Clinical Exome Sequencing Identifies NDP Gene Variants in Two Chinese Families with X-Linked Norrie Disease

To explore the genetic defects in two Chinese families with X-linked Norrie disease (ND). We analyzed two Chinese families with ND at molecular level through clinical exome sequencing and the variations were identified by Sanger sequencing. Two genetic variations were found in the NDP gene by clinical exome sequencing, a partial deletion of 801 bp contained the whole exon 2 and a missense variant (164G>A) within codon 55 that resulted in the interchange of cysteine by phenylalanine. Clinical findings were more severe in the patients who presented the missense variant. We report two genetic variations in the NDP gene in Chinese that extend the mutational and phenotypic spectra of NDP gene, and also demonstrate the feasibility of clinical exome sequencing in application of molecular diagnosis.