Welcome to ChrX-STR.org

This is the start of a new web-database covering many issues concerning the usage of

x-chromosomal markers for forensic purpose.
 

Ø Go to the ChrX STR via 
           idiogram

Ø Go to the ChrX STR via 
          the linkage table

Ø Go to STR clusters via ChrX-
           idiogram

Ø Diallelic ChrX-markers
          (a project of the future)

Ø      Ethical considerations

Ø submit data

Ø Calculate ChrX STR
           parameteres

Ø      Glossary

Ø useful links

Ø    ChrX users

Ø ChrX bibliography

Chromosome X (ChrX) genotyping can complement the analysis of autosomal (AS) and Y-chromosomal (ChrY) markers very efficiently, especially in complex cases of kinship testing.
These insights which rose in the late nineties and during the first years of the current decade induced increasingly investigations on ChrX markers for forensic usage. In contrast to forensic autosomal STRs and Y-chromosomal STRs ChrX markers are Introduction to forensic-ChrX-research poorly reviewed in the world wide web so far.
The goal of this page is to provide a database for ChrX STRs and ChrX STR haplotypes comprising population data published for some populations from several countries. However, we do not claim to present a complete literature review.
Mainly, this page contains data, which have been published in peer reviewed scientific journals. However, scientist can submit data on population samples of interest, when the quality requirements are fulfilled. Decision in regard with publication is reserved to the forensic ChrX research board. The course of law is excluded.
In contrast to CHRY markers, which do not recombine during meiosis for AS markers and ChrX markers the genetic localisation is an important issue when used in kinship testing. Since all ChrX markers are located on the same chromosome within an area of 240cM an exact knowledge on genetic localisation of ChrX markers is required. Genetic location of established forensic markers is displayed at the ChrX STR linkage table and the ChrX idiogram.

In kinship testing typing of ChrX STR clusters provides a powerful tool, when the arrangement of STR alleles in the linked STRs can be recognised as haplotypes. With the very rare exception of males showing the Klinefelter syndrome this applies always to the male sex. In addition, pedigree analysis frequently enable to estimate the haplotypes also in a female individual. Thus, we will present here haplotype frequencies in several populations for selected STR clusters. Please be aware, that very closely linked markers regularly exhibit a linkage disequilibrium. Hence, frequencies of haplotypes cannot be calculated by multiplication of the single alleles of the haplotypes involved but they must be estimated by the analysis of population samples.
Owing to some special genetic properties of the ChrX in some rare cases ethical problems during the ChrX typing may arise. Some remarks behind the button ethical considerations can help to avoid critical situations.

To learn more about our page click Introduction to forensic-ChrX-research.