Familial patterns of learning disabilities.

Extended families of 12 young adults (9 LD, 3 non-LD) were given a battery of tests and questionnaires, and 131 persons, ranging in age from 6 to 85, were classified as LD or non-LD on the basis of subtest scores 1 SD below the mean or less on subtests of the PIAT and WRAT achievement tests. Pedigree analysis indicated that LD was strongly familial, with the most probable mode involving a major gene effect, but the type of disability (reading/ math) was not directly inherited. Autoimmune disorders were significantly correlated (P<.005) with LD, especially in families in which LD remained a major handicap into adulthood, a trait that also varied between families. In two of the LD families, adults showed little evidence of the reading/spelling deficits they had shown when tested as children, while adults in other families failed to make gains in reading and spelling.