Novel mutations in RPE65 identified in consanguineous Pakistani families with retinal dystrophy

To identify pathogenic mutations responsible for retinal dystrophy in three consanguineous Pakistani families.

A thorough ophthalmic examination including fundus examination and electroretinography was performed, and blood samples were collected from all participating members. Genomic DNA was extracted, and genome-wide linkage and/or exclusion analyses were completed with fluorescently labeled short tandem repeat microsatellite markers. Two-point Lod scores were calculated, and coding exons along with exon-intron boundaries of RPE65 gene were sequenced, bidirectionally.

Ophthalmic examinations of the patients affected in all three families suggested retinal dystrophy with an early, most probably congenital, onset. Genome-wide linkage and/or exclusion analyses localized the critical interval in all three families to chromosome 1p31 harboring RPE65. Bidirectional sequencing of RPE65 identified a splice acceptor site variation in intron 2: c.95-1G>A, a single base substitution in exon 3: c.179T>C, and a single base deletion in exon 5: c.361delT in the three families, respectively. All three variations segregated with the disease phenotype in their respective families and were absent from ethnically matched control chromosomes.

These results strongly suggest that causal mutations in RPE65 are responsible for retinal dystrophy in the affected individuals of these consanguineous Pakistani families.