Next generation sequencing technology for detecting a new RET gene mutation in two Hirschsprung’s disease families

Objective To identify the disease-causing gene mutation in two families of Hirschsprung’s disease (HSCR). Methods Two HSCR families from Liaoning Province were collected to analyze genomic DNA. Whole-exome genome mutation screening and copy number variation (CNV) analysis were performed on whole-genome DNA extracted from blood using next-generation sequencing (NGS) technology. Combining the hazard and pathogenicity analysis of mutation and clinical phenotype of family members screening susceptible pathogenic gene for sequencing results. Then classical Sanger’s method was applied for verifying the obtained results. Results Among 4 persons in family 1, both children were affected, the mother had similar clinical manifestations but the diagnosis was absent, the father had no phenotype. After filtering out common mutations and synonymous mutations, 633 SNPs and 35 InDel mutations were detected by whole-exome sequencing. The sequencing results revealed heterozygous mutation c. 2599G>T in exon 14 encoding region of RET gene and it was confirmed as a pathogenicity mutation through the hazard and pathogenicity analysis of mutated protein. Among 4 persons in family 2, both offsprings were identified as HSCR, but one of them dying in neonatal period failed to obtain a peripheral blood sample. Sequencing results revealed 609 SNPs and 30 InDel mutations. Comprehensive analysis of mutations, genetic patterns, clinical features and other factors failed to detect a distinct pathogenic mutation in this family. Conclusions NGS can screen out new HSCR-related gene mutations and provide etiological insights of HSCR. Key words: Hirschsprung disease; DNA sequencing; Etiology