CONTEXT: Although a rare occurrence, previously undiagnosed disorders of sex 
development (DSD) with hyperandrogenism are sometimes detected by hormonal 
screening during the international sports competitions. Identifying the cause of 
XY,DSD raises medical and ethical concerns, especially with regard to issues of 
the eligibility to compete.
OBJECTIVE: The aim of this study was to determine whether the detection of high 
plasma T in young elite female athletes during hormonal screening would reveal 
an unsuspected XY DSD.
SETTING: The study was performed in the Nice and Montpellier University 
Hospitals (France), which collaborate as reference centers for DSD in elite 
athletes on behalf of sports governing bodies.
PATIENTS: Four cases of elite young athletes with female phenotypes but high 
plasma T detected during hormonal screening were investigated for undiagnosed XY 
DSD.
MAIN OUTCOME MEASURES: Evaluation of clinical, biological, radiological 
(magnetic resonance imaging and dual-energy x-ray absorptiometry) and genetic 
characteristics was conducted.
RESULTS: The 4 athletes presented as tall, slim, muscular women with a male bone 
morphotype, no breast development, clitoromegaly, partial or complete labial 
fusion, and inguinal/intralabial testes. All reported primary amenorrhea. The 
hormonal analysis evidenced plasma T within the male range, the karyotype was 
46, XY, and molecular analysis of the 5α-reductase type 2 (srd5A2) gene 
identified a homozygotic mutation in 2 cases, a heterozygotic compound in 1 
case, and a deletion in 1 case.
CONCLUSION: 5α-Reductase deficiency should be investigated in elite young female 
athletes with primary amenorrhea and high male T levels detected during 
antidoping programs to identify undiagnosed XY DSD.