Article Abstract:
A regression-based transmission/disequilibrium (TD)-type test for linkage of a marker locus and a quantitative trait locus has been proposed. Information on the parent-to-offspring transmission status of the associated allele at the marker locus is used. Independence of observations is not necessary, so analysis of pedigree data is possible, and adjustment can be made for covariates. Validity and statistical power of the test have been evaluated by simulating markers at varying recombination fractions from the disease locus.
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Article Abstract:
Molecular evidence supports a common, recent ancestor for variegate porphyria (VP) in Afrikaner families from South Africa. The study involved 132 people from 15 families, including 58 affected individuals. A high frequency of the R59W mutation appeared to be better explained by a founder effect than by multiple mutations on a common haplotype. The R59W mutation consists of a C to T change at nucleotide position 452, found in about 90% of South African VP patients.
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Article Abstract:
'Ancestral haplotype reconstruction' is a new statistical method developed for linkage disequilibrium mapping of disease genes. Haplotype distribution in affected individuals is compared to the distribution expected for descendants of a common ancestor who had a mutation in the disease gene. The method is best used with an isolated population in which the founder disease mutation occurred within about 25 generations or less.
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