Genes and hearing loss

Many cases of unexplained deafness have a genetic origin, even when there is no family history. Until recently, genetic testing has been unrewarding, as so few come up with a positive result. Shearer et al (J Med Genet 2013;50:627–34) from Iowa describe their work using recently developed genetic techniques to improve the yield greatly. They recruited 100 patients with non-syndromic hearing loss that clearly did not have an environmental cause, irrespective of family history or previous investigation. Their DNA was then examined using targeted genomic enrichment (TGE) and massive parallel sequencing (MPS) techniques, and the findings analysed using sophisticated bioinformatics. A large and heterogeneous panel of variants were identified that appeared to be associated with hearing loss. They found a positive genetic diagnosis in 46% overall, with higher detection rates in those with symmetric hearing loss and with an autosomal recessive inheritance pattern. ‘Next generation’ sequencing technology (which is the same as MPS) is becoming increasingly available. Sequencing whole exomes or …