View Full Version : What are the low recombination regions of the X-chromosome?

12-04-2020, 07:20 AM
I've read of something like that in papers, but what regions exactly have this low level of recombination universally? Obviously in males there's only one X-chromosome, but female cells randomly deactivate the other X-chromosome early on.

For example this:
https://www.researchgate.net/publication/12978526_DNA_sequence_variation_in_a_non-coding_region_of_low_recombination_on_hman_X_chrom osome

If these regions exist, couldn't they be used to detect haplotypes and create haplogroups like in mtDNA and y-DNA?

12-05-2020, 01:20 PM
Looks like there has been a study on this!

We reasoned that by identifying genetic markers on human X chromosome regions where recombination is rare or absent, we should be able to construct X chromosome genealogies analogous to those based on Y chromosome and mitochondrial DNA polymorphisms, with the advantage of providing information about both male and female components of the population.

Methodology/Principal Findings
We identified a 47 Kb interval containing an Alu insertion polymorphism (DXS225) and four microsatellites in complete linkage disequilibrium in a low recombination rate region of the long arm of the human X chromosome. This haplotype block was studied in 667 males from the HGDP-CEPH Human Genome Diversity Panel. The haplotypic diversity was highest in Africa (0.9920.0025) and lowest in the Americas (0.8390.0378), where no insertion alleles of DXS225 were observed. Africa shared few haplotypes with other geographical areas, while those exhibited significant sharing among themselves. Median joining networks revealed that the African haplotypes were numerous, occupied the periphery of the graph and had low frequency, whereas those from the other continents were few, central and had high frequency. Altogether, our data support a single origin of modern man in Africa and migration to occupy the other continents by serial founder effects. Coalescent analysis permitted estimation of the time of the most recent common ancestor as 182,000 years (56,700–479,000) and the estimated time of the DXS225 Alu insertion of 94,400 years (24,300–310,000). These dates are fully compatible with the current widely accepted scenario of the origin of modern mankind in Africa within the last 195,000 years and migration out-of-Africa circa 55,000–65,000 years ago.

A haplotypic block combining an Alu insertion polymorphism and four microsatellite markers on the human X chromosome is a useful marker to evaluate genetic diversity of human populations and provides a highly informative tool for evolutionary studies.