A genome-wide linkage and association scan reveals novel loci for autism

Top Cited Papers
Open Access
Publisher Website
Google Scholar
Abstract
Autism is a highly heritable neurodevelopmental disorder, and yet very few specific susceptibility genes have been identified to date. A genome-wide scan using half a million genome-wide SNPs (single nucleotide polymorphisms) in a common set of 1,031 multiplex autism families has now revealed significant linkage and association to autism. The linkage regions identified provide targets for rare variation screening while the discovery of a single novel association, between SEMA5A and TAS2R1 on chromosome 5p15. The expression of SEMA5A was found to be reduced in brains from autistic patients, further confirmation that it is an autism susceptibility gene. Autism is a highly heritable neurodevelopmental disorder, and yet few specific susceptibility genes have been identified to date. A linkage and association mapping study using half a million genome-wide single nucleotide polymorphisms is now described in a common set of 1,031 multiplex autism families. The linkage regions identified provide targets for rare variation screening whereas the discovery of a single novel association, SEMA5A, demonstrates the action of common variants. Although autism is a highly heritable neurodevelopmental disorder, attempts to identify specific susceptibility genes have thus far met with limited success1. Genome-wide association studies using half a million or more markers, particularly those with very large sample sizes achieved through meta-analysis, have shown great success in mapping genes for other complex genetic traits. Consequently, we initiated a linkage and association mapping study using half a million genome-wide single nucleotide polymorphisms (SNPs) in a common set of 1,031 multiplex autism families (1,553 affected offspring). We identified regions of suggestive and significant linkage on chromosomes 6q27 and 20p13, respectively. Initial analysis did not yield genome-wide significant associations; however, genotyping of top hits in additional families revealed an SNP on chromosome 5p15 (between SEMA5A and TAS2R1) that was significantly associated with autism (P = 2 × 10-7). We also demonstrated that expression of SEMA5A is reduced in brains from autistic patients, further implicating SEMA5A as an autism susceptibility gene. The linkage regions reported here provide targets for rare variation screening whereas the discovery of a single novel association demonstrates the action of common variants.