A Dominantly Inherited KCNJ11 Q235E Mutation Leading to Diazoxide-Unresponsive Congenital Hyperinsulinism in a Chinese Child

The ATP- sensitive Potassium (K+) channel (K-ATP) controls insulin secretion from the pancreatic islet cells. Genetic mutations causing loss of function in potassium channel subunits are an underlying cause of human congenital hyperinsulinism (CHI). To date, more than twenty KCNJ11 mutations have been revealed, most of which are recessively inherited and refractory to diazoxide treatment. Several dominantly inherited KCNJ11 mutations have been reported recently, all of which are responsive to diazoxide treatment. In this study, we sequenced the KCNJ11 gene in both a Chinese boy diagnosed with congenital hyperinsulinism and in his parents. A dominantly inherited heterozygous missense 703 C > G [p, Q235E] mutation was identified in the patient and in his father. The patient was refractory to diazoxide treatment. This is the first report of a dominantly inherited Q235E KCNJ11 mutation leading to the onset of diazoxide- unresponsive K (ATP) -CHI.