Only three tag SNPs showed evidence of allelic associations with X-ALD phenotypes at a 0.05 significance level (Table 1): rs973742 G/A (χ2 = 7.6; P = 0.006; empirical P = 0.008) located 4-kb downstream from the 3′ region of CD1D; rs3181082 C/T (χ2 = 5.3; P = 0.028; empirical P = 0.031) and rs2317955 G/T (χ2 = 4.4; P = 0.043; empirical P = 0.054) which are in LD (r2 = 0.96), and located in the upstream region of CD1B (at 1- and 14-kb respectively). This evidence concerns the gene CD1B and X-linked adrenoleukodystrophy.