POPULATION GENETIC-STUDIES OF RETINITIS PIGMENTOSA

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 32  (2) , 223-235
Abstract
A questionnaire survey characterized a sample of 670 probands with retinitis pigmentosa (RP) and allied disorders. Segregation analysis provided some evidence for a small proportion of sporadic cases and for decreased segregation ratios of the dominant and recessive genotypes, which could be attributed to delayed age of onset in some cases. The overall incidence of RP was indirectly calculated to be approximately 1 in 3700, while the incidence of autosomal recessive RP, including at least 2 genocopies, was estimated to be about 1 in 4450. Family data analysis included the calculation of the likelihood that each family represented autosomal recessive, autosomal dominant and X-linked inheritance patterns. These likelihoods were than converted to relative probabilities and summed over the sample population to yield estimates of the proportions of the 3 Mendelian types. This large, heterogeneous sample indicated that .apprx. 84% of the cases in the USA are autosomal recessive, while about 10% are dominant and 6% X-linked recessive.