A French national-level cyclist underwent a urine doping control, and an Adverse Analytical Finding (AAF) was reported for recombinant EPO (rEPO), resulting in an immediate provisional suspension. Between the analyses of the A and B samples, the French Anti-Doping Agency conducted an additional analysis of EPO on a blood sample using the same SDS-PAGE method to exclude the expression of the EPOc.577 variant, which was not identified. Simultaneously, a urine sample was collected showing an Atypical Finding (ATF). The young cyclist was tested five times over the following 17 months, with all urine results considered as ATF, without the athlete being notified of these results. Seventeen months after the start of the suspension, it was discontinued. The robustness of the SDS-PAGE technique may be questioned in terms of its absolute reliability when used in urine doping controls to detect recombinant EPO. In this case, the test cost an athlete 17 months of his sporting career, which only lasts a few years. Due to the particularity of this case, a complementary biological and genetic study was proposed. NGS analysis of the erythropoiesis and iron regulation genes identified a heterozygous C282Y mutation in the HFE gene, with an elevated plasma ferritin level (200 μg/L). This genetic and phenotypic state is now documented, particularly in aerobic athletes. Given that we now know that the oxygen (EPO) and iron pathways are closely linked, further studies are needed to determine whether there might be a potential link between the HFE mutation, elevated ferritin levels, and the unreliability of the SDS-PAGE test for detecting EPO in urine.