Y chromosome microdeletions (AZF)
The integrity of the Y chromosome is important for the production of spermatozoa. In some cases small parts of the Y chromosome are missing and the genes that give the information to the testes for spermatozoa production are lacking having as a result serious male infertility problems. The test for the detection of the Y chromosome microdeletions is also called “AZF” from the initials of the words “azoospermia factor”.
There are three regions of the Y chromosome that may be missing, AZFα, AZFb and AZFc.
- Men with microdeletions at the AZFa or AZFb locus always have azoospermia – a condition in which there are no spermatozoa in the semen sample. According to the literature,
~ 10-15% of men with azoospermia have this deficiency.
In cases where there are no spermatozoa in the semen sample, the man will undergo a biopsy to retrieve spermatozoa from the testes. The AZF test must be done before the biopsy because, if an AZFa or an AZFb deletion is detected, the literature has shown that no sperm will be found in the testicular tissue, so there is no reason for the men to undergo surgery.
- Men with AZFc microdeletion can have spermatozoa in their semen sample. However the concentration is <5 million/ml (oligozoospermia). AZFc microdeletion occurs in 6% of men with low sperm quality. The sperm count in men with AZFc is low but it does not rule out natural conception but even in this case the AZF will be transferred to the male embryos.
It is absolutely necessary for men with AZFc deletion to cryopreserve their semen sample. Studies have shown that, over time, sperm production will stop in this category of men. Therefore it is important that these men visit a Sperm Bank in order to save their biological material for future use.
FISH on sperm