternative treatment. ¹⁴ Nevertheless, they are effective in only 40%–50% of patients. ¹⁴

Anterior pituitary tumors occur in 15%–90% of MEN1 patients. ⁵ , ⁶ Approximately 60% secrete prolactin, fewer than 25% secrete GH, 5% secrete ACTH, and the remainder appear to be non‐functioning. ⁶ Pituitary tumors present as the first clinical manifestation of MEN1 syndrome in 10% of familial cases. ² , ⁵ , ⁶ Our patient's serum pituitary hormones were within the normal range. A sister (II3) and her daughter (III6) presented symptomatic hyperprolactinemia as their first clinical manifestation.

MEN1 is known for causing significant morbidity and a reduction in life expectancy. ⁵ , ¹⁰ Therefore, a timely and accurate diagnosis of MEN1 is paramount to improve disease outcomes. ⁵ , ¹⁰ Genetic mutation analysis should be offered to all patients meeting the familial or clinical criteria for diagnosis of MEN1, and patients presenting with a MEN1‐related tumor. ⁵ , ¹⁰ With genetic testing, it was possible to identify the variant in an asymptomatic brother (II3). This allows an early identification of tumor manifestations and timely treatment for reducing morbidity and improving survival. ¹ , ² , ⁵ , ⁶ , ¹⁰ Furthermore, the relatives that do not carry the variant can avoid exposure to radiation from imaging, unnecessary healthcare costs and anxiety of developing an associated MEN1 tumor. ⁵ , ¹⁰ Nonetheless, in our context, routine genetic diagnosis can be difficult since we did not have our own DNA sequencing laboratory clinically validated at the time of the study.

The clinical practice guidelines recommend screening since early childhood. ⁵ , ¹⁰ In our country biochemical screening for the different presentations of neuroendocrine tumors (NET) is possible as well as CT, endoscopic ultrasound or MRI scans as suggested. Pediatric manifestations of MEN1 are rare. ¹⁰ The potential benefits against potential harm from radiation by imaging studies, quality of life, and costs should be weighed by the physician. ¹⁰ Gallium68 Dotatatoc PET scan that has a high sensitivity and specificity for detection of NET ¹⁷ is only available in private medicine and not easily accessible for routine follow‐up. Since no apparent genotype–phenotype relation has been described for MEN1, it is difficult to make an individualization of the MEN1 follow‐up. ⁵ , ¹⁰ One of the challenges of our public healthcare system is the laboratory and imaging resources access. Therefore, in our case, first‐degree relatives who are at risk will undergo a periodic clinical and biochemical follow‐up with total serum calcium, serum prolactin, fasting serum glucose, insulin concentration, and IGF‐1 concentration, imaging frequency will be defined by clinical and biochemical findings.

To our knowledge, this is the first report of a genetically confirmed case of MEN1 in our country and is the first report in literature of the c.1224_1225insGTCC variant related to a clinically affected family.

AUTHOR CONTRIBUTIONS

Paula Molina: Writing – original draft; writing – review and editing. Ernesto Ruiz: Writing – original draft; writing – review and editing. Oscar Badilla‐Barboza: Supervision; writing – original draft; writing – review and editing. Giovanni Sedó: Supervision; writing – original draft; writing – review and editing. Laura Barboza‐Rodriguez: Investigation; writing – original draft; writing – review and editing. Ramses Badilla Porras: Investigation; supervision; writing – original draft; writing – review and editing.

CONFLICT OF INTEREST STATEMENT

The authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria, educational grants, participation in speakers' bureaus, membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent‐licensing arrangements), or non‐financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.

FUNDING STATEMENT

None.

CONSENT

Written informed consent was obtained from the patient to publish this report in accordance with the journal's patient consent policy.

Molina‐Céspedes P, Ruiz‐Golcher EJ, Badilla‐Barboza O, Sedó‐Mejía G, Barboza‐Rodríguez L, Badilla‐Porras R. Multiple endocrine neoplasia type 1 familial case in a patient with insulinoma and primary hyperparathyroidism: First report in literature and in the Costa Rican population of the c.1224_1225insGTCC pathogenic variant. Clin Case Rep. 2023;11:e7041. doi: 10.1002/ccr3.7041

DATA AVAILABILITY STATEMENT

Datasets analyzed during the current study are available in the data repository at the National Children's Hospital—Department of medical Genetics. Results of specific studies are available in the National Electronic Medical Record System (EDUS).