An epidemiogenetic study of typical retinitis pigmentosa in Japan--a preliminary report of nationwide, multicenter study]

We performed a nationwide, multicenter study of typical retinitis pigmentosa with reference to the inheritance patterns of the disease. A total of 253 probands were registered during two months of 1989, and an analysis of the parental consanguinity of 182 probands with the method of inbreeding coefficient enabled us to estimate the relative prevalence of genetic types; autosomal recessive trait: 47.6%; autosomal dominant trait: 17.3%; sporadic cases: 34.6%. A comparison of the results with previous studies has indicated a decrease in the prevalence of the autosomal recessive trait and an increase in the sporadic cases, as would be expected from the decrease in consanguineous marriages and offsprings in the past few decades in Japan. X-linked retinitis pigmentosa was rarely identified, but precise evaluation of its frequency needs further investigation.