Y chromosome - (regions AZFs, AZFb, AZFc)

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Eurofins Biomnis code

DELY

Synonyms
  • DAZ gene - deleted in azoospermia
  • Microdeletions in the Yq11 region, azoospermia factor (AZF)
Specialty

Genetics

Clinical significance

Male sterility induced by Y chromosome deletion is characterised by severe spermatogeny disorders. Y chromosome deletions represent a frequent genetic cause of male infertility. Their prevalence is estimated at 1:2500. Transmission is linked with the Y, with incomplete penetrance, but as deletions are frequently associated with infertility, they are generally produced de novo. 5% to 10% cases of secretory azoospermia (complete lack of spermatozoa) or severe oligozoospermia (<1 million spermatazoa/ml) in men are associated with microdeletions in the euchromatic part of the long arm of the Y chromosome, at the AZF (Azoospermia Factor) locus. There are several distinct subregions at the AZF locus. The structure of the Y chromosome in this region rich in repeated palindromes and recombination phenomena between 2 flanking sequences with a very high level of homology are the source of various deletions: i) AZFa deletions, the rarest ii) AZFb or P5/proximal-P1 deletions, iii) AZFb+c deletions, with a distinction made between two types: P5/distal-P1 or P4/distal-P1 and iv) AZFc deletions due to recombinations between the b2 and b4 palindromes. AZFc deletions are the most frequent and are associated with azospermia or generally severe oligozoospermia. Complete AZFa, AZFb+c and AZFb region deletions are always associated with azoospermia, the testicular histology demonstrating a complete absence of germinal line cells (SCOS or Sertoli cell only syndrome) or more or less systematic arrested matuation of spermatogenetic line cells. The diagnosis is suggested in men displaying azoospermia or oligozoospermia, in otherwise good health, after ruling out other causes of infertility; a number of men displaying severe oligospermia may have children without fertility treatment. The severity of the infertility varies according to the AZF region concerned by the deletion: complete deletion of the AZFb region is associated with more severe infertility than AZFc region deletion. Detecting microdeletions in these regions makes it possible to evaluate the chances of success of ICSI, by specifying the probability of detecting mature germinal cells by means TESE ("Testicular Sperm Extraction") in testicular tissue. Complete deletion fo the AFZb region is thus a negative prognostic factor. On the other hand, in the case of AZFc deletion, the chances of detecting spermatozoa in testicular tissue are in the region of 50%.

Preanalytics
  • A tube specifically for this analysis : No
Further information

According to regulation, each request must ALWAYS be accompanied by a consent form signed by the patient and the prescribing pathologist
Sample must be refrigerated if transport is > 48 hours
Enclose the specific B12-INTGB request form: Molecular Genetics

Documents to download
Methodology

Multiplex PCR

Turnaround time

9 days

Testing Laboratory

Contact(s)
Customer Care