Left-handedness and immune disorders in familial dyslexics
B. F. Pennington, S. D. Smith, W. J. Kimberling, P. A. Green and M. M. Haith
We examined the frequency of left-handedness, various immune disorders, and
comparison disorders in 87 dyslexics and 86 nondyslexics from 14 extended
dyslexic families. These families were participants in our genetic linkage
studies of dyslexia, which found linkage to chromosome 15 in some families
but not others. In the present study, we found a significant elevation of
both autoimmune and allergic disorders in the dyslexics only, but no
elevation in mixed- or left-handedness in either group. Moreover, the
frequency of immune disorders was not higher in the mixed- or left-handed
subjects. There was also no elevation in the comparison disorders, which
argues against an overreporting bias. The elevation of immune disorders did
not vary with linkage status, arguing against a common cause for dyslexia
and immune disorders. These findings are discussed in light of Geschwind's
hypothesis of a testosterone-mediated association within families between
left-handedness, immune disorders, and dyslexia.
