Multiplex PCR Kit for Determining AZF Deletion Boundaries and gr/gr Deletions | Devyser AZF ⁠Extension

The AZF Extension kit answers the question that the step 1 screening kit cannot: where the deletion starts and ends. This distinction is not purely academic; it directly changes clinical counseling, because two deletion types that give the same screening pattern can have different prognoses.

The clearest example is distinguishing a complete AZFb deletion from an AZFbc deletion. Both cause loss of the AZFb marker signals at the screening step, but the chances of sperm retrieval by micro-TESE differ. Similarly, a terminal Y chromosome deletion (with loss of the Yq12 heterochromatic region) may look like an AZFc deletion on the basic marker set, while its genetic nature and the risk of Y chromosome instability in the next generation are different. Marker sY160 in the Extension kit is precisely the marker that distinguishes these two situations.

The second benefit is the detection of gr/gr partial deletions, a type of small deletion within the AZFc region that the basic screening kit does not assess at all. The EAA/EMQN 2023 guidelines identify gr/gr as a population-specific risk factor for impaired spermatogenesis, as well as a predisposing factor for testicular germ cell tumors. The clinical significance of this finding goes beyond reproduction: carriers of gr/gr have reason to undergo regular testicular monitoring. The guidelines leave gr/gr testing to the discretion of the laboratory and the referring physician rather than making it mandatory - this point must be stated correctly during counseling, avoiding presenting it as a mandatory requirement.