Frequency of tuberous sclerosis in San-in district (Japan) and birth weight of patients with tuberous sclerosis

Abstract

Fifty-two patients with tuberous sclerosis including 44 propositi were collected from 11 hospitals and 20 institutions in the San-in district. Of the 52 patients 44 were alive at the time of the study and the prevalence of tuberous sclerosis among the general population of the San-in district in October 1979 was estimated to be one in 31,000 (3.2 x 10(-5)), which was the highest value among the surveys in certain geographical areas. The frequency of tuberous sclerosis in live-births was estimated to be one in 24,000 (4.0 x 10(-5)). The frequency of the sporadic cases in live-births was one in 31,000 (3.2 X 10(-5) and the mutation rate was directly estimated to be 1.6 X 10(-5) per gene per generation. A difference between the parental age or birth order of the sporadic cases and those of controls was not detected. The mean birth weight for the tuberous sclerosis group was 2,834 g which was slightly less than the 2,985 g for their normal sibs. The frequency of low birth weight, less than 2,500 g, among the children with tuberous sclerosis was 30% (7/23), which was 4 times that in the general population (P less than 0.005). These facts suggest that the intrauterine growth is affected in a considerable number of the patients.