Background: MODY is characterised by an early onset of diabetes and a positive family history of diabetes with an autosomal dominant mode of inheritance. We report a 15 year girl with a HNF1A mutation who presented with MODY without a positive family history.
Objective and hypotheses: HNF1A-MODY is often misdiagnosed as type 1 or type 2 diabetes. Genetic confirmation of MODY in insulin-treated patients helps in making changes in the treatment modality as illustrated below. We tested our patient for HNF1A mutation as she showed features of not being insulin dependant not developing ketoacidosis in the absence of insulin, good glycaemic control on a small dose of insulin and detectable C-peptide measured when on insulin.
Method: A 15 year old presented with fainting episodes and feeling thirsty. Her blood glucose was noted to be 12 mmol/l. She was admitted for further investigation and management.Her blood glucose levels remained between 7 and 12 mmol/l and she had no ketonuria. Her OGTT showed a fasting glucose of 6.7 mmol/l and 14.9 mmol/l at 120 min. Her haemoglobin A1c was elevated at 64 mmol/mol. Her blood glucose levels persistently remained between 8 and 12 mmol/l. She was commenced on MDI with Levemir as basal and Novorapid as bolus at 0.25 units/kg per day. Her ICA and GAD antibodies were negative. Her C peptide was 522 pmol/l reflecting intrinsic insulin secretion. There was no family history of diabetes. She tested positive for heterozygous HNF1 A mutation. Insulin was stopped and she was started on sulphonylureas.
Results and conclusion: The molecular diagnosis of MODY is important to classify the diabetes, predict prognosis and screen asymptomatic family members. Genetic testing of MODY could be considered for carefully selected individuals without a family history of diabetes.
10 - 12 Sep 2016
European Society for Paediatric Endocrinology