Gender Ratios in Children with Reading Disability and Their Affected Relatives: A commentary

that gender ratios (boys to girls) in sam-ples of children with reading disability (RD) exceeded those of their affected relatives. For example, in their family study of 59 boys and 10 girls (a ratio of 5.9 to 1) with reading and spelling test scores below expectation given IQ, age, and grade placement, the gender ratio for 45 siblings with RD was only about 2 to 1. Finucci and Childs suggested that the high gender ratios observed in samples of children with RD are due to biases of ascertainment, whereas family data pro-vide unbiased estimates: "Such biases of ascertainment can be eliminated by look-ing at the sex ratios of affected persons among sibs, since all of the latter will be ascertained solely by the presence of dyslexia in the index case " (Finucci & Childs, 1981, p. 5). The authors con-cluded that gender ratios in unbiased samples of children with RD may be 2 to 1 or less. Hallgren's (1950) classic family study of dyslexia was also cited by Finucci and Childs (1981) as an example of differen-tial gender ratios in children with RD and their affected relatives. Included in Hall-gren's study were 89 male and 27 female index cases, a ratio of 3.3 to 1. However, Hallgren deemed that 47 % of the 83 male siblings and 35 % of the 91 female siblings were affected. Moreover, 46 % of the 112 fathers and 38 % of the 112 mothers were diagnosed as dyslexic. Thus, affected siblings and parents mani-fested gender ratios of only 1.3 and 1.2 to 1, respectively. A final example cited by Finucci and Childs (1981) was their follow-up study of over 500 boys with RD who attende