Novel RPGR mutations with distinct retinitis pigmentosa phenotypes in French-Canadian families.
OBJECTIVE
To characterize the molecular defects in two x-linked retinitis pigmentosa (RP) families. We hypothesized that different RPGR mutations result in distinct RP phenotypes.


METHODS
Observational case series.


METHODS
Fifteen members in family I and three members in family II were evaluated. Full ophthalmic evaluations were done. Linkage analyses were performed and likelihood of odds scores (LOD score) were calculated. For mutation analyses, we used dHPLC and automated sequencing.


RESULTS
Two novel RPGR mutations were identified in the two families; a Glu 414 (2-bp del) frameshift mutation in family I and an IVS 2-1 (g to a) splice site mutation in family II. All male family members in family I were severely affected by RP but maintained central visual acuities until their 50s and did not develop a bull's eye maculopathy. The female phenotype was highly variable. Some of the carriers exhibited a severe phenotype, one female displayed an asymmetric phenotype, and other carriers were asymptomatic. All members with the RPGR frameshift mutation exhibited rod-cone electroretinograms abnormalities, whereas five members had hearing loss. Male members of family II were severely affected, with early visual acuity loss, central scotomas, and bull's eye maculopathy. The female family members were asymptomatic but displayed cone-rod electroretinograms changes. There was no hearing loss.


CONCLUSIONS
Different RPGR mutations lead to distinct RP phenotypes, with a highly variable inter- and intrafamilial phenotypic spectrum of disease that is associated with the type of mutation in RPGR and nonrandom X chromosome inactivation, respectively.
D000293:Adolescent; D000328:Adult; D000368:Aged; D002170:Canada; D002352:Carrier Proteins / Q000235:genetics*; D002648:Child; D004252:DNA Mutational Analysis; D004596:Electroretinography; D005136:Eye Proteins; D005260:Female; D016368:Frameshift Mutation; D005602:France; D020868:Gene Silencing; D040181:Genetic Diseases, X-Linked / Q000235:genetics* / Q000473:pathology; D008040:Genetic Linkage; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D010375:Pedigree; D010641:Phenotype; D020419:Photoreceptor Cells, Vertebrate / Q000473:pathology; D022821:RNA Splice Sites / Q000235:genetics*; D012174:Retinitis Pigmentosa / Q000235:genetics* / Q000473:pathology; D014794:Visual Fields
D002352:Carrier Proteins; D005136:Eye Proteins; D022821:RNA Splice Sites; C099929:RPGR protein, human