Pregnancy Loss

Miscarriage is defined as the spontaneous loss of pregnancy before the fetus reaches viability and includes all pregnancy losses from the time of conception until 24 weeks of gestation. Recurrent miscarriage is the loss of three or more consecutive pregnancies and affects nearly 1% of couples trying to conceive.

50% of first trimester recurrent miscarriage cases have been shown to be caused by a chromosome abnormality. The most commonly noted abnormality group is the trisomies, which account for 60% of all chromosomal disorders observed in products of conception. Within this group, the most frequently observed trisomy is chromosome 16. Trisomy of chromosomes 13, 15, 18, 21 and 22 are also commonly seen. Other aneuploidies commonly seen include monosomy X, and triploidy. These account for approximately 20% and 15% of all abnormalities respectively.

Traditionally, products of conception (POC) samples were analysed using standard cytogenetic techniques. These techniques, involving tissue culture and microscopic analysis, can take up to 14 days to provide a diagnosis. In particular, fluorescent in situ hybridisation (FISH), using interphase cells is expensive, time consuming and unsuitable for high throughput use.

The Yourgene® QST*R Pregnancy Loss assay takes advantage of the Quantitative Fluorescence-Polymerase Chain Reaction (QF-PCR) technology to provide results in less than 24 hrs from sample receipt, without the need for cell cultures. PCR amplification uses fluorescent dye labelled primers to target highly polymorphic regions of DNA sequence and short tandem repeats (STRs), located on the chromosomes of interest.

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.

The Yourgene® QST*R Pregnancy Loss assay is compatible with most commonly employed DNA extraction protocols, thermal cyclers and capillary electrophoresis instruments.

This flexibility in approach is complemented by simple and easy to use analysis software for reporting. Results can be analysed through either Life Technologies GeneMapper™ or SoftGenetics GeneMarker® software.

GeneMarker’s® operation now includes a customised Trisomy Analysis function. By selecting BPG (Best Practice Guidelines) settings within the Trisomy Analysis function users can quickly and accurately measure allele ratios to obtain a full patient sample report within minutes.