. Author manuscript; available in PMC: 2009 Oct 5.

Published in final edited form as: Hum Hered. 2006 Nov 15;62(4):196–212. doi: 10.1159/000096995

Table 2.

E(GTA) reflects a marker’s importance in the presence of gene-gene interactions

Within-class changes of penetrance due to Mr	Classes defined by M_q			E(GTA(r))	Importance of M_r
Within-class changes of penetrance due to Mr	Ω₀	Ω₁	Ω₂	E(GTA(r))	Importance of M_r
1 No class w. change	same	same	same	positive	low
2 One class w. change	change	same (+ or −)	same (− or +)	positive	low
3 One class w. change	change	same (+ or −)	same (+ or −)	negative	high
4 Two classes w. change	change	change	same	negative	high
5 Three classes w. change	change	change	change	negative	high

The computation is based on a simplifying assumption that all high risk genotypes share a same penetrance and all low risk genotypes also share a same penetrance. The difference between case 2 and 3 is that in case 2, M_q is dominantly more important than M_r, much so that including M_r will only add noises to the signals due to M_q. For case 3, M_q does not have such major effects and relatively M_r is important. Future investigation is needed to allow GTA pick up signals from M_r even when a dominating major gene such as M_q is present.