Somatic and gonadal mosaicism in X-linked retinitis pigmentosa†

The g.ORF15 + 652–653delAG mutation in the RPGR gene is the most frequent mutation in X-linked retinitis pigmentosa (XLRP). The objective of this study was to investigate the possibility of mosaicism in an XLRP family. Eight subjects in the RP family were recruited. Blood samples were collected for DNA extraction. Haplotype analysis and mutational screening on the RPGR gene were performed. Additionally, samples of hair follicles and buccal cells from the mother of the proband were acquired for DNA extraction and molecular analysis. Phenotype was characterized with routine ophthalmic examination, Goldmann perimetry, electroretinography, and color fundus photography. A g.ORF15 + 652–653delAG mutation was identified in second- and third-generation patients/carriers. A first-generation female, who was considered to be an obligate carrier, demonstrated a normal phenotype as well as a normal genotype in lymphocytic DNA, indicating the gonadal mosaicism; however, a heterozygous AG-deletion at nucleotide 652 and 653 was identified in the genomic DNA of hair follicles, hair shaft, and buccal cells, indicating that the mutation is somatic. In conclusion, we reported on a family in which an asymptomatic woman with somatic–gonadal mosaicism for a RPGR gene mutation transmitted the mutation to an asymptomatic daughter and to a son with XLRP. Gonadal mosaicism may be responsible for a proportion of multiplex or simplex RP families, in which more than 50% of all cases of RP are found. © 2007 Wiley-Liss, Inc.