Discovery of c.577del in EPO: Investigations into endogenous EPO double‐band detected in blood with SAR‐PAGE. Issue 4 (22nd November 2021)

• Record Type: Journal Article
• Authors: Zhou, Xinmiao; He, Sen; Zezhou, Li; Jiayu, Wang; Zhou, Wen; Liu, Xinchao; Zhao, Meiping; Zhang, Lisi
• Is Part Of: Drug testing and analysis. Volume 14:Issue 4(2022)
• Page Start: 622
• Page End: 633
• Publication Date: 2021-11-22
• Subjects: doping -- erythropoietin -- mutant EPO -- variant; Drugs -- Analysis -- Periodicals; Drug testing -- Periodicals; Chemistry, Forensic -- Periodicals; 615.1901
• DOI: 10.1002/dta.3200
• Languages: English
• ISSNs: 1942-7603

Abstract

Abstract: Recently, some athletes were repetitively found to have rEPO positive results, including a characterized double‐band pattern in blood samples, in routine doping analysis. In contrast to previous findings from excretion studies, this double‐band pattern showed the same relative intensity even when the samples were collected weeks (/months) apart. We therefore suspected that these "positive" doping control samples were related with a novel pathway of endogenous EPO production. Thus, follow‐up investigations were warranted to characterize the origin of such analytical test results and to avoid the issuing of adverse analytical findings in the absence of rEPO by identifying the root cause of these "constantly positives." In this study, we designed and conducted a series of causal studies, including population screening of EPO profiles, exploration of EPO de‐N‐glycosylation, single nucleotide polymorphism (SNP) browsing in EPO, sequencing of EPO exons, genealogical analysis of the c.577del EPO variant, and finally expression and investigation of mutant EPO. In summary, we found that these "constantly positives" were related to endogenous EPO production associated with the c.577del EPO variant. The frequency of this variant was 0.39% in our Chinese population pool. The mutant EPO encoded by this variant is 27 amino acids longer than the wild‐type. The molecular weight of this mutant EPO is approximately the same as that of rEPO, exhibiting a similar electrophoretic behavior. To prevent charges against carriers of the c.577del variant, a revised rEPO testing strategy has been implemented in the new version of TD EPO. Abstract : The c.577del EPO variant, which can result in the production of a mutant EPO, is reported in this study. The molecular weight of this mutant EPO is approximately the same as that of recombinant EPO, showing a similar electrophoreitc behavior, the use of which is considered doping in sports. To prevent charges against carriers of the c.577del variant, a revised rEPO testing strategy has been implemented in the new version of TD EPO.