Support for linkage of autism and specific language impairment to 7q3 fromtwo chromosome rearrangements involving band 7q31

Childhood autism is characterised by impairments in communication and recip rocal social interaction together with restricted/stereotyped interests, wh ich are evident before 3 years of age. Specific developmental disorders of speech and language (SDDSL) are characterised by impairment in the developm ent of expressive and/or receptive language skills which is not associated with intellectual, sensory, physical, or neurological impairment. Family an d twin studies indicate a substantial genetic component in the aetiology of both disorders, They also reveal increased rates of SDDSL in relatives of autistic individuals, suggesting that this phenotype can represent one mani festation of the genetic liability for autism. Modelling of the recurrence risk for autism and milder phenotypes, such as SDDSL, suggest that three or four epistatic loci may be aetiologically involved, A recently published l inkage study of an exceptional family with an apparently dominantly inherit ed SDDSL implicated chromosome band 7q31 as the site of the putative suscep tibility locus (SPCH1). This region of chromosome 7 also shows strong linka ge in multiplex families with autism. We present two individuals (one has a utism, the other SDDSL) with different, apparently balanced chromosome rear rangements involving a breakpoint at 7q31,3, Fluorescence in situ hybridisa tion was used to localise the breakpoints to an similar to 1 cM interval be tween CFTR and D7S643. Our findings may be of interest and relevance to the genetic aetiology of autism, and helpful in the search for susceptibility loci for SDDSL and autism. (C) 2000 Wiley-Liss, Inc.