Background/aim: Retinitis pigmentosa (RP) is the commonest form of retinal dystrophy and is usually inherited as a monogenic trait but with remarkable genetic heterogeneity. RP1 is one of the earliest identified disease genes in RP with mutations in this gene known to act both recessively and dominantly although the mutational mechanism remains unclear. This study is part of our ongoing effort to characterise RP in Saudi Arabia at the molecular level.
Methods: Homozygosity mapping and candidate gene analysis.

Background: Calcium binding protein 4 (CABP4),specically located in photoreceptor synaptic terminals, has been associated with congenital stationary night blindness based on this clinical diagnosis being made for three individuals from two Swiss families with CABP4 mutations; however, the few reported cases limit phenotype–genotype correlation. We expand the number
of reported patients with CABP4 mutations and clinically characterise the CABP4-related phenotype.

Retinal dystrophy (RD) is a heterogeneous group of hereditary diseases caused by loss of photoreceptor function and contributes significantly to the etiology of blindness globally but especially in the industrialized world. The extreme locus and allelic heterogeneity of these disorders poses a major diagnostic challenge and often impedes the ability to provide a molecular diagnosis that can inform counseling and gene-specific treatment strategies.