INFORMATION
General Information

Flow-FISH measurements have been shown to be valuable as a screening test for inherited telomere maintenance deficiencies resulting from mutations in dyskerin, telomerase RNA (hTERC), telomerase reverse transcriptase (hTERT) and other genes.

Deficiencies in these genes are known to predispose to a variety of clinical disorders including forms of aplastic anemia, pulmonary fibrosis, liver cirrhosis and dyskeratosis congenita. Distinction between acquired and inherited factors contributing to these and other diseases is important for prognosis and therapeutic considerations.

To get a general idea whether telomere length has been affected, we offer the BASIC PROCEDURE. This procedure provides measurements of telomere length for total lymphocyte and granulocyte populations.

In more specialized situations, however, this procedure may not be informative enough. E.g. in most aplastic anemia patients, the granulocyte telomere lengths will be low and lymphocytes may be borderline. When testing patients with diseases related to mutations in telomere maintenance genes, the DETAILED PROCEDURE is more appropriate. With this procedure, telomere lengths are measured not only for total lymphocyte and granulocyte populations, but also for B-cells, T-cells and NK cells.
Longer telomeres: more fluorescence.
Frequently asked questions:


1. Why Repeat Diagnostics?

2. Why telomere length measurements?

3. Why telomere length measurements by flow cytometry?

4. How is it done?

5. How can I learn more?

6. How much does it cost?

7. Is Repeat Diagnostics CLIA certified?


1. Why Repeat Diagnostics?

This company was set up as a spin-off from the British Columbia Cancer Agency (BCCA), when requests for telomere length measurements using the flow FISH technique overwhelmed the research laboratory of Dr. Peter Lansdorp, where this technique was developed and perfected.


2. Why telomere length measurements?

Requests for telomere length measurements are typically from physicians curious to know whether the clinical problems of their patients could be related to cellular defects resulting from extremely short telomeres. These defects may be caused by unknown stressors or inherited deficiencies in genes involved in telomere maintenance. In part, this interest is driven by several recent peer-reviewed scientific publications (see below) showing that telomere length measured by flow FISH can be used to identify individuals with various forms of inherited telomerase deficiency and to distinguish carriers of mutations in telomerase genes and in genes encoding telomere binding proteins from individuals without such abnormalities.

Apart from excluding inherited problems in telomere maintenance as a cause in bone marrow failure, dyskeratosis congenita, immune deficiencies, pulmonary fibrosis and cardiovascular diseases, telomere length information has also been used in the selection of siblings as possible bone marrow transplant donors for patients with bone marrow failure resulting from telomerase deficiency.

Furthermore, there are several papers linking short telomeres and telomere loss to stress and (predisposition to) various diseases including cardiovascular diseases and cancer.

Based on the above, the value of leukocyte telomere length in a variety of clinical settings needs to be explored in future studies. Areas of immediate interest are studies of telomere length in relation to disease predisposition and prognosis, diets and nutritional supplements and adverse effects to cytotoxic medications and treatments.


3. Why telomere length measurements by flow cytometry?

The Flow FISH technique is highly reproducible and accurate and more informative compared with other methods such as Southern Blot analysis of restriction fragments and PCR based techniques. This more informative technique allows analysis and comparisons of the telomere length between different cell types and within one cell type, e.g. in longitudinal studies. Such studies have shown that the telomere length declines with age, and following transplantation follows distinct patterns in T cells, B cells and hematopoietic precursor cells.

4. How is it done?
Telomere length analysis utilizing multicolor flow-FISH can be performed on subsets of human leukocytes from peripheral blood collected from individuals, in this case a DETAILED PROCEDURE for an 83 year old.

To obtain the flow cytometric histograms for the auto-fluorescence (b) and telomere fluorescence of each subset of cells, the following gating strategy is used:

1. Control cells (R1 + R4), lymphocytes (R2 + R4) and granulocytes can be distinguished based on their staining with the DNA dye LDS751 and on forward scatter and light scatter properties

2. The green fluorescence of cells gated in (a) hybridized in the absence (b) or presence (c) of fluorescein-labeled PNA probe is shown relative to LDS751 fluorescence

3. Antibodies specific for CD45RA and CD20 cells are used (e) to perform telomere length analysis of specific populations within the lymphocyte gate (R2 + R4)

4. Telomere length measurements (g) for a single individual will vary for each cell type from one individual

Welcome to Repeat Diagnostics

5. How can I learn more?


Click here to download and print an up-to-date list of related peer-reviewed scientific publications.

