Recessive mutations in the RLBP1 gene encoding cellular retinaldehyde-binding protein in a form of retinitis punctata albescens.

PURPOSE

To determine the frequency and spectrum of mutations in the RLBP1 gene encoding cellular retinaldehyde-binding protein (CRALBP) in patients with hereditary retinal degeneration.

METHODS

The single-strand conformation polymorphism (SSCP) technique and a direct genomic sequencing technique were used to screen the coding exons of this gene (exons 2-8) for mutations in 324 unrelated patients with recessive or isolate retinitis pigmentosa, retinitis punctata albescens, Leber congenital amaurosis, or a related disease. Variant DNA fragments revealed by SSCP analysis were subsequently sequenced. Selected alleles that altered the coding region or intron splice sites were evaluated further through segregation analysis in the families of the index cases.

RESULTS

Four novel mutations were identified in this gene among three unrelated patients with recessively inherited retinitis punctata albescens. Two of the mutations were missense: one was a frameshift, and one affected a canonical splice donor site.

CONCLUSIONS

Recessive mutations in the RLBP1 gene are an uncommon cause of retinal degeneration in humans. The phenotype produced by RLBP1 mutations seems to be a form of retinitis punctata albescens.