Maturity-onset diabetes of the young 2 with a novel mutation of glucokinase gene in a Chinese boy and the clinical follow-up

Abstract

To explore the clinical and gene mutation characteristics of a child with maturity-onset diabetes of the young 2 (MODY2). The clinical and follow-up data of 1 patient with MODY2 were reviewed. GCK mutational analysis was performed by PCR and direct sequencing in the proband and his family members. The 9 years and 6 months old boy was referred to our department for short stature and mild hyperglycemia. His fasting blood glucose was elevated to 7.4-7.8 mmol/L, hemoglobin A1C 6.7%. His height was 122 cm (-2 s), weight 25 kg (-1 s), body mass index (BMI) 16.8 kg/m(2). His physical exam was unremarkable without dysmorphic features or acanthosis nigricans. The oral glucose tolerance test (OGTT) showed fasting glucose 8.17 mmol/L, insulin <2.0 mU/L, 2 h glucose 8.69 mmol/L, insulin 5.06 mU /L. The boy was treated with insulin injection for half a year. His fasting blood glucose was stable at 5.6-8.5 mmol/L, hemoglobin A1C 6.7%-6.8%. His mother's fasting blood glucose was 6.86 mmol/L, OGTT 2 h blood glucose 10.36 mmol/L, hemoglobin A1C 6.8%. GCK sequence revealed a novel GCK mutation c.34_44+15del26 in the proband and his mother, which was co-segregated with diabetes. The boy's treatment was shifted from insulin injection to diet and exercise after the diagnosis of MODY2 was confirmed. Being followed up for 2 and a half years, his fasting blood glucose was stable at 4.6-8.0 mmol/L and hemoglobin A1C 6.8%-7.1%. The clinical features of MODY2 are persistent and stable fasting hyperglycemia over a period of months or years and small blood glucose increment (less than 3 mmol/L) after an OGTT (2 h glucose-fasting glucose). We identified a novel c.34_44+15del26 mutation in GCK which co-segregated with diabetes phenotype in this family.