A heterogeneity-based genome search meta-analysis for autism-spectrum disorders

Autism and autism-spectrum disorders exhibit high heritability, although specific susceptibility genes still remain largely elusive. We performed a heterogeneity-based genome search meta-analysis (HEGESMA) of nine genome scans on autism or autism-spectrum disorders. Each genome scan was separated in 30 cM bins and the maximum linkage statistic from each bin was ranked. Significance for each bin's average rank and for between-scan heterogeneity (dis-similarity in the average ranks) was obtained through Monte Carlo tests. For autism, data from 771 affected sibpairs were synthesized across six separate genome scans. Region 7q22 - q32 reached genome-wide significance both in weighted and unweighted analyses, with evidence for significantly low between-scan heterogeneity. The flanking chromosomal region 7q32-qter reached the less stringent threshold of suggestive significance, with no evidence for low between-scan heterogeneity. For autism-spectrum disorders ( 634 affected sibpairs from five separate scans), no chromosomal region reached genome-wide significance. However, suggestive significance was reached for the chromosomal regions 17p11.2 - q12 and 10p12 - q11.1 in weighted analyses. There was evidence for significantly high between-scan heterogeneity for the former region. The meta-analysis suggests that the 7q22 - q32 region should be further scrutinized for autism susceptibility genes, while autism-spectrum disorders seem to have quite diverse linkage signals across scans, possibly suggesting genetic heterogeneity across subsyndromes and subpopulations.