Follow the following links for more information on telomere science:

Telomeres in the NEWS

  • February 15, 2008, Blood, Vol. 111, No. 4, pp. 1759-1766:
    ASH 50TH ANNIVERSARY REVIEW on Telomeres, stem cells, and hematology

  • January 29, 2008, BBC NEWS: Sedentary life 'speeds up ageing'



    • Online Related Peer-Reviewed Scientific Publications

    1. Baerlocher, G. M., Vulto, I., de Jong, G. & Lansdorp, P. M. Flow cytometry and FISH to measure the average length of telomeres (flow FISH). Nat Protoc 1, 2365-76 (2006).

    2. Alter, B. P. et al. Very short telomere length by flow FISH identifies patients with Dyskeratosis Congenita. Blood (2007).

    3. Armanios, M. Y. et al. Telomerase mutations in families with idiopathic pulmonary fibrosis. N Engl J Med 356, 1317-26 (2007).

    4. Ly, H. et al. Functional characterization of telomerase RNA variants found in patients with hematologic disorders. Blood 105, 2332-9 (2005).

    5. Ly, H. et al. Identification and functional characterization of 2 variant alleles of the telomerase RNA template gene (TERC) in a patient with dyskeratosis congenita. Blood 106, 1246-52 (2005).

    6. Yamaguchi, H. et al. Mutations in TERT, the gene for telomerase reverse transcriptase, in aplastic anemia. N Engl J Med 352, 1413-24 (2005).

    7. Savage S.S.,Giri N, Baerlocher, G.M., Orr, N., Lansdorp P.M., and Alter, B.P. TINF2, a Component of the Shelterin Telomere Protection Complex, is Mutated in Dyskeratosis Congenita. Am. J. Hum. Gen. 82(2): 501-9 (2008).

    8. Fogarty, P. F. et al. Late presentation of dyskeratosis congenita as apparently acquired aplastic anaemia due to mutations in telomerase RNA. Lancet 362, 1628-30 (2003).

    9. Baerlocher, G. M., Rice, K., Vulto, I. & Lansdorp, P. M. Longitudinal data on telomere length in leukocytes from newborn baboons support a marked drop in stem cell turnover around 1 year of age. Aging Cell 6, 121-3 (2007).

    10. Rufer, N. et al. Accelerated telomere shortening in hematological lineages is limited to the first year following stem cell transplantation. Blood 97, 575-7 (2001).

    11. Rufer, N. et al. Telomere fluorescence measurements in granulocytes and T lymphocyte subsets point to a high turnover of hematopoietic stem cells and memory T cells in early childhood. J Exp Med 190, 157-67 (1999).



    Other Helpful Links

  • Dr. Peter M. Lansdorp's Flow FISH Laboratory


  • Search the telomere literature database


    • 6. How much does it cost?
    The flow FISH technique is labor intensive and involves sophisticated equipment, so the costs are generally higher than with the simpler, less informative PCR based techniques.

    Only the flow FISH technique generates accurate, reproducible, multi-parameter data.

    As fewer tests are required to establish significant differences in telomere length between test subjects and controls, the greater accuracy of the flow FISH technique can result in cost savings.
    "Invest in better, accurate and reproducible information."
    BASIC PROCEDURE (no antibodies)

    Telomere length is measured for total lymphocyte and granulocyte populations.

    DETAILED PROCEDURE (including antibodies)

    Telomere length is measured for total lymphocyte and granulocyte populations as well as in B-cells, T-cells and NK cells.
    This test is recommended for patients and their relatives, when inherited deficiencies in telomere maintenance are suspected. Such diseases include dyskeratosis congenita, aplastic anemia, pulmonary fibrosis, liver cirrhosis and other dysplastic disorders, caused by mutations in telomerase genes.

    For more information, or for pricing on research contracts, please contact us at info@repeatdiagnostics.com.

    7. Is Repeat Diagnostics CLIA certified?
    Yes, Repeat Diagnostics is certified by the Center for Medicare & Medicaid Services (CMS) under Clinical Laboratory Improvement Amendments (CLIA).

    CLIA ID number 99D1068060
    "Curiosity and prudence go hand in hand."