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RecLOH is a term in geneticsWp globe tiny.gif that is an abbreviation for "RecombinationWp globe tiny.gifal Loss of HeterozygosityWp globe tiny.gif".

This is a type of mutationWp globe tiny.gif which occurs with DNAWp globe tiny.gif by recombinationWp globe tiny.gif. From a pair of equivalent ("homologous"), but slightly different genes, a pair of identical genes results. In this case there is an unreciprocal exchange of genetic code between the chromosomes, in contrast to chromosomal crossoverWp globe tiny.gif, because genetic information is lost.

For Y chromosome

In genetic genealogyWp globe tiny.gif, the term is used particularly concerning similar seeming events in Y chromosomeWp globe tiny.gif DNA. This type of mutation happens within one chromosome, and does not involve a reciprocal transfer. Rather, one homologous segment "writes over" the other. The mechanism is presumed to be different from RecLOH events in autosomal chromosomesWp globe tiny.gif, since the target is the very same chromosome instead of the homologous one.

During the mutation one of these copies overwrites the other. Thus the differences between the two are lost. Because differences are lost, heterozygosityWp globe tiny.gif is lost.

Recombination on the Y chromosomeWp globe tiny.gif does not only take place during meiosisWp globe tiny.gif, but virtually at every mitosisWp globe tiny.gif when the Y chromosome condenses, because it doesn't require pairing between chromosomes. Recombination frequency even exceeds the frame shift mutation frequency (slipped strand mispairingWp globe tiny.gif) of (average fast) Y-STRWp globe tiny.gifs, however many recombination products may lead to infertile germ cells and "daughter out".

Recombination events (RecLOH) can be observed if YSTR databases are searched for twin alleles at 3 or more duplicated markers on the same palindrome (hairpinWp globe tiny.gif). E.g. DYS459, DYS464 and DYS724Wp globe tiny.gif (CDY) are located on the same palindrome P1. A high proportion of 9-9, 15-15-17-17, 36-36 combinations and similar twin allelic patterns will be found. PCR typing technologies have been developed (e.g. DYS464XWp globe tiny.gif) that are able to verify that there are most frequently really two alleles of each, so we can be sure that there is no gene deletionWp globe tiny.gif. Family genealogies have proven many times, that parallel changes on all markers located on the same palindrome are frequently observed and the result of those changes are always twin alleles. So a 9-10, 15-16-17-17, 36-38 haplotype can change in one recombination event to the one mentioned above, because all three markers (DYS459, DYS464 and DYS724Wp globe tiny.gif) are affected by one and the same recLOH event.

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This page uses content from the English language Wikipedia. The original content was at RecLOH. The list of authors can be seen in the page history. As with this Familypedia wiki, the content of Wikipedia is available under the Creative Commons License.
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