Table 2

The family-based case-control design: Transmitted alleles (cases) and nontransmitted alleles (controls) from 2N parents with one affected child

Marker allele Total
MM*
Cases
 Observed number a b a + b = 2N
 Expected frequency Embedded Image Embedded Image 1/2
Controls
 Observed number c d c + d = 2N
 Expected frequencyQ/2(1 − Q)/21/2
Observed numbera + cb + d4N