Cellmark provides an ISO 17025 accredited Y-STR profiling service using the informative 23 STR marker system PowerPlex^® 23 (PPY23). Y-STR profiling examines short tandem repeat (STR) markers that are only present on the male Y chromosome. Although less statistically informative than standard autosomal STRs, it is a highly sensitive forensic technique and, because it specifically targets male DNA, it is particularly useful for detecting and analysing a male suspect’s DNA in a sample that contains a mixture of male and female cellular material. It is also a very useful technique for determining the number of men that have contributed to a mixed sample, as well as for linking male relatives.

An individual's Y-STR profile is inherited from father to son so that all male descendants have essentially the same Y-STR profile. It is therefore a very useful technique for relationship analysis: for linking, or excluding, male relatives. PPY23 includes two rapidly mutating Y-STR loci to assist with differentiating close male relatives.

In sexual offence investigations, it is not uncommon for samples to have a mixture of male and female DNA, particularly with intimate swabs taken from a female complainant. When a mixed sample contains only trace levels of male DNA and a very large amount of female cellular material, this can have the effect of masking the male DNA if analysed using autosomal STRs.

Y-STR Enhancement Now Accredited

Cellmark has received ISO17025 accreditation from UKAS for the DNA Enhancement of forensic Y-STR profiles (PPY-23). Developed by Cellmark, DNA Enhancement can significantly increase the strength of low-level forensic DNA profiles, resulting in increased detection sensitivity. DNA Enhancement of Y-STR profiles can initially double the strength of a low-level profile while further enhancement stages can produce a six-fold increase in DNA profile strength. This has the potential to reveal DNA information that otherwise might not have been detected.

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