Risk Factors / Causes > The Role of Genetics in Children's Language Disorders

Description of study: Our research into the genetics of developmental language impairment (LI) began in the late 1980s with research showing that language problems run in families. Our initial work asked if parental reports of speech and language problems were more common in children who had language problems than among children who did not have such problems. We found that there was an elevated rate of parental reported language problems in the near relatives of children with LI (Tomblin, 1989).

We followed this study with another study in which we directly tested the language skills of family members of individuals with LI. Again, we found that LI was common in these families, particularly among the fathers and brothers of the LI family member (Tomblin, 1994; Tomblin, 1996).

Having determined that LI did run in families, we conducted a study of LI in twins to determine if the familial characteristic of LI was based in genetic factors of the family or the environmental factors. Our twin research demonstrated that it was both genetic and environmental, but that genes were playing a strong role (Tomblin, 1996; Tomblin & Buckwalter, 1998).

These findings then led us to begin to look for specific genes that might be related to LI. To date we have not located a gene, however, we have found that a gene (FOXP2) that has been associated with LI in one family is not likely to contribute to LI in very many children. We did find evidence that a gene near FOXP2 may play a role in language development (O'Brien E.K., Zhang, Nishimura, Tomblin, & Murray, 2003; Tomblin, 1996; Tomblin et al., 1998).

Future work: We have been awarded additional federal funding to continue our research on the genetics of language impairment. This work will involve following recent findings from our lab and others regarding genes or genetic loci that appear to be associated with individual differences in language development. We are currently working with two members of the "TB family" who exhibit severe developmental speech and language impairment and also have a chromosomal translocation that appears to involve the FOXP2 gene. We are beginning to see strong evidence that some of the cognitive features of this genetic condition may involve implicit learning. We believe that implicit learning may be associated with difficulties in grammatical abilities. Work with the TB family will help guide some of our work with the families who have been participating in our longitudinal study. With additional funding, we can perform genome wide linkage studies using phenotypic information that we have gotten from the children in our longitudinal study along with their siblings. We also hope to return to these family members in order to obtain more measures of language and cognitive abilities now that they will all be adults.

Language and Genes: A Tutorial: This article, authored by Dr. Tomblin, appears in Nature Encyclopedia of the Human Genome, copyright 2003 Macmillan Publishers Ltd., Nature Publishing Group.

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