of the ADH1C*2 protein isoform that has recently been investigated in 575 patients and 530 controls from the Irish Affected Sib Pair Study of Alcohol Dependence (IASPSAD) sample. The two marker haplotype comprised of markers rs1614972 and rs1693482 yielded evidence for association with alcohol dependence. Single marker analysis with rs1614972, however, produced no evidence at all. While the allele frequencies in Irish and German patients are the same, they differ between the Irish and German control samples; the allele frequencies between the German GWAS and the follow-up study being the same. This finding underlines the importance of sample homogeneity.
