Analysis of 12 X-STRs loci in a population from southeastern Brazil.

Short tandem repeat (STR) markers on the X chromosome have a high potential for solving complex kinship analysis and individual identification cases. To achieve such purposes, allele and haplotype frequencies for the specific population are necessary. Nonetheless, such frequencies are not always available. Therefore, we obtained haplotypes from 520 unrelated males from four different geographic regions of Espírito Santo - Brazil, using the Investigator Argus X-12 kit. Forensic parameters for linked groups of four X-STR loci are reported. Genetic distance analyzes suggest that ES population is genetically closer to the Italian population and farther from the Mexican one, among the populations analyzed in this study.

Forensic Applications of Markers Present on the X Chromosome.

Microsatellite genetic markers are the gold standard for human genetic identification. Forensic analyses around the world are carried out through protocols using the analysis of STR markers in autosomal chromosomes and in the Y chromosome to solve crimes. However, these analyses do not allow for the resolution of all cases, such as rape situations with suspicion of incest, paternity without a maternal sample for comparison, and biological traces with DNA mixture where the profile sought is female, among other situations. In these complex cases, the study of X-chromosome STR markers significantly increases the probability of identification by complementing the data obtained for autosomal and Y-chromosome markers, due to the unique structure of the X chromosome and its exclusive method of inheritance. However, there are currently no validated Brazilian protocols for this purpose, nor are there any population data necessary for statistical analyses that must be included in the issuance of expert reports. Thus, the aim of this article is to provide a literary review of the applications of X-chromosomal markers in population genetics.