Identification of a novel mutation site in maturity-onset diabetes of the young in a Chinese family by whole-exome sequencing

The aim of the present study was to determine the mutant genes and mutation sites in a family with maturity-onset diabetes of the young (MODY), in order to provide evidence for the diagnosis and treatment of clinical MODY. Based on the clinical characteristics of MODY, one family was selected from the Department of Endocrinology of Shanxi Provincial People's Hospital (Shanxi, China). The family comprised seven individuals, four of which were healthy (without MODY), and the whole exome of the individual with MODY, her father and her mother were sequenced. A suspected case (patient's uncle) and a healthy individual (patient's aunt) were sequenced for verification. The Q30 ratio was >90% in the family of three and the sequencing quality was good. The alignment rate was >95%, while the repeat sequence was <10%, with a mean sequencing depth of >120×, which is sufficient to identify mutations. According to Mutation Taster and LRT, it was predicted that the p.leu73Pro mutation of the pancreatic and duodenal homeobox 1 (PDX1) gene was deleterious. The mutation was verified by next-generation sequencing as the pathogenic site in this family. In conclusion, a novel mutation site of MODY type 4 in the PDX1 gene was identified in a family with MODY, which may provide a basis for its clinical treatment. Whole-exome sequencing appears to be of assistance in accurately diagnosing MODY.