Rare Disorder of Sexual Differentiation with a Mosaic 46,XX/47,XXY in a Klinefelter Syndrome Individual

BACKGROUND: Klinefelter syndrome (KS) mosaicism 46,XX/47,XXY is an extremely rare disorder of sex development characterized by the presence of both ovarian and testicular tissues in the same individual. Both elements can be present in the same gonad (ovotestis) or separately in the same individual or as a unilateral ovotestis and the other side with testis or ovary. A mosaic with 46,XY would present with problems related to male infertility and in general, testicular insufficiency, but with a 46,XX mosaic, it is a completely rare presentation. As adolescents, these boys may experience severe emotional and behavioral issues; it is up to the parents to identify these conditions early and get them physician evaluated for possible abnormalities so that they can get the benefit of treatment. CASE PRESENTATION: A case of a rare disorder of sexual differentiation with a mosaic 46,XX/47,XXY in a KS individual is reported for whom karyotyping and SRY-FISH work-up was done. CONCLUSION: Early cytogenetic testing is essential to identify these individuals and testosterone replacement therapy and breast reduction for case management are helpful. Assisted reproductive technology (ART) may assist these individuals father children in some cases.