The XA TriScore (X/Y/21) mix of specific probes allows detecting copy number variations for chromosomes X, Y, and 21. The probe mix is composed of repetitive sequences which hybridize to the centromeric region of chromosomes X in blue (aqua) and Y in green. The orange labeled probe hybridizes to a region at 21q22 including the DSCR4 (Down syndrome critical region 4).

Probe maps for selected products have been updated. These updates ensure a consistent presentation of all gaps larger than 10 kb including adjustments to markers, genes, and related elements. This update does not affect the device characteristics or product composition. Please refer to the list to find out which products now include updated probe maps.

Probe map details are based on UCSC Genome Browser GRCh37/hg19, with map components not to scale.

Numerical aberrations of autosomes 13, 18, 21, and sex chromosomes X and Y account for 95% of birth defects in newborns. FISH applied to uncultured amniocytes provides a method to identify those aberrations much faster than conventional chromosome analysis. It has become a standard to provide preliminary results for the detection of anomalies in less than 12 hours.

Duplications of chromosome bands 21q22.13-q22.2 have been shown to define the smallest region implicated in the causation of Down syndrome. Repetitive sequences around the centromeric region of the X and Y chromosomes can reliably determine Klinefelter syndrome (47,XXY), Triple-X syndrome (47,XXX), Turner syndrome (45,X0), and 47,XYY. This probe also allows to differentiate male fetal cells from maternal cells in blood contaminated amniocyte samples.

XA TriScore (X/Y/21) hybridized to lymphocytes. Two aberrant interphases (47,XY,+21) are shown.

• Bryndorf et al (1996) Am J Hum Genet 59:918-926
• Tepperberg et al (2001) Prenat Diagn 21:293-301
• Stumm et al (2006) Cytogenet Genome Res 114:296-301