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Purpose: Autosomal recessive retinitis pigmentosa (arRP) has recently been associated with mutations in a novel gene, EYS, which is a major gene for this disease. All published mutations so far are based on conventional PCR and are not adequate to identify midsized DNA rearrangements. This study was conducted to establish the prevalence of copy-number variations (CNVs) in the EYS gene in a cohort of arRP patients, including individuals in whom only one pathogenic change was detected by PCR-based sequencing., Methods: A multiple ligation-dependent probe amplification (MLPA) was used for the molecular genetic analyses of CNVs by a novel EYS-specific kit. PCR-based direct sequencing was used in families where a pathogenic deletion or duplication was identified in one allele. Bioinformatics analyses was undertaken to study the effect of the mutations on protein structure and function., Results: Six novel pathogenic CNVs were identified. Also, the presence of four midsized deletions was confirmed in patients previously identified. Midsized genomic rearrangements in EYS are disease causing in ∼4% of the families with no reported mutations and constitute the second pathogenic variation in ∼15% of cases where a mutation has been detected by direct sequencing., Conclusions: This is the first report of a systematic CNV screening of EYS gene in a cohort of arRP patients. Results suggest that midsized genomic rearrangements in EYS gene would be a common event in the appearance of RP phenotype. An efficient and cost-effective strategy validating a novel MLPA kit as a complementary diagnostic method for EYS pathogenic evaluation has been demonstrated.

Purpose: To characterize the molecular defects in two x-linked retinitis pigmentosa (RP) families. We hypothesized that different RPGR mutations result in distinct RP phenotypes., Design: 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.