A genomewide screen for autism: Strong evidence for linkage to chromosomes2q, 7q, and 16p

Autism is characterized by impairments in reciprocal communication and soci al interaction and by repetitive and stereotyped patterns of activities and interests. Evidence for a strong underlying genetic predisposition comes f rom twin and family studies, although susceptibility genes have not yet bee n identified. A whole-genome screen for linkage, using 83 sib pairs with au tism, has been completed, and 119 markers have been genotyped in 13 candida te regions in a further 69 sib pairs. The addition of new families and mark ers provides further support for previous reports of linkages on chromosome s 7q and 16p. Two new regions of linkage have also been identified on chrom osomes 2q and 17q. The most significant finding was a multipoint maximum LO D score (MLS) of 3.74 at marker D2S2188 on chromosome 2; this MLS increased to 4.80 when only sib pairs fulfilling strict diagnostic criteria were inc luded. The susceptibility region on chromosome 7 was the next most signific ant, generating a multipoint MLS of 3.20 at marker D7S477. Chromosome 16 ge nerated a multipoint MLS of 2.93 at D16S3102, whereas chromosome 17 generat ed a multipoint MLS of 2.34 at HTTINT2. With the addition of new families, there was no increased allele sharing at a number of other loci originally showing some evidence of linkage. These results support the continuing coll ection of multiplex sib-pair families to identify autism-susceptibility gen es.