Distribution of the FECH allelic mRNA ratios in 39 Caucasian controls. Data are presented as histogram of the observed distribution at 0.1 intervals and a polynomial tendency curve. According to the bimodal distribution, the 39 subjects could be separated into a main subgroup of 30 with equally expressedFECH alleles (mean, 1.02; 95% CI, 0.96 to 1.08) and a smaller group of 9 with a marked disequilibrium in their relative FECHmRNA allelic representation (mean, 0.59; 95% CI, 0.58 to 0.60). Haplotypes for the 9 low-expressed alleles were [G-T-A9-T] in 6 cases, [G-T-A9-C] in 2, and [A-C-A9-T] in 1.