Microdeletions occurring in the q arm of the Y chromosome may be associated with oligozoospermia or azoospermia. The presence and type of microdeletions may be important to know before performing invasive testicular procedures for in vitro fertilization. The authors are from the Institut Pasteur and University of Florence.


Azoospermia Factors (AZF):

(1) There are 3 non-overlapping regions on the q arm of the Y chromosome termed AZFa, AZFb, AZFc

(2) Microdeletions in one or more of these regions are associated oligozoospermia or azoospermia. A microdeletion in one or more of these regions is found in 15-20% of males with idiopathic azoospermia and 7-10% of men with idiopathic severe oligozoospermia.

(3) Spermatozoa from a patient with a Y chromosome microdeletion are capable of fertilization.


Deletion of AZFa, isolated:

(1) very rare

(2) associated with the Sertoli cell-only syndrome, Type I


Deletion of AZFb, partial:

(1) associated with oligozoospermia

(2) The probability of sperm retrieval by testicular sperm extraction (TESE) is about 50%.


Deletion of AZFb, complete:

(1) The probability of finding mature spermatozoa is virtually 0%.

(2)The presence is a significant adverse prognostic finding for testicular sperm extraction (TESE).

(3) Patients with a complete AZFb should have a diagnostic biopsy. If complete spermatocytic arrest is present, then a TESE procedure is not warranted.


Deletion of AZFc:

(1) This may be associated with hypospermatogenesis or Sertoli cell-only syndrome Type II.

(2) Patients with oligospermia may have a progressive decrease in sperm number with time. Early identification can allow for specimen collection and cryopreservation before sperm counts drop further.

(3) Hidden islands of normal spermatogenesis may be found in patients with Sertoli-only Type II syndrome when multiple biopsies are performed. TESE with cryopreservation may be done in these patients, while intracytoplasmic sperm injection (ICSI) techniques are not recommended.

(4) The probability of sperm retrieval by testicular sperm extraction (TESE) is about 50%.


Multiple deletions (AZFb+c, AZFa+b+c, AZFa+b):

(1) These are associated with a total absence of testicular spermatozoa.

(2)The patient may have a Sertoli-only syndrome or spermatogenic arrest.


Indications for microdeletion testing:

(1) prior to invasive techniques and after demonstration of nonobstructive infertility

(2) young male offspring from a father affected with a Y chromosome microdeletion. If the young man has microdeletion AZFc only, then early collection and cryopreservation of spermatozoa can be performed.


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