Anybody have this test done? Labo & tests - our scienceConfirmation test Quantitative Measurement of RNase L Proteins: The Confirmatory Test to Aid in the Diagnosis of Chronic Fatigue Syndrome Chronic Fatigue Syndrome (CFS) is recognized as one of the most common chronic illnesses in the world. CFS is a complex disease syndrome of unknown etiology, afflicting people of all ages. Currently CFS is defined by its symptoms(1), the hallmark of which is chronic, debilitating fatigue of six months or more in duration. In addition, patients suffer from a number of physical problems including myalgia, arthralgia, cognitive impairment, and sleep disorders. Emergence of a Possible Diagnostic Marker In 1995, Dr. Robert Suhadolnik and his co-workers at Temple University, Philadelphia, PA, detected a novel intracellular protein related to RNase L, one of the interferon-inducible enzymes. These enzymes, which also include 2'-5' Oligoadenylate Synthetase, and double-stranded RNA dependent Protein Kinase, play a key role in protecting the cell from viral infection.(2,3) The novel protein was determined to have a molecular weight of approximately half of the native RNase L (and is thus referred to as the Low Molecular Weight RNase L or 'LMW,' while the native RNase L protein is referred to as the High Molecular Weight (HMW) species). Working together with clinicians Daniel Peterson and Paul Cheney, Dr. Suhadolnik was able to demonstrate the presence of this LMW protein in a subset of patients with CFS.(4,5) His findings were independently confirmed by Dr. Bernard Lebleu, at the Institute for Genetic Molecular Medicine, Montpellier University, Montpellier, France, working together with clinician Kenny De Meirleir at the Free University of Brussels, Belgium.(6) Development of a Clinical Assay In 1998, R.E.D. Laboratories began offering the assay for the RNase L LMW protein. The assay is performed by 1) preparation of a cytoplasmic extract of the patient's peripheral blood mononuclear cells, 2) combination of this extract with a labelled probe that binds specifically to 2'-5'A-binding proteins such as RNase L and the LMW species, 3) SDS-polyacrylamide gel electrophoresis, and 4) densitometry to determine the relative quantities of 2'-5'A-binding proteins (see Figure 1 below). Results & Interpretation Results are quantified with normal reference ranges provided. A numerical value is calculated by densitometry as "the amount of LMW protein present divided by the amount of native (HMW) RNase L present" multiplied by a factor of 10 (or (LMW/HMW) x 10). Preliminary data indicate the following: Negative: Ratio <0.1 - 1.9 XXXXX Positive: Ratio = 2.0 or more (Please note: The results of this test should be used in addition to all other relevant clinical data before making a diagnosis and/or a recommendation for treatment. Ranges are subject to change dependent on future data.) This test was developed and its performance characteristics determined by R.E.D. Laboratories. It has not been cleared or approved by the U.S. Food and Drug Administration (FDA). The FDA has determined that such clearance or approval is not necessary. This test is used for clinical purposes. It should not be regarded as investigational or for research. References 1. Holmes, G., et al., "Chronic Fatigue Syndrome: A Working Case Definition," Annals of Internal Medicine 108:387-389 (1988). 2. Suhadolnik, R., et al., "Changes in the 2-5A Synthetase/RNase L Antiviral Pathway in a Controlled Clinical Trial with Poly(I)-Poly(C12U) in Chronic Fatigue Syndrome," In Vivo 8:599-604 (1994). 3. Suhadolnik, R., et al., "Upregulation of the 2'-5'A Synthetase/RNase L Antiviral Pathway Associated With Chronic Fatigue Syndrome," Clinical Infectious Disease 18:S96-S104 (1994). 4. Suhadolnik, R., et al., "Biochemical Evidence for a Novel Low Molecular Weight 2'-5'A-Dependent RNase L in Chronic Fatigue Syndrome," Journal of Interferon & Cytokine Research 17:377-385 (1997). 5. Suhadolnik, R., et al., "Biochemical Dysregulation of the 2'5A Synthetase/RNase L Antiviral Defense Pathway in Chronic Fatigue Syndrome," Journal of Chronic Fatigue Syndrome 5:223-242 (1999). 6. De Meirleir, K., et al., "A Novel 2'-5'A Binding 37 kDa RNase L as a Biochemical Marker for Chronic Fatigue Syndrome," American Journal of Medicine 108: 99-105 (2000).