Late-Onset Autosomal Dominant Macular Degeneration Caused by Deletion of the CRX Gene

PURPOSE: To characterize the phenotype observed in a case series with macular disease and determine the cause.

DESIGN: Multicenter case series.

PARTICIPANTS: Six families (7 patients) with sporadic or multiplex macular disease with onset at 20 to 78 years, and 1 patient with age-related macular degeneration.

METHODS: Patients underwent ophthalmic examination; exome, genome, or targeted sequencing; and/or polymerase chain reaction (PCR) amplification of the breakpoint, followed by cloning and Sanger sequencing or direct Sanger sequencing.

MAIN OUTCOME MEASURES: Clinical phenotypes, genomic findings, and a hypothesis explaining the mechanism underlying disease in these patients.

RESULTS: All 8 cases carried the same deletion encompassing the genes TPRX1, CRX, and SULT2A1, which was absent from 382 control individuals screened by breakpoint PCR and 13 096 Clinical Genetics patients with a range of other inherited conditions screened by array comparative genomic hybridization. Microsatellite genotypes showed that these 7 families are not closely related, but genotypes immediately adjacent to the deletion breakpoints suggest they may share a distant common ancestor.

CONCLUSIONS: Previous studies had found that carriers for a single defective CRX allele that was predicted to produce no functional CRX protein had a normal ocular phenotype. Here, we show that CRX whole-gene deletion in fact does cause a dominant late-onset macular disease.