Clinical relevance of Y-linked CNV screening in male infertility: new insights based on the 8-year experience of a diagnostic genetic laboratory.

AZF microdeletion screening is routinely performed in the diagnostic work-up for male infertility; however, some issues remain debated. In this study, we provide insights into the sperm concentration cutoff value for routine testing, the predictive value of AZFc deletion for testicular sperm retrieval and the Y-background contribution to the interpopulation variability of deletion frequencies. In the Spanish population, partial AZFc rearrangements have been poorly explored and no data exist on partial duplications. In our study, 27/806 (3.3%) patients carried complete AZF deletions. All were azoo/cryptozoospermic, except for one whose sperm concentration was 2 × 10(6)/ml. In AZFc-deleted men, we observed a lower sperm recovery rate upon conventional TESE (9.1%) compared with the literature (60-80% with microTESE). Haplogroup E was the most represented among non-Spanish and hgr P among Spanish AZF deletion carriers. The analysis of AZFc partial rearrangements included 330 idiopathic infertile patients and 385 controls of Spanish origin. Gr/gr deletion, but not AZFc partial duplications, was significantly associated with spermatogenic impairment. Our data integrated with the literature suggest that: (1) routine AZF microdeletion testing could eventually include only men with ≤2 × 10(6)/ml; (2) classical TESE is associated with low sperm recovery rate in azoospermic AZFc-deleted men, and therefore microTESE should be preferred; (3) Y background could partially explain the differences in deletion frequencies among populations. Finally, our data on gr/gr deletion further support the inclusion of this genetic test in the work-up of infertile men, whereas partial AZFc duplications do not represent a risk for spermatogenic failure in the Spanish population.