Clinical characteristics and genetic analysis of a child with specific type of diabetes mellitus caused by missense mutation of GATA6 gene.

A 2-year-old boy was admitted to our hospital due to polydipsia, polyphagia, polyuria accompanied with increased glucose levels for more than 2 weeks. He presented with symmetrical short stature [height 81 cm (－2.2 SD), weight 9.8 kg (－2.1 SD), BMI 14.94 kg/m (P-P)], and with no special facial and physical features. Laboratory results showed that the glycosylated hemoglobin was 14%, the fasting C-peptide was 0.3 ng/mL, and the islet autoantibodies were all negative. Oral glucose tolerance test showed significant increases in both fasting and postprandial glucose, but partial islet functions remained (post-load C-peptide increased 1.43 times compared to baseline). A heterozygous variant c.1366C>T (p.R456C) was detected in gene, thereby he was diagnosed as specific type of diabetes mellitus. This child had congenital heart disease, and suffered from transient hyperosmolar hyperglycemia state after a patent ductus arteriosus surgery at 11 months of age. Insulin replacement therapy was prescribed, without regularly follow-up thereafter. The latest follow-up was about 3.5 years after diagnosis of diabetes when he was 5 years and 11 months old, with the fasting blood glucose of 6.0-10.0 mmol/L, and the 2 h-postprandial glucose of 17.0-20.0 mmol/L.