The effect of the HapICE and intron 1 haplotypes on NRG1 isoform expression. (a) The HapICE 5 SNP risk haplotype GCGTG has a significant effect on type III isoform expression (ANCOVA F(2,69)=3.763, P=0.028; post-hoc LSD: P=0.013478 or 0.019014 (for 1 or 2 copies compared with 0 copies)) with mean expression values (±s.e.) for individuals (n) with 0 copies (n=34), 1 copy (n=32) or 2 copies (n=8) were 3.446±0.168, 4.048±0.173, 4.349±0.357, respectively. (b) The intron 1 haplotype CCC(14)G has a significant effect on type II expression (ANCOVA F(1,65)=4.051, P=0.048), with mean expression values (±s.d.) for individuals (n) with 0 copies (n=46) or 1 copy (n=26) were 1.18±0.56 and 1.49±0.56, respectively. No homozygotes for the CCC(14)G haplotype were observed.