ST8SIA2 and autism spectrum disorder: Haplotype narrowing in the 35 Australian pedigrees using an autosomal dominant model for a highly penetrant gene of large effect implicated a 2.5 Mb high priority region (90.32–92.82 Mb) [12], which contains 3 hypothetical genes and 5 protein coding genes, namely: SLCO3A1, ST8SIA2, CHD2, RGMA and MCTP2. Of these, the alpha-2,8-sialyltransferase 2 gene (ST8SIA2) – an enzyme responsible for protein glycosylation – has previously been implicated as a putative susceptibility gene for schizophrenia [13], and autism spectrum disorder (verbal subtype) [14].