Table 2  Sample sizes with 80% power by increasing number of SNP markers in case-control and case-parent studies   Assumptions: 5% minor allele frequency, 5% disease prevalence, complete linkage disequilibrium (D'=1), and 5% type I error rates for allelic test.
SNP, single-nucleotide polymorphism; ORA, odds ratio of heterozygotes under an additive model; CC, case-control study; CP, case-parent study.