The triangle test statistic (TTS) : a test of genetic homogeneity using departure from the triangle constraints in IBD distribution among affected sib-pairs
Dizier, M.H.; Quesneville, H.; Prum, B.; Selinger Leneman, H.; Clerget Darpoux, F.
Annals of Human Genetics 64(5): 433-442
ISSN/ISBN: 0003-4800 DOI: 10.1046/j.1469-1809.2000.6450433.x
The proportions of affected sibs sharing 2, 1 or 0 identical by descent parental marker alleles have been shown to conform to the 'triangle constraints' (see Suarez, B. K. Tissue Antigens (1978) 12, 87-93: Holmans, P. American Journal of Human Genetics (1993) 52 362-374). It has also been shown that the constraints are verified provided certain assumptions hold. In this study we explore a realistic situation in which the constraints fail due to the presence of a factor in which the sibs differ, a factor on which penetrance depends. This factor may be a characteristic of the trait (severe vs. mild form), or the presence/absence of an associated trait or an environmental factor.