A twin study of Bannatyne's "genetic dyslexic" subtype.

Bannatyne's proposed "genetic dyslexic" subtype of reading disability (RD) was evaluated using data obtained from 60 (30 monozygotic and 30 dizygotic) pairs of affected twins (in which at least one member of each pair has a reading disorder) and 60 pairs of control twins. The predicted spatial greater than conceptual greater than sequential pattern of means was found to be reliable and specific to the RD sample. While this study does not provide conclusive evidence on the genetic etiology of the proposed subtype, our results do indicate that individuals with this particular profile may constitute a specific subtype of reading disability.