Frequency and heterogenity of the Klinefelter syndrome among azoospermic male populations in Arab countries for 10 years period (2015–2025)

Background: Klinefelter syndrome (KS) is a major chromosomal cause of severe male infertility, particularly non-obstructive azoospermia, and represents the most frequent sex chromosome aneuploidy among azoospermic men worldwide. While individual studies from Arab countries have reported variable KS frequencies and described both classic and mosaic karyotypes, no prior systematic review has comprehensively examined its burden and mosaic patterns across the Arab populations. This systematic review summarizes studies that investigated the frequency of KS and reported mosaic KS karyotype subtypes among azoospermic Arab men. Study design: A systematic literature search was conducted in PubMed and Google Scholar in July 2025 using predefined keywords related to KS, azoospermia, and Arab populations, restricted to original research articles published between 2015 and 2025. Eligible studies included azoospermic men from Arab League member states and reported the frequency of KS and, when available, mosaic variants, with data extracted and grouped into three regional blocks: Arabian Peninsula, Fertile Crescent, and African Arab countries. Results: Out of 5568 records identified, 18 articles from 10 Arab countries met the inclusion criteria, encompassing 4534 azoospermic men. Across all included studies, 620 patients were diagnosed with classic non-mosaic KS, corresponding to an overall frequency of 13.67%, with regional frequencies of 6.7% in the Arabian Peninsula, 13.65% in the Fertile Crescent, and 15.37% in African Arab countries. Mosaic KS was reported in 15 patients across fuve studies, predominantly the 46,XY/47,XXY karyotype, along with other rare triple mosaic forms. Conclusion: KS emerges as a major and often underrecognized chromosomal aneuploidy among azoospermic Arab men, with an overall frequency comparable to global estimates and notable regional variability. The identification of both classic and mosaic KS patterns underscores the need to integrate routine karyotyping into the diagnostic workup of azoospermic men and to implement multicenter, standardized studies that incorporate clinical, hormonal, and detailed karyotype data to refine genotype–phenotype correlations in Arab populations.