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	QTL-kartläggning	Transmission Disequilibrium Test
Ämnesområde	Genetik	Genetik
Familj	Process / pipeline	Process / pipeline
Ursprungsår	1989	1993
Upphovsperson	Eric Lander & David Botstein	Richard Spielman & Warren Ewens
Typ	Genetic linkage method	Hypothesis test
Ursprungskälla	Lander, E. S., & Botstein, D. (1989). Mapping Mendelian traits using RFLP linkage maps. Genetics, 121(1), 185–199.	Spielman, R. S., McGinnis, R. E., & Ewens, W. J. (1993). Transmission test for linkage disequilibrium. American Journal of Human Genetics, 52(3), 506–516.
Alias	QTL analysis, Linkage mapping, Trait locus mapping	TDT, Family-based association test
Närliggande	4	4
Sammanfattning	Quantitative trait loci (QTL) mapping is a genetic method that localizes chromosomal regions influencing quantitative traits—continuous phenotypes controlled by multiple genes and environmental factors. Developed by Lander and Botstein in 1989, QTL mapping uses linkage analysis and trait variation in segregating populations (such as F2 crosses or recombinant inbred lines) to identify genomic intervals containing loci that substantially affect trait values. This foundational approach has been extended to genome-wide association and is essential for understanding the genetic architecture of complex traits.	The Transmission Disequilibrium Test (TDT) is a family-based statistical method for testing genetic association with disease or traits while inherently controlling for population stratification. Developed by Spielman and Ewens in 1993, the TDT examines whether an allele is preferentially transmitted from heterozygous parents to affected children compared to unaffected children. By comparing transmission patterns within families, the TDT avoids the confounding effects of population structure that plague case-control studies, making it particularly valuable in admixed or stratified populations.