The 41 TelVysion probes are specific to:

•  p and q subtelomeres of chromosomes 1-12 and 16-20
• q subtelomeres of the acrocentric chromosomes (13, 14, 15, 21, and 22)
• Xp/Yp and Xq/Yq pseudo-autosomal region subtelomeres
• A unique region within 300 kb of each chromosome telomere

The probes in ToTelVysion are provided in 15 mixtures. All probes are direct labeled, providing bright signals with minimal background noise. By utilizing SpectrumOrange, SpectrumGreen, SpectrumAqua, and a combination of SpectrumOrange and SpectrumGreen (to yield a yellow signal), each probe within a mixture is labeled with a unique color.

Vysis TelVysion Probes

Telomeres are DNA-protein complexes that cap the ends of eukaryotic chromosomes. Every telomere contains 3 to 20 kb of tandem TTAGGG repeats. The telomere associated repeats (TAR), also known as the subtelomeric repeats, are immediately proximal to the TTAGGG repeats. They contain regions of shared homology between subsets of certain chromosomes. Each TelVysion targeted site is a unique, chromosome specific DNA located approximately 100 to 300 kb from the chromosome end.

Schematic Of The Make-Up Of Human Chromosome Telomeric Regions

In the context of constitutional chromosome analysis, the most distal region of unique DNA on a chromosome arm commonly is referred to as the "subtelomere." Subtelomeres are known to contain a high concentration of genes as compared to other chromosome regions. Yet, subtelomere abnormalities can be difficult, if not impossible, to detect by routine G-band analysis because subtelomeres stain negative (light). Diagram courtesy of C. Lese and D. Ledbetter, University of Chicago.