## Abstract The admixture test for the detection of linkage under heterogeneity is considered. We show that the null distribution of this test statistic has half its weight concentrated on zero and the other half on a complicated distribution that can be approximated by max (__X__~1~, __X__ ~2~ ) w
Power of the admixture test to detect genetic heterogeneity
β Scribed by Dr. Steven A. Narod; G. P. Vogler
- Publisher
- John Wiley and Sons
- Year
- 1991
- Tongue
- English
- Weight
- 483 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0741-0395
No coin nor oath required. For personal study only.
β¦ Synopsis
Several dominant genetic diseases which appear to be homogeneous are the expression of genetic mutations at several loci. The power to detect linkage by likelihood methods is diminished for heterogeneous, as compared to genetically homogeneous, disorders. Using a simulation approach and two pedigrees typical of those available for the study of a dominant disease (with expected lod scores of 0.43 and 1.00 at theta = 0.05 and PIC = .59), I have evaluated the power to detect genetic heterogeneity by using the admixture test. Linkage power was determined by varying the number of families available for study, the recombination fraction (theta), the informativity of the hypothetical marker, and the proportion of linked families, alpha. For moderate and small values of alpha it is feasible to detect genetic heterogeneity once linkage has been established; rarely will it be possible to detect linkage and heterogeneity simultaneously given a limited number of small or moderate pedigrees.
π SIMILAR VOLUMES
Due in part to an influential paper by Risch and Merikangas [(1996) Science 273:1516-1517], which suggested that disequilibrium tests would have greater power to detect genes of small effect than would linkage tests, interest in the use of the Transmission Disequilibrium Test (TDT) as an analysis to
Linkage analysis under the two-locus model and the admixture model was compared on pedigree data for a common disease simulated under a model of genetic heterogeneity. The ascertainment of families was designed so that the samples had a large proportion of families segregating for both disease loci.
## Abstract A major reason for the slow progress in identifying susceptibility genes for complex diseases may be that the clinical diagnoses used as phenotypes are genetically heterogeneous. This has led researchers to collect various phenotypes related to the diagnosis, such as detailed symptoms,
## Abstract There have been many single nucleotide polymorphismβbased tests suggested for association analysis in a caseβcontrol design. The possible evidence for association comprises three types of information: differences between cases and controls in allele frequencies, in parameters for Hardy