RepeatDx offers both 2- and 6-panel tests, here we outline some of the advantages of ordering the 6-panel telomere test.

What telomere length tests are available?

There are a range of telomere length tests available, however, the clinical laboratory at RepeatDx conducts specialist Flow FISH telomere testing (fluorescence in situ hybridization with flow cytometry). This complex method offers highly accurate and reproducible results that are utilized by physicians and hospitals around the world.

The Flow FISH telomere length test used by RepeatDx has the unique advantage, when compared to other telomere length measuring protocols, that it can provide results from six cell types – all from one blood sample. 6-panel tests include telomere length results from B-cells, naïve and memory T-cells and NK cells in addition to the total lymphocytes and granulocytes (the latter two would be the only results shown in a 2-panel test).

To find out more about Flow FISH process at RepeatDx have a read of this blog.

Why order a 6-panel telomere test?

1.       To follow diagnostic guidelines

Telomere length measurements are used to support healthcare professionals to make accurate diagnoses. The 6-panel test has the highest clinical diagnosis sensitivity and specificity in the differential diagnosis of individuals with inherited bone marrow failure syndromes / telomere biology disorders (TBDs).

The Dyskeratosis Congenita and Telomere Biology Disorders: Diagnosis and Management Guidelines recommend that for a diagnosis of dyskeratosis congenita (DC) telomere lengths should be below the first percentile for age (measured by multicolor Flow FISH) in three of four lymphocyte subsets (naïve T-cells, memory T-cells, B-cells, NK cells) and granulocytes.

Studies have demonstrated that telomere lengths below the first percentile for at least three of four lymphocyte subsets have highest sensitivity and specificity for diagnosis of DC. Therefore, to support an accurate TBD diagnosis, a 6-panel telomere test should be considered (rather than a 2-panel) in order to provide the telomere results for each of the cell subsets required.

2.       More information is beneficial

With the same sample preparation, including the amount of blood collected, results can either be shown for two cell types, or six. For many physicians having access to additional information is the clear preference, and over the past two years we have seen the proportion of 6-panel telomere tests compared to 2-panel tests ordered reflect this.

The conditions that telomere length can help to diagnose are often rare diseases, and their manifestations can vary, making an accurate diagnosis complex. Having ready access to more in-depth information regarding the telomere length of individual cell types can help to differentiate between constitutional deficiencies and individual cell type deficiencies and ultimately aid a timely diagnosis.

Read more here about the importance of a correct diagnosis and how telomere testing can support this.

3.       To maximize efficiency

Although the 6-panel can be used as a follow-up test in situations where the 2-panel is inconclusive or doesn’t provide enough information, in order to maximize efficiency, the 6-panel can be ordered as a first-line test with rapid turn around time. This can help to reduce time to diagnosis for patients and healthcare teams.

Telomere length testing can be conducted alongside, or as a precursor to, genetic testing, which typically has a slower turn around time. Telomere length information can be important as there remains a significant proportion of individuals who have TBDs and short telomeres but for whom no genetic abnormality can be identified. Ordering the 6-panel telomere test ensures the maximum return in terms of information, and can help more effectively guide whether further testing would be indicated in that particular case.

One of the benefits of ordering a telomere test with RepeatDx is that we offer both 6-panel and 2-panel testing – providing increased options for physicians and healthcare professionals, enabling tailored patient care.

For more information on ordering a 2- or 6-panel telomere test from RepeatDx, take a look at this section of our website.

Sources

Alter, B., Giri, N., Savage, S., and Rosenberg, P. (2015). Telomere length in inherited bone marrow failure syndromes. Haematologica. 100, 49-54.

Alter, B., Rosenberg, P., Giri, N., Baerlocher, G., Lansdorp, P., and Savage, S. (2012). Telomere length is associated with disease severity and declines with age in dyskeratosis congenita. Haematologica. 97, 353-359.

Alter, B., Baerlocher, G., Savage, S., Chanock, S., Weksler, B.,Willner, J., Peters, J., Giri, N., and Lansdorp, P. (2007). Very short telomere length by flow fluorescence in situ hybridization identifies patients with dyskeratosis congenita. Blood. 110, 1439-1447.

Ferreira, M. S., Kirschner, M. Halfmeyer,I. et al. Comparison of flow‐FISH and MM–qPCR telomere length assessment techniques for the screening of telomeropathies. Annals of the New York Academy of Sciences. 2019. doi:10.1111/nyas.14248.

Gutierrez-Rodrigues F, Santana-Lemos BA, Scheucher PS, Alves-Paiva RM, Calado RT (2014) Direct Comparison of Flow-FISH and qPCR as Diagnostic Tests for Telomere Length Measurement in Humans. PLoS ONE. 9(11): e113747. https://doi.org/10.1371/journal.pone.0113747.

Khincha, P.P., Dagnall, C.L., Hicks, B., Jones, K., Aviv, A., Kimura, M., Katki, H., Aubert, G., Giri, N., Alter, B.P., Savage, S.A., Gadalla, S.M. Correlation of Leukocyte Telomere Length Measurement Methods in Patients with Dyskeratosis Congenita and in Their Unaffected Relatives. Int J Mol Sci. 2017, 18, 1765.

Savage, S. & Cook, E. Dyskeratosis Congenita and Telomere Biology Disorders: Diagnosis and Management Guidelines. (First ed.) 2015. Accessed at: https://teamtelomere.org/wp-content/uploads/2018/07/DC-TBD-Diagnosis-And-Management-Guidelines.pdf.