Fine mapping of re-arranged Y chromosome in three infertile patients with non-obstructive azoospermia/cryptozoospermia

BACKGROUND: Cytogenetically detectable aberrations of the Y chromosome, such as isodicentrics, rings or translocations are sometimes associated with male non-obstructive infertility. This report presents a detailed analysis of the clinical, cytogenetic and molecular data in three patients with a re-arranged Y chromosome. METHODS: Patients A and B were azoospermic, whereas patient C was cryptozoospermic. All had a somatic mosaic karyotype including a population of 45,X cells and a cell line with a re-arranged Y chromosome. A molecular and FISH analysis of their re-arranged Y was undertaken, which specifically focussed on the presence of the AZFa, b and c regions. RESULTS: The AZFa region was present in all the three patients. The AZFb and AZFc regions were absent in patients A and B, whereas, in patient C, the distal part of AZFb and the whole AZFc region were deleted. Moreover, in this patient, the AZF FISH analysis revealed a mosaicism for the size of the AZF deletion within the re-arranged Y, suggesting a progressive enlargement of the deletion during cell mitotic divisions. CONCLUSIONS: This investigation allowed not only a more precise description of the abnormal Y, but also shed light on how this re-arrangement could be involved in the infertility phenotype.