Recently, a study examining the effect of altered expression of 16p11.2 CNV region genes on zebrafish head size identified KCTD13 as the major driver of head size change, with MAPK3 and MVP named as possible modifiers49. These results motivated us to examine association of rs4583255[T] with expression of KCTD13, MAPK3, and MVP in human brain. Using data from three publicly-available data sets with at least 50 European-ancestry adult brains each (total N = 565)36-38, we found that rs4583255[T] was significantly associated with expression of MAPK3 (effect = 0.12 s.d., P = 0.011), but not significantly associated with expression of KCTD13 or MVP (Supplementary Table 7). We also investigated association of rs4583255[T] with gene expression in blood using data sets from Iceland (N=972)42 and the Netherlands (N = 437)39, 40. Consistent with the brain results, rs4583255[T] was significantly associated with higher expression of MAPK3 (for Iceland , P = 9.4 × 10−15; for the Netherlands, P = 0.014 for probe 3870601,and P = 0.042 for probe 234040), but not significantly associated with expression of KCTD13 or MVP.
