Case report of apoptosis in testis of four AZFc-deleted patients: increased DNA fragmentation during meiosis, but decreased apoptotic markers in post-meiotic germ cells.

AZFc deletions of the Y chromosome are the major known genetic cause of spermatogenetic failure. Meiotic studies have shown a prevalence of synaptonemal complex fragmentation and an excess of early-stage sperm cells, suggesting that the maturation block could involve apoptosis. We present a prospective and observational study of apoptotic markers in the sperm of four AZFc-deleted patients and two non-obstructive azoospermic controls without an AZFc deletion.

Human and mouse ZFY genes produce a conserved testis-specific transcript encoding a zinc finger protein with a short acidic domain and modified transactivation potential.

Mammalian ZFY genes are located on the Y chromosome, and code putative transcription factors with 12-13 zinc fingers preceded by a large acidic (activating) domain. In mice, there are two genes, Zfy1 and Zfy2, which are expressed mainly in the testis. Their transcription increases in germ cells as they enter meiosis, both are silenced by meiotic sex chromosome inactivation (MSCI) during pachytene, and Zfy2 is strongly reactivated later in spermatids.

HSFY genes and the P4 palindrome in the AZFb interval of the human Y chromosome are not required for spermatocyte maturation.

Background: Recurrent AZFb deletions on the human Y chromosome are associated with an absence of ejaculated spermatozoa consequent to a meiotic maturation arrest that prevents the progression of germ cells to haploid stages. The extreme rarity of partial deletions has hampered the identification of the AZFb genes required for normal meiotic stages. The critical interval, refined by two overlapping deletions associated with full spermatogenesis (AZFc and b1/b3), measures over 4 Mb and contains 13 coding genes: CDY2, XKRY, HSFY1, HSFY2, CYORF15A, CYORF15B, KDM5D, EIF1AY, RPS4Y2 and four copies of RBMY.