Next-generation sequencing: impact of exome sequencing in characterizing Mendelian disorders.

Traditional approaches for gene mapping from candidate gene studies to positional cloning strategies have been applied for Mendelian disorders. Since 2005, next-generation sequencing (NGS) technologies are improving as rapid, high-throughput and cost-effective approaches to fulfill medical sciences and research demands. Using NGS, the underlying causative genes are directly distinguished via a systematic filtering, in which the identified gene variants are checked for novelty and functionality. During the past 2 years, the role of more than 100 genes has been distinguished in rare Mendelian disorders by means of whole-exome sequencing (WES). Combination of WES with traditional approaches, consistent with linkage analysis, has had the greatest impact on those disorders following autosomal mode of inheritance; in more than 60 identified genes, the causal variants have been transmitted at homozygous or compound heterozygous state. Recent literatures focusing on identified new causal genes in Mendelian disorders using WES are reviewed in the present survey.