Ubiquitin ligase 3A ( UBE3A ) and GABA
receptor β3 ( GABRB3 ) levels positively correlate with imprinting center of the Prader-Willi locus (PWS-IC) methylation while small nucleoriboprotein N ( SNRPN ) levels negatively correlate with PWS-IC methylation. A significant positive correlation between PWS-IC methylation and UBE3A transcript levels was observed when all cases were grouped together (a) or for duplication of 15q11-q13 (dup15q) samples only (b). There was no significant correlation between percentage maternal allele-specific methylation at the PWS-IC and levels of UBE3A when cases were grouped separately without duplications as control or autism (Additional file 4). The percentage methylation of PWS-IC correlated with an increase in GABRB3 in all cases (c). When separated by diagnosis, however, the positive trend between GABRB3 and PWS-IC methylation in dup15q, control, or autism cases analyzed separately did not reach significance (Additional file 5). A significant negative correlation between SNRPN and PWS-IC methylation was observed for all cases (d); however, no significant correlation was observed for dup15q, control, or autism samples grouped separately for comparison of SNRPN and PWS-IC methylation (Additional file 6). Significance was calculated by a simple regression analysis. Diamond, dup15q; triangle, autism; square, control.