From: GCORE-sib: An efficient gene-gene interaction tool for genome-wide association studies based on discordant sib pairs
Case
A
a
B
4n 11 + 2n 12 + 2n 21 + n 22
4n 13 + 2n 12 + 2n 23 + n 22
b
4n 31 + 2n 32 + 2n 21 + n 22
4n 33 + 2n 32 + 2n 23 + n 22