RecLOH is a term in

genetics Genetics is the study of genes, genetic variation, and heredity in organisms.Hartl D, Jones E (2005) It is an important branch in biology because heredity is vital to organisms' evolution. Gregor Mendel, a Moravian Augustinian friar worki ...

that is an abbreviation for " Recombinant Loss of

Heterozygosity Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...

". This is a type of

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, m ...

which occurs with DNA by recombination. From a pair of equivalent ("homologous"), but slightly different (

heterozygous Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...

) genes, a pair of identical genes results. In this case there is a non-reciprocal exchange of genetic code between the chromosomes, in contrast to

chromosomal crossover Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes' non-sister chromatids that results in recombinant chromosomes. It is one of the final phases of geneti ...

, because genetic information is lost.

For Y chromosome

In genetic genealogy, the term is used particularly concerning similar seeming events in

Y chromosome The Y chromosome is one of two sex chromosomes ( allosomes) in therian mammals, including humans, and many other animals. The other is the X chromosome. Y is normally the sex-determining chromosome in many species, since it is the presence or a ...

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 chromosomes An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes ...

, 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,

heterozygosity Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...

is lost. Recombination on the Y-chromosome does not only take place during

meiosis Meiosis (; , since it is a reductional division) is a special type of cell division of germ cells in sexually-reproducing organisms that produces the gametes, such as sperm or egg cells. It involves two rounds of division that ultimately ...

, but virtually at every

mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maint ...

when the Y chromosome condenses, because it doesn't require pairing between chromosomes. Recombination frequency even exceeds the frame shift mutation frequency ( slipped strand mispairing) of (average fast) Y-STRs, 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 ( hairpin). E.g. DYS459, DYS464 and DYS724 (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. DYS464X) 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 deletion. 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 DYS724) are affected by one and the same recLOH event.

References

*{{cite web , last = Krahn , first = Thomas , year = 2005 , url = http://www.dna-fingerprint.com/modules.php?op=modload&name=Sections&file=index&req=viewarticle&artid=9 , title = Recombinational Loss of Heterozygosity (recLOH) , publisher = DNA-Fingerprint, Germany , archive-url = https://web.archive.org/web/20101129015930/http://www.dna-fingerprint.com/modules.php?op=modload&name=Sections&file=index&req=viewarticle&artid=9 , accessdate = 2006-07-11 , archive-date = 2010-11-29

External links

RecLOH explained
Genetics Genetic genealogy

For Y chromosome

References

See also

External links