A Genetic Study of Rheumatic Fever Clustering in Families

Abstract

SummaryThe first-degree relations of 433 rheumatic propositi were examined for evidence of rheumatic fever (RF) or rheumatic heart disease (RHD). The families of 470 control propositi were examined in identical fashion. Of the total propositi, 378 propositi were matched with 378 control propositi for sex, age group, and ethnic community (European or Afro-Asian origin). Of 738 sibs of rheumatic propositi, 19.6% had RF or RHD and of 586 sibs of controls, 3.1% had RF or RHD (P<0.001).In the matched families 2,985 first-degree relations of the propositi were examined: 142 had RF and 141 had RHD, a total of 9.5%. In the members of the families of the rheumatic propositi 232 rheumatics were found in 1,486 first-degree relations (15.6%), while in the control families 51 rheumatics were found among 1,499 (3.4%).Comparisons and analyses were made of expected and observed numbers according to sibship size using the method of truncated analyses (Lenz-Hogben method). This analysis supported the hypothesis of a simple mendelian recessive inheritance. Unbiased estimates of P, the population frequency of affected individuals, were consistent with the value P = 0.25, expected for a mendelian recessive character. The rheumatic fever clustering in families in this study was compatible with a simple recessive mendelian inheritance.