Aim: To evaluate the occurrence of classical azoospermia factor (AZF) deletions of the Y chromosome as a routine examination in azoospermic subjects with Klinefelter syndrome (KS).

Methods: Blood samples were collected from 95 azoospermic subjects with KS (91 subjects had a 47,XXY karyotype and four subjects had a mosaic 47,XXY/46, XY karyotype) and a control group of 93 fertile men. The values of testosterone, follicle stimulating hormone (FSH) and luteinizing hormone (LH) were measured. To determine the presence of Y chromosome microdeletions, polymerase chain reaction (PCR) of five sequence-tagged site primers (sY84, sY129, sY134, sY254, sY255) spanning the AZF region, was performed on isolated genomic DNA.

Results: Y chromosome microdeletions were not found in any of the 95 azoospermic subjects with KS. In addition, using similar conditions of PCR, no microdeletions were observed in the 93 fertile men evaluated. The level of FSH in KS subjects was higher than that in fertile men (38.2 10.3 mIU/mL vs. 5.4 2.9 mIU/mL, P < 0.001) and the testosterone level was lower than that in the control group (1.7 0.3 ng/mL vs. 4.3 1.3 ng/mL, P < 0.001).

Conclusion: Our data and review of the published literature suggest that classical AZF deletions might not play a role in predisposing genetic background for the phenotype of azoospermic KS subjects with a 47,XXY karyotype. In addition, routine screening for the classical AZF deletions might not be required for these subjects. Further studies including partial AZFc deletions (e.g. gr/gr or b2/b3) are necessary to establish other mechanism underlying severe spermatogenesis impairment in KS.

Keywords: Y chromosome, chromosome deletion, Klinefelter syndrome, azoospermia

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