Comparison of twins (40 identical and 23 fraternal) for mathematics deficits (MD), in which at least one member had a mathematics disability, found evidence for a significant genetic etiology. However, tests for the differential etiology of MD as a function of reading performance level were nonsignificant. (Author/DB)

A study applied the polygenic threshold model to previously reported differences in gender ratios among children with reading disabilities and close family members with similar disabilities. The results were found to be predictable with the model. (MSE)

Siblings and parents of 39 children with dyscalculia were assessed for arithmetic, reading, and attention disorders. Findings indicated a familial prevalence of dyscalculia almost tenfold higher than expected for the general population and suggest that dyscalculia, like other learning disabilities, has a significant familial aggregation,…

This study examined 87 pedigrees of individuals with histories of preschool phonology disorders. Significantly more family members with dyslexia and learning disabilities, but not stuttering or hearing impairment, were found in pedigrees of individuals with phonology disorders than in pedigrees of nondisabled individuals. (Author/JDD)

This article summarizes work in progress at the Bowman Gray School of Medicine (North Carolina) on the structure and physiological profiles of reading disability and relates the findings to core left-hemisphere language functions. Data add evidence of the structural anomalies associated with dyslexia and evidence of its heritability, especially of…

Word recognition data from identical and fraternal twins and siblings (N=172) indicated that the phonological coding deficit of children with reading disabilities was highly heritable. Orthographic coding was not significantly heritable. Poor readers with low IQs were superior to similar reading but average IQ readers in phonological coding.…

This study of 640 twins with reading disability and 436 controls (mean age 12) examined external validity of the distinction between specific reading retardation and reading backwardness, in 3 domains: genetic etiology, sex ratio and clinical correlates, and neuropsychological profiles. There was no evidence of differential genetic etiology of the…

This article offers a historical overview of the neurological aspects of dyslexia (originally seen as related to aphasia) and a review of familial and genetic factors in developmental dyslexia. Psycholinguistic models of dyslexia as they relate to neurological concepts are presented and the evolution of successful remedial methods is summarized.…