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# Table 1 Population and Sampling Frequencies of Case-Parent Trios. "F, M, C" refers to Father, Mother, Child.

Actual Observable
F, M, C Genotype Population Frequencya Case Frequencyb F, M, C Genotype Population Frequencya Case Frequencyb Label
2, 2, 2 p 4 p4/M P, P, P p2(3 - 2p) p2(1 + 2r1(1 - p))/M a
2, 1, 2 p3(1 - p) p3(1 - p)/M
2, 1, 1 p3(1 - p) r1p3(1 - p)/M
1, 2, 2 p3(1 - p) p3(1 - p)/M
1, 2, 1 p3(1 - p) r1p3(1 - p)/M
1, 1, 2 p2(1 - p)2 p2(1 - p)2/M
1, 1, 1 2p2(1 - p)2 2r1p2(1 - p)2/M
1, 1, 0 p2(1 - p)2 r0p2(1 - p)2/M P, P, D p2(1 - p)2 r0p2(1 - p)2/M b
2, 0, 1 p2(1 - p)2 r1p2(1 - p)2/M P, D, P p(1 - p)2 r1p(1 - p)2/M c
1, 0, 1 p(1 - p)3 r1p(1 - p)3/M
1, 0, 0 p(1 - p)3 r0p(1 - p)3/M P, D, D p(1 - p)3 r0p(1 - p)3/M d
0, 2, 1 p2(1 - p)2 r1p2(1 - p)2/M D, P, P p(1 - p)2 r1p(1 - p)2/M e
0, 1, 1 p(1 - p)3 r1p(1 - p)3/M
0, 1, 0 p(1 - p)3 r0p(1 - p)3/M D, P, D p(1 - p)3 r0p(1 - p)3/M f
0, 0, 0 (1 - p)4 r0(1 - p)4/M D, D, D (1 - p)4 r0(1 - p)4/M g
1. Note: M = p2 + 2r1p(1 - p) + r0(1 - p)2. The allele frequency of the full allele is denoted by p.
2. aUnder the assumption of Hardy-Weinberg equilibrium.
3. bUnder the assumption of Hardy-Weinberg equilibrium, and a risk of r0 (r1) for a child with zero copies (one copy) of full allele relative to the risk to a child with two copies of the full allele.