The genome-wide linkage results for the seven traits are illustrated in Figure 1 with the strongest linkage signals for each trait listed in Table 3. For quantitative traits SOC and BEH, no chromosomal region reached a LOD score of 2.2, the genome-wide suggestive linkage threshold. For the subset analyses, the most significant linkage signal was on chromosome 15q13.3-q14 for IQ ≥ 70 (LOD score = 4.01, p = .00001, δ [the locus-specific effect size] = .25) (Figure 2). Interestingly, there was also weak evidence for linkage for BEH at the same region (LOD score = 1.67, p = .003). The next strongest linkage signal was on chromosome 11p15.4-p15.3 for DelayedPhrase (LOD score = 3.40, p = .00004, δ = .19) (Figure 2). In this region, the LOD scores were 1.34 (p = .007) for DelayedWord, 1.89 (p = .002) for Verbal, and 2.15 (p = .0008) for IQ ≥ 70. There was also a LOD score of 2.18 (p = .0008) at this region when all the ASD families were used. The linkage results for individual chromosomes are provided in Figure 1 in Supplement 1.
