Endocrine Abstracts

Introduction: MODY is a group of monogenic disorders contributing to about 1% of diabetes due to a primary defect in the function of the beta cells of the pancreas. Although increasingly recognised, it is often misdiagnosed as type 1 or Type 2 Diabetes Mellitus(T2DM). We describe 7 cases of MODY of which 6 were genetically confirmed.

Case reports: Siblings with loss of function mutation of ABCC8 gen. 2 brothers were diagnosed to have diabetes at 15 and 12 years of age. The first was thought to have T2DM but was investigated based on a normal BMI. A loss of function mutation of ABCC8 gene was identified. The brother had chronic ITP, hyperglycaemia and the same mutation. Siblings with deletion of HNF-1beta gene. Two siblings aged 12 and 16 were identified to have deletion of HNF-1beta gene. The younger sibling was screened based on a strong family history of diabetes. Her renal scan was normal. The brother who was already diagnosed to have diabetes at the time, and had weakly positive islet cell antibodies, was screened based on this report. He also had severe unilateral hydronephrosis. Whole gene deletion of HNF1beta was confirmed. He was not treated with drugs. Parents were found to be gonadal mosaics for HNF1B mutation. Another sibling was a carrier and was referred for annual surveillance. Mutation of HNF-1alphaP291fsinsC gene. This 13-year-old girl had diabetes in both grandparents. Her sister, an adult, was diagnosed to have type 1 Diabetes Mellitus. Splicing mutation of the GCK (Glucokinase) gene. This 15-year-old boy with a strong family history of diabetes has impaired OGTT. Undiagnosed but likely GCK-MODY. This 5-year-old boy with high random blood glucose and impaired Oral Glucose Tolerance Test (OGTT) and negative antibodies is thought to have GCK-MODY though no mutations have been identified.

Conclusion: A high index of suspicion is necessary for diagnosis of MODY, which in turn allows for a different approach to management compared to Type 1 or T2DM. Diagnosis also makes it possible for screening of family members and surveillance of asymptomatic carriers.