The Gene Mutation Screening Of Three X-linked Recessive Retinitis Pigmentosa Families

ObjectiveTo analyze the linkage status of three Chinese families with X-linked recessive retinitis pigmentosa with the known loci.To find the candidate genes and perform genetic study and mutation screening of these families.Materials and Methods1.Clinic cases were collected and three X-linked recessive retinitis pigmentosa families were identified by family survey,past medical history,ophthalmologic examinations,combined with ERG if necessary.2.Venous blood was collected from research subjects and genomic DNA were extracted.Several STRs ranging from RPGR gene to RP2 gene about 20 cM long were labeled and then amplified by PCR.The haplotype was then identified by SDS-PAGE and argentation.Linkage package was used to calculate LOD scores.3.Twelve pairs of primers designed from hot spot ORF15 of RPGR gene and exon sequences of RP2 gene were used to amplify all these exons.PCR were carried out with human genomic DNA as the template.The PCR products were sequenced after being purified.4.Mutation was identified by comparing DNA sequences of patients with those of normal controls.If there was any change in the family genome, the DNA sequences of all the family members were analyzed and colony screening was performed.ResultsThe genetic pattern of the three families was confirmed as X-linked recessive.There were possibilities that all three families were linked to RPGR and RP2 gene.Mutation c.2336₂337insC was detected on hot spot ORF15 of gene RPGR in family WYS.It was a single insertion which led to frameshift,resulting in structural changes of its coding protein and subsequent onset of retinitis pigmentosa.Mutation c.385 T＞A,c.392 G＞T were detected in the 2^nd exon of gene RP2 in family WXM.They changed the coding amino acids of the spots and induced the onset of retinitis pigmentosa.Mutation c.2233₂234delAG was detected on hot spot ORF15 of gene RPGR in family YYZ.ConclusionNovel mutations of c.2336₂337insC and c.2233₂234delAG on gene RPGR, and novel mutations of c.385 T＞A and c.392 G＞T on gene RP2 were identified,among which the mutation of c.2233₂234delAG on gene RPGR has already been reported.