Phenotype of an X-linked retinitis pigmentosa family with a novel splice defect in the RPGR gene.

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Abstract

PURPOSE: To assess the clinical phenotype in a Swedish family with X-linked retinitis pigmentosa (XLRP) resulting from a novel splice defect in the RPGR gene. METHODS: RPGR mutation analysis was performed in one family with XLRP, and several individuals from the family were examined clinically. RESULTS: The causative mutation in the family was demonstrated to be a single base-pair change at the splice donor site in intron 7 that resulted in skipping of the complete exon 7 in the mature RPGR transcript. The aberrant mRNA is predicted to produce an RPGR protein with an in-frame deletion of 53 amino acids, corresponding to an RCC1-homology repeat. Clinical studies that included ophthalmological examination and full-field electroretinography showed that this splice mutation resulted in a comparatively less severe form of RP. CONCLUSIONS: Correlation of a causative RPGR genotype with clinical findings in hemizygotes and carrier heterozygotes is an important step toward predictive diagnosis and should assist in the development of gene-based therapies in the future.