The genetic aspects of developmental dyslexia.

Abstract

This paper reviews the evidence that there are important genetic influences on developmental dyslexia, a disorder characterized by difficulty in learning to read despite adequate opportunity and intelligence. There is particular emphasis on the heritability of three major subtypes of dyslexia: (a) a subtype based on verbal/language deficiencies, perhaps reflecting reversed cerebral asymmetry; (b) a subtype based on visual/spatial deficiencies; and (c) a subtype based on both types of deficiencies. It is concluded that there is strong evidence for the heritability of the verbal/language subtype, but somewhat weaker evidence for the heritability of the other two subtypes mentioned. Further investigation into the genetics of dyslexia subtypes is necessary.