SCREENING FOR MUTATIONS IN A NOVEL RETINA-SPECIFIC GENE AMONG CHINESE PATIENTS WITH RETINITIS PIGMENTOSA

To identify and evaluate mutations in the RPl gene among Chinese patients with retinitis pigmen-tosa (RP).Methods. Leukocyte DNA of 92 RP patients were collected in Hong Kong. Sequence changes of the entire coding region of the RP1 gene were examined using PCR, conformation sensitive gel electrophoresis and DNA sequencing.Results. In total, 1 nonsense mutation and 1 nonsense variant as well as 10 missense alterations were identified in the RPl gene, among which, Arg677Ter was found in 1 RP patient and another nonsense variant, Argl933Ter, was identified in 3 normal individuals and 1 patient with Stargardt' s disease, suggesting its nonpathogenicity. Arg677Ter is expected to lead to large disruptions of the encoded protein.Conclusions. The nonpathogenicity of Argl933Ter indicates that the C - terminal 224 residues of RPl protein may be not critical for RPl. The most C - terminal truncation previously reported was due to Tyr1053 (1-bp del) and occurred in RP patients. Thus RP can be caused by reduction in

SCREENING FOR MUTATIONS IN A NOVEL RETINAL-SPECIFIC GENE AMONG CHINESE PATIENTS WITH RETINITIS PIGMENTOSA

Objective. To identify and evaluate mutations in the RPl gene among Chinese patients with retinitis pigmen-tosa (RP).Methods. Leukocyte DNA of 92 RP patients were collected in Hong Kong. Sequence changes of the entire coding region of the RP1 gene were examined using PCR, conformation sensitive gel electrophoresis and DNA sequencing.Results. In total, 1 nonsense mutation and 1 nonsense variant as well as 10 missense alterations were identified in the RP1 gene, among which, Arg677Ter was found in 1 RP patient and another nonsense variant, Argl933Ter, was identified in 3 normal individuals and 1 patient with Stargardt' s disease, suggesting its nonpathogenicity. Arg677Ter is expected to lead to large disruptions of the encoded protein.Conclusions. The nonpathogenicity of Argl933Ter indicates that the C - terminal 224 residues of RPl protein may be not critical for RP1. The most C - terminal truncation previously reported was due to Tyr1053 (1 -bp del) and occurred in RP patients. Thus RP can be caused by reduction in the level of the region of RPl protein after codon 1052 but before 1933. To ascertain such a proposition, genotypes of more RP patients may reveal more RP causative mutations and more sequence alterations different than those of other ethnic groups.