A second association signal of interest from the primary analyses (Table 2 and Supplementary Material, Table S2) involves a missense variation in the TAF1C gene (rs4150167; G523R; P = 1.0 × 10−6). TAF1C (TATA box-binding protein-associated factor 1C) is involved in the initiation of transcription by RNA polymerase I. This process requires the formation of a complex composed of the TATA-binding protein (TBP) and three TBP-associated factors (TAFs) specific for RNA polymerase I. TAF1C and its complex are displaced by PTEN (33). Mutations in PTEN have been highlighted in a number of cases of autism and related disorders (34–39). A caveat about the data for this SNP is worth noting: visual inspection revealed typical genotype clusters, yet the relatively common allele (≈0.98) is over-transmitted, a pattern consistent with poor genotyping quality.
