A novel mutation in the hepatocyte nuclear factor-1β gene in maturity onset diabetes of the young 5 with multiple renal cysts and pancreas hypogenesis: A case report.

A 17-year-old Chinese male was hospitalized exhibiting hyperglycemia and increased serum urea nitrogen and creatinine levels in addition to weight loss. The patient was treated with gliclazide. The patient was 150 cm tall, weighed 35 kg and had no family history of diabetes or kidney disease. Physical examination revealed cephalus quadratus, rachitic rosary and a visible toe-out gait. Laboratory examinations revealed that the patient's fasting plasma glucose and glycosylated hemoglobin levels were markedly increased, fasting plasma C-peptide level was slightly increased and no peak 2 h postprandial was observed. Diabetic autoimmune antibodies [islet cell cytoplasmic autoantibodies (ICA), glutamic acid decarboxylase autoantibodies (GADA), isulinoma-2-associated autoantibodies (IA2A) and insulin autoantibodies (IAA)] were negative. Levels of serum electrolytes decreased, uric acid and parathyroid hormone increased, mild albuminuria was detected and there was a low proportion of urine. The patient also presented with low bone mass and cataracts. Abdominal computed tomography (CT) revealed a bilateral atrophic kidney with multiple renal cysts, primarily located at the junction of renal cortex and medulla, with a diameter of 0.3-0.7 cm. CT also revealed hypogenesis of the body and tail of the pancreas. In an oral glucose tolerance test, the mother and paternal uncle of the patient were diagnosed with type II diabetes and the patient's sister, maternal uncle and paternal grandpa were diagnosed with glucose tolerance impairment. Genetic testing revealed an unreported amino acid mutation in exon 2 of hepatocyte nuclear factor 1β (c.391C>T), a nonsense mutation of CAA to TAA at codon 131. This mutation was identified in the proband but not in any other family members.