Background: Males with a 47,XXY karyotype have the clinical phenotype of Klinefelter syndrome. A few 47,XXY cases with a female phenotype have been reported. These individuals have positive SRY (testis-determining factor). The genetic explanation of this phenomenon is unclear.
Case: A 34-year-old woman presented with testicular feminization and a 47,XXY karyotype. Cytogenetic analysis and fluorescence in situ hybridization suggested that the Y chromosome had a normal structure; the polymerase chain reaction was positive for SRY.
Conclusion: This is the third reported case of 47,XXY with afemale phenotype in spite of the presence of a Y chromosome and the normal SRY. This suggests that the phenotypic sex in these patients might be due to the involvement of other sex-determining genes.