The Y chromosome: male reproduction and beyond.

The crucial role of Y chromosome genes in male gonadal determination and reproductive fitness has been recognized for decades. Y chromosome microdeletions are the most common molecular genetic causes of azoospermia and severe spermatogenic impairment. Since the late 1990s, screening for these microdeletions has become a routine part of the diagnostic work-up of severe male factor infertility. In this article, we provide a concise overview of the Y chromosome's structure and gene content. We describe its clinically relevant alterations, detectable through karyotyping or molecular genetic tools, with a focus on their phenotypic impact and significance for genetic counseling. Finally, we discuss the broader implications of Y chromosome variations on health conditions beyond male infertility.