Administration study of recombinant erythropoietin on the carriers of variant c.577del in EPO gene.

The issue of misjudgment in recombinant erythropoietin (rEPO) detection caused by the variant c.577del in human EPO gene has been found in recent years. Though the method of analyzing de-N-glycosylated erythropoietins (EPO) in blood samples was developed for identifying both EPO_p.Arg193AspfsTer28 (VAR-EPO) and rEPO, it cannot be applied without the evaluation of excreted samples. For this purpose, five heterozygous carriers of the variant c.577del were recruited in an administration study of rEPO. Urine and blood samples were collected at different times before and after subcutaneous injection with a single-dose of 50 IU/kg. The urine samples were analyzed for intact EPO, while the serum samples were analyzed for both intact and de-N-glycosylated EPO. A typical mixed band was detected in all blank and wash-out urine samples, which all displayed a similar result with rEPO abuse. For the analysis of intact EPO in serum samples, a typical mixed band was detected in the wash-out samples from day 1 to day 3, which could be identified as rEPO directly, while double-band was observed in other samples with inconclusive results. The result of de-N-glycosylated EPO in all serum samples showed two separated bands, and the ratioL/U decreased along with wash-out periods. Also, compared with the intact EPO analysis, a longer detection window without false positive results was obtained when analyzing de-N-glycosylated EPO. Analysis of de-N-glycosylated EPO is not only able to recognize the variant carriers directly but also able to detect rEPO abuse in the blood samples from the variant carriers with higher efficiency than the analysis of intact EPO.