What are Telomeres?

DNA is considered the building block of life and is found in nearly every cell of all living beings in small packages called chromosomes. In humans, each of our cells (except sex cells) contains 46 chromosomes. For an organism to grow and function properly, cells must divide to produce new cells to replace old, worn-out cells. During cell division, it is essential that chromosomes remain intact and evenly distributed among cells.

Telomeres are repetitive, non-coding stretches of DNA located at the ends of chromosomes and are a key part of the process that ensures DNA is accurately copied. They protect the ends of chromosomes in a manner similar to the way the tips of shoelaces keep them from unraveling. At every cell division, telomeres lose a bit of their DNA. When a cell is old and has lost much of its telomeric DNA the cell cannot replicate and dies. Thus, the loss of telomeric DNA with every cell division acts as an aging clock for the lifetime of the cell.

Telomere_Illustration
telomere-length-diagram3

How Telomere Diagnostics Determines Telomere Length

Although TDx’s products may ultimately integrate telomere measurements from multiple cell types, to date, our studies have utilized white blood cells to measure relative average telomere length (TL). Average TL by qPCR (quantitative polymerase chain reaction) is by far the simplest and most scalable assay for clinical applications.

For our products, we use the “Cawthon qPCR assay” for average TL [1; 2]. The foundational patent on this technology has been issued in the US and other countries, and TDx has the exclusive worldwide rights to it and related Cawthon patents.

Using telomere specific primers with our assay protocol, a sample having longer telomeres will yield quantitatively more product than a sample with shorter telomeres. The ratio of the telomeric signal vs. the single copy gene signal reflects the average length of the telomeres per cell in the sample. TDx has developed proprietary methods to tackle the sensitive nature of the qPCR telomere length assay with regards to sample collection, storage, preparation, and assay conditions. Telomere Diagnostics uses multiple standards and normalization procedures to ensure precision and accuracy of the assay, which is then used as a tool to evaluate many clinical applications.

[1] Cawthon, RM. Telomere measurement by quantitative PCR. Nucl. Acids Res. (2002) 30(10):e47.

[2] Cawthon, RM. Telomere length measurement by a novel monochrome multiplex quantitative PCR method. Nucl. Acids Res. (2009) 37(3):e21.