DNA Commission of the International Society of Forensic Genetics (ISFG): An update of the recommendations on the use of Y-STRs in forensic analysis

Forensic DNA Analysis

“…Since then, a large body of work has been published on structural aspects and population genetics of Y-STR loci, as well as on forensic applications (Roewer 2009), and scientific recommendations have been issued (Gusmao et al 2006). When testing body fluids in sexual assault cases with predominantly male perpetrators, a male-specific set of DNA polymorphisms such as Y-chromosomal STRs will enable the investigator to test evidence items such as vaginal swabs without interference of the female victim's DNA.…”

X-chromosome STR sequence variation, repeat structure, and nomenclature in humans and chimpanzees

“…Although no specific ISFG guidelines on the use of Xchromosome markers in forensics analysis are available, the existing recommendations concerning autosomal STRs and more specifically on Y-STRs can be extended to X-STRs regarding locus structure and allele nomenclature designation [2,6,11]. In the context of this work, we underline some of those main suggestions important for nomenclature discussion: (1) the identification of regions that vary and that may likely vary should be supported by sequence analysis of individuals from different human populations, as well as by comparison with chimpanzee sequences; (2) the first repetitive motif in a simple or complex sequence structure that encloses the highest number of repeats should be defined; (3) alleles must be named in agreement with the total number of adjacent variant and non-variant repeats obtained from sequence data analysis; (4) non-variant repeats should be included in the allele nomenclature if the number of nucleotides that separate these structures from the main variable repeat is equal or less to the number of nucleotides of the repeat unit; (5) if a previously established nomenclature of an STR is not in accordance with the ISFG guidelines but has been widely utilized, the nomenclature should not be altered to avoid unnecessary confusion.…”

“…The evident increase of studies in the literature justifies the necessity of a common nomenclature allowing for communication, data exchange, and data comparison among laboratories. The importance of establishing a common and accurate nomenclature has long been emphasized by several international DNA working groups (e.g., [2,6,11]), as well as by many other studies that use STRs located throughout the genome (e.g., [9,10,15,16]). Although many population-databased studies on X-STRs are available in the literature (e.g., [1, 3-5, 7, 8, 12, 18-20]), few have focused on the analysis of allele and locus sequence structure (e.g., [4,13,14,20]).…”

Genetic sub-structure in western Mediterranean populations revealed by 12 Y-chromosome STR loci

“…Allelic designation was based on comparison to the Powerplex® Y System allelic ladder. Allele nomenclature was according to the ISFG guidelines [16].…”

“…The International Society of Forensic Genetics (ISFG) recommended the use of regional Y-STR haplotype databases and the verification that no population sub-structure exists before pooling data from different regions [16]. It is especially important to evaluate genetic sub-structure in the western Mediterranean area, due to the existence of some geographical and/or cultural isolates such as Balearic populations [24,37] and Calabrian populations [36].…”