Each targeted STR marker is specific to the chromosome on which it is located, thus the copy number of the STR marker can be diagnostic of the copy number of the chromosome. In an individual unaffected by a trisomy, two alleles of a chromosome specific STR are determined by the QF-PCR technique as two peaks in a 1:1 ratio. The observation of an extra STR allele as either a three-peak pattern in a 1:1:1 ratio or two peak pattern in a 2:1 or 1:2 peak ratio is diagnostic of the presence of an additional sequence, which in turn may represent an additional chromosome as in the case of a trisomy.
The Yourgene® QST*R Pregnancy Loss assay is CE-marked for in-vitro diagnostic (IVD) use for quantitative diagnosis of the six most common autosomal trisomies associated with pregnancy loss: trisomy 13 (Patau's syndrome), trisomy 15, trisomy 16, trisomy 18 (Edwards' syndrome), trisomy 21 (Down's syndrome) and trisomy 22. The kit also includes X and Y chromosome markers, as well as the TAF9L marker for the assessment of sex chromosome complement. The results obtained from Yourgene® QST*R Pregnancy Loss assay will determine the aneuploidy status of the fetus and may be useful in ongoing reproductive planning counselling and decision making.