AZFb microdeletions and oligozoospermia—which mechanisms?

Atypical deletion patterns are presented in two oligozoospermic males. The Y chromosome with highly repetitive block sequences in AZFb and AZFc led to deletions by intrachromosomal recombination mechanisms (28w).

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Ana Rita Soares, M.D., Paula Costa, M.Sc., Joaquina Silva, M.D., Mário Sousa, M.D., Ph.D., Alberto Barros, M.D., Ph.D., Susana Fernandes, Ph.D.

Volume 97, Issue 4, Pages 858-863



To characterize the deletion patterns and its breakpoints in oligozoospermic patients presenting AZFb and AZFc microdeletions and to understand the recombination mechanisms underlying these microdeletions.


Case report.


Genetics Department of Faculty of Medicine of Porto, Porto, Portugal.


Two men with severe oligozoospermia and two men with nonobstructive azoospermia identified as having different AZFb+c deletion patterns via Y chromosome microdeletion analysis.


Definition of microdeletions and the fine characterization of the respective breakpoints by sequence-tagged sites (STS) polymerase chain reaction (PCR) and single-nucleotide variant (SNV) PCR.

Main Outcome Measure(s):

Study of the fine structure of the Y-chromosome and discussion of the putative mechanisms involved in each microdeletion pattern.


From the four patients studied, three deletion patterns were identified: IR4/distal-P2 (25%; 1 of 4), P5/proximal-P1 (50%; 2 of 4), and P5/distal-P1 (25%; 1 of 4). Although severe oligozoospermia is normally associated with AZFc, a complete AZFb deletion was found in one case.


Analysis of these patients has revealed a new putative region that may be involved in spermatogenesis conservation.

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