['To identify the genetic basis of recessive inheritance of high hyperopia and Leber congenital amaurosis (LCA) in a family of Middle Eastern origin.', 'The patients were examined using standard ophthalmic techniques. DNA samples were obtained and genetic linkage was carried out using polymorphic markers flanking the known genes and loci for LCA. Exons were amplified and sequenced.', 'All four members of this family affected by LCA showed high to extreme hyperopia, with average spherical refractive errors ranging from +5.00 to +10.00. Linkage was obtained to 1q31.3 with a maximal LOD score of 5.20 and a mutation found in exon 9 of the CRB1 gene, causing a G1103R substitution at a highly conserved site in the protein. CRB1 is a vertebrate homolog of the Drosophila crumbs gene, which is required for photoreceptor morphogenesis, and has been associated with either retinitis pigmentosa (RP) or LCA. This sequence variant has previously been reported as a compound heterozygote in one sporadic LCA patient.'] Is a G1103R mutation in CRB1 co-inherited with high hyperopia and Leber congenital amaurosis?