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1. Why Repeat Diagnostics?
Repeat Diagnostics is the only CLIA Certified telomere length measurement service in the world. The FLOW-FISH based measurements that Repeat Diagnostics offers are of higher accuracy than PCR and Q-FISH based measurements provided by other companies.
Repeat Diagnostics 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 under Information) 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.
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4. How is it done?
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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
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Clinical Laboratory Improvement Amendments (CLIA) ID number 99D1068060
California License LAB ID# COS 00800307
Maryland License #1651
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"Curiosity and prudence go hand in hand."
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