Phenotypic homogeneity provides increased support for linkage on chromosome 2 in autistic disorder

A two-stage genomic screen analysis of 99 autistic disorder (AutD) families revealed suggestive evidence for linkage to chromosome 2q (D2S116 MLS (nonparametric sibpair LOD score) = 1.12 at 198 cM) (Shao 2001). In addition analysis of linkage disequilibrium (LD) for D2S116 showed an allelespecific P-value <0.01 (Bass 2000). Recently, Buxbaum et al. (2001) also reported linkage to the same 2q region (Heterogeneity LOD score (HLOD) = 1.96). Their evidence for linkage increased (HLOD = 2.99) when they restricted their analysis to the subset of AutD patients with delayed onset (> 36 months) of phrase speech (PSD). We similarly classified our data set of 99 AutD patients identifying 37 AutD families with PSD. Analysis of this PSD subset increased our support for 2q linkage (MLS of 2.82 and HLOD of 2.05 for D2S116). These data support evidence for a gene on chromosome 2 contributing to AD risk and suggest that phenotypic homogeneity increases the power to find susceptibility genes for AutD.

Duke Scholars

Author Allison Elizabeth Ashley-Koch Medicine, Nephrology