We report this case to emphasize that appropriate genetic analysis for MODY should be done in young diabetics not coinciding with type 1 or 2 diabetes.
An 18-year-old female patient referred to our clinic with symptoms of dry mouth, polyuria, polydipsia, fatigue, and weight loss (decrease from 58 kg to 51 kg in one month). No chronic diseases or continuous drug usage were noted; her mother had type 2 diabetes. On physical examination, vital signs were stable and systemic examination was normal. In laboratory results, FPG was 261 mg/dL, HbA1C 9.58%, C-peptide 0.9 ng/mL, urine ketone and glucose were positive, blood count and biochemical parameters were normal.
As regards to patient age and clinical findings, pre-diagnosis of type1 diabetes mellitus was established. We started aspart insulin 3x8 unit and detemir insulin 1x12 unit by monitoring blood glucose; then blood glucose stabilized. Anti-GAD and anti-insulin antibodies measured for diagnosis were negative. Due to absence of autoantibodies and positive family history of diabetes, we performed genetic analysis for maturity-onset diabetes of the young (MODY). Compound heterozygous mutation of Ile27Leu/Ser487Asn in hepatocyte nuclear factor 1α (HNF-1α) gene was detected and diagnosis of MODY3 was made.
MODY3 revealed by HNF-1α defect is the most frequently seen MODY type and composes 50-65% of all MODY cases. Many different mutations were defined in HNF-1α gene and clinical findings may differ according to detected mutation. To our knowledge, for the first time in the literature, compound heterozygous mutation of Ile27Leu/Ser487Asn in HNF-1α gene was detected in our case. The mutation possibly had contributed to the aggressive clinical pattern in our patient.