| Extended families of 12 former students in a rural school (9 learning disabled, 3 non-learning disabled) took a battery of academic tests and answered questionnaires on reading history, health, and handedness. Subtests providing the best separation between learning disabled (LD) and non-LD within these 131 subjects were the PIAT Spelling, WRAT Spelling, and PIAT Reading Recognition. While LD was strongly familial, specific types of disability were not, and the LD pattern could present as a deficit in math, reading, spelling, or a combination of these within the same family.;Autoimmune disorders were significantly correlated (p ;A small (n = 16 in each group) case-control sample of LD subjects, their non-LD family members, and non-LD non-family members showed the same test score patterns and correlation with autoimmune disorders, when matched for age and sex. A longitudinal followup of 3 subjects 15 years after their school testing demonstrated that persistence of LD occurs in only some individuals, and such persistence appears to be familial.;This study gives partial support to that portion of the Geschwind Hypothesis concerning a connection between immune disorders and LD, supports dominant inheritance of LD, but does not support familial transmission of specific LD subtypes.;Examination of the pedigrees and complex segregation analysis using POINTER confirmed that LD was genetically transmitted, with the most probable model in the 9 LD families being dominant or additive dominant inheritance. Multifactorial and recessive inheritance were less likely under POINTER. The population frequency of LD was estimated at 8%, and 73% of the proband's first degree relatives had LD. The level of LD-LD marriages was high (32%). |
