Figure 1

Schematic of three-stage study design for linkage analyses. Linkage analyses were performed using a three-stage approach. (1a) A discovery sample (Stage 1) and (1b) previous linkage results were used to identify loci of suggestive linkage (logarithm of odds (LOD) ≥2.2). (2) These suggestive loci were tested for linkage in an extended sample. (3) For loci achieving genome-wide significant linkage (LOD ≥3.6) in either the discovery, extended, or previously published studies, the non-overlapping subset of families was tested for independent replication of linkage. AGRE, Autism Genetics Resource Exchange; SNP, single nucleotide polymorphism.