A GRAMMATICAL SPECIFIC LANGUAGE IMPAIRMENT IN CHILDREN - AN AUTOSOMAL-DOMINANT INHERITANCE

The aim of this study is to provide further characterization of a subg roup of so-called ''Grammatical specific language-impaired (SLI)'' chi ldren. The Grammatical SLI children have a persistent and disproportio nate impairment in grammatical comprehension and expression of languag e. Previous research has indicated that their language impairment may be characterized by a domain-specific and modular language deficit. Th is study provides an initial investigation as to whether there is a ge netic basis underlying their disorder as has been found for other form s of SLI and for SLI in general. The incidence of familial aggregation of language impairment was investigated in 12 Grammatical SLI childre n (aged 9:3 to 12:10). A familial language impairment (LI) history was classified as positive if one or more of the probands' relatives had a history of a speech/language or reading/writing problem which requir ed speech therapy or any other form of remedial help. Case history inf ormation provided an initial indication that the Grammatical SLI child ren had a significantly higher incidence of a positive familial LI his tory than could be expected by chance. A questionnaire provided eviden ce of a positive LI history in the first-degree relatives of the SLI p robands and 49 normally developing control probands. The SLI probands had a clearly and significantly higher incidence of a positive familia l LI history than the control probands (77.8 vs. 28.5%, respectively). The results are consistent with a genetic basis underlying Grammatica l SLI. The pattern of impairment in the SLI probands' relatives is con sistent with an autosomal dominant genetic inheritance. In contrast to the control probands, the SLI probands' impaired relatives did not sh ow a male gender bias. Thus, the gene does not appear to be sex-linked . The data indicate that further research is warranted to investigate the nature of the LI in the relatives of the Grammatical SLI probands and the genetic characteristics of this subgroup. The implications for the biological, domain-specific, and modular bases to language are di scussed. (C) 1996 Academic Press, Inc.