A Novel Mutation in the Choroideremia Gene in a Turkish Family.

Choroideremia is an X-linked recessive genetic disorder caused by mutations in the CHM gene. It is a rare retinal dystrophy that manifests as nyctalopia and vision loss, progressing to blindness in later stages. We report a 21-year Turkish man who presented with nyctalopia for the past 4-5 years. His mother and maternal grandmother had similar, but less pronounced complaints. Fundus examination revealed pigmentary changes and retinal atrophy in both eyes. Optical coherence tomography showed outer retinal loss, with central island of preserved autofluorescence surrounded by absent autofluorescence on fundus autofluorescence examination. Goldmann visual fields were constricted. Microperimetry detected retinal sensitivity losses, and full-field electroretinogram demonstrated extinguished cone responses. Genetic analysis revealed a novel nonsense mutation in the CHM gene, namely p.E480X: c.1438G >T. The mutation causes a premature stop codon in exon 12. This is the first report of a G1438T mutation resulting in an E480X premature stop in the CHM gene.