Fig. 2  The statistical power according to the number of single-nucleotide polymorphism (SNP) markers for the allelic test in (A) a case-control study and (B) a case-parent study (a1 = 0.05, a2 = 1×10-7, and a3 = 5×10-8 denote the significance thresholds according to the number of markers; A1.3, A1.5, A2, and A2.5 denote the odds ratios of heterozygotes). MAF, minor allele frequency; D', linkage disequilibrium.