Transmissible microdeletion of the Y-chromosome encompassing two DAZ copies, four RBMY1 copies, and both PRY copies.

Objective: To study a transmissible partial AZFb and -c microdeletion.

Design: Case report.

Setting: Service of Reproductive Medicine, Molecular Biology, CHU Lyon, France.

Patient(s): A case of oligoasthenospermia with partial spermatogenic failure. Screening for Yq microdeletions revealed the absence of sY143, suggesting an AZFb microdeletion.

Intervention(s): Sequence-tagged site mapping indicated that the deletion encompassed a portion of the AZFb and -c region. Genomic DNA from the patient's father gave the same pattern. During the course of these investigations, a pregnancy occurred. On the 46,XY amniocyte and cord blood DNA, the same microdeletion was found.

Main Outcome Measure(s): Study of the fine structure of the Y-chromosome and the gene copy number.

Result(s): The three males of this family have a rearrangement including a deletion encompassing r3 and r4, the palindrome P3, and its boundary regions: u3 and u1 in its distal part. This induced a reduction in DAZ and RBMY1 copy number and complete loss of PRY.

Conclusion(s): PRY is not indispensable to complete spermatogenesis; and with two RBMY1 and two DAZ copies, complete spermatogenesis can be conserved.