Using Next-Generation Sequencing As A Genetic Diagnostic Tool In Some Rare Neurological Mendelian Disorders

BackgroundGenetic diagnosis is the gold standard for investigation of Mendelian disorders. In some Mendelian disorders, a causal mutation may be either present in a number of candidate genes or be characterized by a complex mutational mechanism. Consequently, the unique diagnosis properties of conventional Sanger sequencing make it unsuitable for diagnosing these disorders because of technical restrictions and low throughput. Recently, the use of high-throughput sequence capture methods and NGS technologies has been well established, demonstrating its diagnostic utility in the investigation of heterogeneous diseases.ObjectiveTo evaluate the diagnostic capabilities and values of Next-Generation Sequencing （NGS） and determine the genetic basis of rare neurological Mendelian disorders affecting individuals from8Chinese pedigrees.MethodsAll of the family members from the8Chinese pedigrees were evaluated;8affected individuals were screened by NGS.4probands with ataxia-telangectasia （AT）、1proband with chorea-acanthocytosis （ChAc） and1proband with tuberous sclerosis （TS） were analyzed by targeted gene sequencing （TGS）. Whole exome sequencing （WES） was used to investigate2affected individuals with Nemaline Myopathy （NM） and Limb-girdle muscular dystrophy （LGMD） respectively. All variants were verified by Sanger sequencing or quantitative PCR with the strategy of disease segregation in related pedigrees and the healthy controls.Results14variants was identified for each causative gene; the list included8variants on ATM （c.5697C>A, exon65del; c.477₄81delATCTC, c.4777-2A>T; c.3078G>T, c.7983₇985delTGT; c.331+5G>A, c.1402₁403delAA;）,1variant on VPS13A （c.9403C>T, Hom）,1variant on TSC1（c.3392T>G）,2variants on NEB （c.9052G>A, c.24579G>A）, and2variants on CAPN3（c.2120A>G, c2065₂066delAC）.ConclusionsWe genetically diagnosed8Chinese pedigrees with rare neurological Mendelian disorders with the application of NGS. A diagnostic strategy combining the use of TGS and WES with the aid of well established NGS platforms has been proposed for improving the diagnosis of rare neurological Mendelian disorders.