Tuesday, November 9, 2010

Linkage disequilibrium (LD), linkage study

When the transmission of genotype at locus A is DEPENDENT on the genotype at another locus B.

bio.classes.ucsc.edu/bio107/Class%20pdfs/W05_lecture15.pdf

Random genetic drift is a stochastic process (by definition). One aspect of genetic drift is the random nature of transmitting alleles from one generation to the next given that only a fraction of all possible zygotes become mature adults. The easiest case to visualize is the one which involves binomial sampling error. If a pair of diploid sexually reproducing parents (such as humans) have only a small number of offspring then not all of the parent's alleles will be passed on to their progeny due to chance assortment of chromosomes at meiosis.


http://www.talkorigins.org/faqs/genetic-drift.html

Agreement in the types of data that occur in natural pairs. For example, in a trait like schizophrenia, a pair of identical twins is concordant if both are affected or both are unaffected; it is discordant if one of them only is affected. Likewise, the pairs might be non-identical twins, or sibs, or husband and wife, etc.


http://www.mondofacto.com/facts/dictionary?concordance


www-gene.cimr.cam.ac.uk/clayton/courses/florence05/lectures/linkage-lecture.pdf
“Genetic linkage analysis is a statistical method that is used to associate functionality of genes to their location on chromosomes.“ 
http://bioinfo.cs.technion.ac.il/superlink/

Neighboring genes on the chromosome have a tendency to stick together when passed on to offsprings.
Therefore, if some disease is often passed to offsprings along with specific marker-genes , then it can be concluded that the gene(s) which are responsible for the disease are located close on the chromosome to these markers.

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