Novel myosin mutations for hereditary hearing loss revealed by targeted genomic capture and massively parallel sequencing

Abstract

Hereditary hearing loss is genetically heterogeneous, with a large number of genes and mutations contributing to this sensory, often monogenic, disease. This number, as well as large size, precludes comprehensive genetic diagnosis of all known deafness genes. A combination of targeted genomic capture and massively parallel sequencing (MPS), also referred to as next-generation sequencing, was applied to determine the deafness-causing genes in hearing-impaired individuals from Israeli Jewish and Palestinian Arab families. Among the mutations detected, we identified nine novel mutations in the genes encoding myosin VI, myosin VIIA and myosin XVA, doubling the number of myosin mutations in the Middle East. Myosin VI mutations were identified in this population for the first time. Modeling of the mutations provided predicted mechanisms for the damage they inflict in the molecular motors, leading to impaired function and thus deafness. The myosin mutations span all regions of these molecular motors, leading to a wide range of hearing phenotypes, reinforcing the key role of this family of proteins in auditory function. This study demonstrates that multiple mutations responsible for hearing loss can be identified in a relatively straightforward manner by targeted-gene MPS technology and concludes that this is the optimal genetic diagnostic approach for identification of mutations responsible for hearing loss.

Myosin VI Must Dimerize and Deploy Its Unusual Lever Arm in Order to Perform Its Cellular Roles

“…However, it provided no rescue of either endocytosis or Golgi morphology in myosin VI null ( sv/sv ) fibroblasts (Figure 5). These results likely explain why a myosin VI mutation within this internal dimerization region, L926Q (Figure 1A), causes congenital deafness in humans (Brownstein et al, 2014). …”

“…In a second mutant construct, MVI FL -SAH mimic , residues from Glu922 to Arg940 (underlined in sequence) were replaced with alternate acidic and basic residues (shown in light green bar under sequence) to create a consensus SAH. The red asterisk denotes the position of leucine 926, which when mutated to a glutamine, causes congenital deafness in humans (Brownstein et al, 2014). B.…”

The GPSM2/LGN GoLoco motifs are essential for hearing

“…The pattern of hearing loss suggests an autosomal recessive mode of inheritance. Following screening for GJB2 and other common deafness genes in the Palestinian population (Shahin et al 2010), DNA from individual III-7 underwent TGE on a panel of 284 hearing loss-associated genes and subsequent MPS (Brownstein et al 2014). Indel and copy number variants (CNV) were excluded, and the only homozygous candidate recovered in the single nucleotide variant (SNV) analysis was c.977G >A in the GPSM2 gene (NM_013296.4) at chr1:109445771.…”

“…Members of Family α33 were ascertained with informed consent, as part of a larger study to identify genes involved in deafness in the Palestinian Arab deaf population (Brownstein et al 2014). A medical history was collected regarding the deaf proband and other affected individuals, including type and degree of hearing loss, age at onset, evolution and symmetry of the hearing impairment, use of hearing aids, the presence of tinnitus, medication, noise exposure, pathologic changes in the ear, and other relevant clinical manifestations, including vision problems, motor development, intellectual disability, and family history and consanguinity.…”

“…Library preparation, massively parallel sequencing, and bioinformatic analysis were performed as previously described (Brownstein et al 2011, 2014). Sanger sequencing was performed on a 3130 Genetic Analyzer (Applied Biosystems).…”