To characterise genetic variation that may quantitatively impact formation of PSA-NCAM, we performed massively parallel sequencing on the 454 GS-FLX platform of two regions that we hypothesise are associated with ST8SIA2-related developmental pathology in mental illness: 1) a ∼95 kb region including the entire coding and intronic regions and ∼20 kb of flanking sequence of ST8SIA2 (hg19/GRCh37: chr15∶92,919,255–93,013,920 bp; Figure 1); and 2) a ∼6 kb region within NCAM1 (hg19/GRCh37: chr11∶113,100,972–113,107,571 bp; Figure 2). Here, NCAM1 is linked to psychiatric disorder.