Novel mutations in genes causing hereditary spastic paraplegia and Charcot-Marie-Tooth neuropathy identified by an optimized protocol for homozygosity mapping based on whole-exome sequencing

Genet Med. 2016 Jun;18(6):600-7. doi: 10.1038/gim.2015.139. Epub 2015 Oct 22.

Abstract

Purpose: Homozygosity mapping is an effective approach for detecting molecular defects in consanguineous families by delineating stretches of genomic DNA that are identical by descent. Constant developments in next-generation sequencing created possibilities to combine whole-exome sequencing (WES) and homozygosity mapping in a single step.

Methods: Basic optimization of homozygosity mapping parameters was performed in a group of families with autosomal-recessive (AR) mutations for which both single-nucleotide polymorphism (SNP) array and WES data were available. We varied the criteria for SNP extraction and PLINK thresholds to estimate their effect on the accuracy of homozygosity mapping based on WES.

Results: Our protocol showed high specificity and sensitivity for homozygosity detection and facilitated the identification of novel mutations in GAN, GBA2, and ZFYVE26 in four families affected by hereditary spastic paraplegia or Charcot-Marie-Tooth disease. Filtering and mapping with optimized parameters was integrated into the HOMWES (homozygosity mapping based on WES analysis) tool in the GenomeComb package for genomic data analysis.

Conclusion: We present recommendations for detection of homozygous regions based on WES data and a bioinformatics tool for their identification, which can be widely applied for studying AR disorders.Genet Med 18 6, 600-607.

MeSH terms

  • Carrier Proteins / genetics*
  • Charcot-Marie-Tooth Disease / diagnosis
  • Charcot-Marie-Tooth Disease / genetics*
  • Charcot-Marie-Tooth Disease / pathology
  • Chromosome Mapping
  • Consanguinity
  • Cytoskeletal Proteins / genetics*
  • Exome Sequencing
  • Female
  • Glucosylceramidase
  • High-Throughput Nucleotide Sequencing / methods
  • Homozygote
  • Humans
  • Male
  • Mutation
  • Pedigree
  • Polymorphism, Single Nucleotide / genetics
  • Spastic Paraplegia, Hereditary / diagnosis
  • Spastic Paraplegia, Hereditary / genetics*
  • Spastic Paraplegia, Hereditary / pathology
  • beta-Glucosidase / genetics*

Substances

  • Carrier Proteins
  • Cytoskeletal Proteins
  • GAN protein, human
  • ZFYVE26 protein, human
  • beta-Glucosidase
  • GBA2 protein, human
  • Glucosylceramidase