Supplemental figure 4 graphically illustrates the known genes located further upstream and downstream of the 18q23 GWAS signal found to interact (via HUGIn50) with rs12954372; including LINC01029 and SALL3 throughout different brain tissues, and ATP9B and MBP in embryonic stem cells. LINC01029 was recently associated with schizophrenia and nicotine dependence61, SALL3 with digit length ratio62 and modestly with AUD in the Genetic Analysis Workshop 14 dataset63 (includes a subset of COGA), ATP9B with prostate cancer64 and frontotemporal lobar degeneration65, and NFATC1 with Crohn’s and Inflammatory Bowel disease66, and creatinine levels67. While little is known about the function of most of these genes, much is known regarding MBP (Myelin Basic Protein) and its important role in neural connectivity. Myelin increases efficient neural signal transmission throughout the brain, and it is thought to contribute to the enhanced brain-regional connectivity, processing speed, and related cognitive function throughout the lifespan68. Subtle abnormalities of myelination can lead to persistent cortical network dysfunction68, which may provide one potential link to dysfunction in neurocognitive and psychiatric phenotypes.
