Genetic testing in retinal dystrophies

Purpose To describe genetic testing in autosomal recessively inherited retinal dystrophies. Methods Retinal dystrophies (RD) are a heterogeneous group of diseases characterised by progressive retinal degeneration leading to severe visual disability. The prevalence of RD is ~ 1/3500; of these up to 40% are presumed autosomal recessive (AR). AR inheritance is frequently seen in juvenile onset cases, but also presents in young adults. The heterogeneity of inherited eye disease can make differential diagnosis difficult. For a sporadic case in a young male the differential diagnosis may include autosomal recessive, X‐linked or autosomal dominant RD. Although there are no treatments yet available for inherited RD, knowledge of the underlying genetic variation can be helpful for: clinical diagnosis in patients with signs and symptoms of disease; pre‐symptomatic testing for individuals who do not have the disease, but given their family history, are at risk for the disease; carrier testing for individuals who may carry a gene mutation that can be passed on to their children; and may be useful if genetic therapy becomes a viable option. Methods: Testing strategies using novel technologies are now being adopted to increase identification of disease causing mutations. One major advance includes the use of high throughput sequencing platforms. The introduction of this technology is likely to overcome many of the problems associated with testing multiple patient samples and multiple genes, as well as providing the accuracy required in a diagnostic setting. Even these technologies will not identify all types of mutations, for example large deletions so other technologies will be required.