The identification of novel mutations within RPGR ORF15 in patients with X–linked cone–rod dystrophy.

Abstract

Abstract: : Purpose:The aim of this study was to identify mutations or polymorphisms in RPGR ORF15 in patients with X–linked cone–rod dystrophy. Methods:X–linked cone–rod dystrophy families were ascertained at Moorfields Eye Hospital. Six unrelated affected males were screened for mutations in RPGR ORF15. A single PCR fragment encompassing the entire 1706bp of ORF15 was amplified using a polymerase with proof reading ability. This fragment was subsequently cloned into pGEMTeasy and plasmid DNA was isolated. The patient DNA insert was sequenced using a combination of M13 vector and ORF15 specific primers to give complete coverage of the 1706bp fragment. Results:Protein truncation mutations were identified in two of the six families. In family1 a G to T transversion was identified at position 1095 (ORF15+1095G>T ) resulting in a nonsense mutation (E365X). In family 2 a G to T transversion at 1176 (ORF15+1176G>T) results in a nonsense mutation (G392X). Conclusions:We have used a cloning strategy to fully sequence ORF15 in male patients and have identified two novel mutations as a cause of X–linked cone–rod dystrophy. Interestingly no mutations were identified in the four other pedigrees, demonstrating that ORF15 mutations may not be the most common cause of X–linked cone–dystrophy.

Keywords: retina • mutations • genetics