First Case of Sperm Detection by Testicular Sperm Extraction in a Patient With XXY/XX Mosaicism

Klinefelter syndrome (KS) is a chromosome disorder characterized by small firm testes, gynecomastia, hypogonadism, and abnormally elevated concentrations of follicle-stimulating hormone (FSH). Most KS patients show a classic 47,XXY karyotype, while about 20% have other numeric sex chromosome abnormalities, including mosaicisms. 47,XXY/46,XX mosaicism is extremely rare, and has been reported in just 10 individuals with features suggestive of KS. None of these had any spermatozoa in their ejaculate or testicular samples. We describe the first case of sperm retrieval in a 19-year-old male patient with a 47,XXY/46,XX chromosomal pattern, assessed on 100 metaphases. Since 2 semen analyses had shown azoospermia, the patient underwent surgical testicular sperm extraction (TESE): Numerous primary spermatocytes, spermatids, and spermatozoa with normal morphology and nonlinear motility were found in the right testis, while few spermatocytes and rare immobile spermatozoa were observed in the left testis. Immediate cryopreservation of the sample was performed in our sperm bank for future use in assisted reproductive technology. This case underscores the rarity and complexity of this genetic condition and highlights the importance of early fertility assessment and intervention in patients with a 47,XXY/46,XX karyotype.