Endocrine Abstracts

Introduction: Mutations in the variable number of tandem repeats (VNTR) region of the carboxyl-ester lipase (CEL) gene can cause a very rare type of maturity-onset diabetes of the young (MODY 8) characterized by insulinopenic diabetes mellitus (DM) in early adulthood and slowly progressive exocrine pancreatic dysfunction. We present the unusual case of a patient with heterozygosity in a variant of CEL outside the VNTR region suffering from DM, dyslipidemia and exocrine pancreatic dysfunction.

Case-report: A 68-year-old patient was referred to the endocrinology outpatient clinic for evaluation of paroxysmal hypertension. She reported gait and balance disorders, abdominal discomfort and steatorrhea following fatty meals since early adulthood that had significantly deteriorated in the past year. She had a history of gestational diabetes and was eventually diagnosed with DM at the age of 53, treated with metformin. She also had dyslipidemia, Hashimoto’s thyroiditis, osteoporosis, localized scleroderma and a frontotemporal cavernous hemangioma. Clinical evaluation revealed impaired sense of balance and low-normal BMI. Computed Tomography of the abdomen revealed mesenteric lipodystrophy and bilateral adrenal hyperplasia. Biochemical investigation excluded hypersecretion of adrenal hormones. She also had elevated lipid levels and fasting blood glucose (104 mg/dl) with low insulin(1.6 μUI/ml) and low-normal c-peptide levels (1.22 ng/ml). Her HbA1c was 5.7%. Clinical and biochemical findings were suggestive of MODY, therefore genetic testing was performed, which revealed heterozygosity in the CELgene variant c.1341C>A, p.Tyr447Ter. The patient was treated with pancreatic enzymes (pancreatin) with significant improvement of her gastrointestinal and neurological symptoms.

Discussion: CEL is mainly expressed in pancreatic acinar cells and lactating mammary glands. Mutations in the VNTR region of the CEL gene, have been associated with early pancreatic atrophy due to pancreatic fibrosis, lipomatosis or pancreatic cyst formation and progressive exocrine insufficiency as well as adulthood-onset DM. Mutations outside VNTR regions of CEL gene have been associated with dyslipidemias but evidence on insulinopenic DM is scarce. Our patient had a mutation outside of the VNTR region and developed both insulinopenic DM and exocrine pancreatic insufficiency. We hypothesize that our patient’s symptoms were associated with fat-soluble vitamin malabsorption which is corroborated by the significant improvement of her symptoms after dietary modifications and pancretin substitution.

Conclusion: Patients with heterozygous mutations outside the VNTR region of the CEL gene should be investigated for DM and exocrine pancreatic dysfunction and be treated accordingly.