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Evaluating men with azoospermia, severe oligozoospermia, or
otherwise unexplained male factor infertility
Yq microdeletions involving some or all of the AZF gene are the most
frequently identified cause of spermatogenic failure in chromosomally
normal men with nonobstructive azoospermia (8.3%) or severe
oligospermia (5.5%). Among unselected infertile males, the overall
frequency of Yq microdeletions is 3%. The relative frequency of Yq
microdeletions make the evaluation for them an important aspect of the
diagnostic work up in infertile males, especially those with
spermatogenic failure (sperm density <5 million/ml).
Most cases of Yq microdeletions occur de novo, and due to the
consequential infertile phenotype, they are typically not transmitted.
However, in cases where assisted reproductive technology (example:
TESE followed by ICSI) is used to achieve viable pregnancy, all male
offspring born to a microdeletion carrier will carry the deletion and may
be infertile.
Men testing positive for 1 or more microdeletions who are enrolled in
an in vitro fertilization (IVF) treatment program may wish to consider
alternative options to intracytoplasmic sperm injection (e.g., donor
sperm) and consultation with an experienced reproductive
endocrinologist and medical geneticist is recommended.
Most Y microdeletions are the result of homologous recombination
between repeated sequence blocks. Testing for deletions involves
investigating for the presence or absence of markers located within
non-polymorphic regions of the AZF gene.
Abnormal: the presence of 1 or more deletions in specific regions
of the Y chromosome (designated AZFa, AZFb, and AZFc)
Normal: the absence of deletions in the regions of the Y chromosome
under test
An interpretative report will indicate whether or not results are consistent
with a diagnosis of Y chromosome microdeletion.
Y chromosomal microdeletions may be the cause of the defects in
spermatogenesis observed in some infertile men.
The particular markers used in this assay are expected to detect greater
than 95% of the deletions in the 3 AZF regions.(1)
A positive result (presence of a deletion) does not necessarily mean
that this is the cause of the infertility or azoospermia in this patient.
A negative result (absence of microdeletions) does not
rule out the presence of other genetic or nongenetic factors that may
be the cause of infertility or azoospermia.
Microdeletions not detected by the markers used in this assay may be
present.
The absence of a deletion in DNA from peripheral blood does
not necessarily rule out the presence of a deletion in the germline DNA
(sperm).
The laboratory maintains quality control and quality assurance programs
to ensure a high quality of testing. Nevertheless, rare errors may occur,
for example, due to specimen mix-ups (within the laboratory or prior to
receipt by the laboratory) or due to technical errors.
Test results should be interpreted in the context of clinical findings,
family history, and other laboratory data. Errors in our interpretation of
results may occur if information given to us is inaccurate or incomplete.
A genetic consultation is recommended for all patients undergoing this
testing. Additional consultation with a reproductive endocrinologist/
urologist to discuss reproductive options is recommended when a
deletion is detected.
1. Simoni M, Bakker E, Eurlings MC, Matthijs G, et al: Laboratory
guidelines for molecular diagnosis of Y-chromosomal microdeletions.
Int J Androl 1999 Oct;22(5):292-211
2. Pryor JL, Kent-First M, Muallem A, van Bergen AH, et al: Microdeletions
in the Y chromosome of infertile men. N Engl J Med 1997 Feb 20;336(8):
534-539
3. Kent-First MG, Kol S, Muallem A, et al: The incidence and possible
relevance of Y-linked microdeletions in babies born after
intracytoplasmic sperm injection and their infertile fathers. Mol Hum
Reprod 1996 Dec;2(12):943-950
4. Shalender Bhasin: Approach to the Infertile Man. Journ of Clin Endo
& Metab 2007 June 92(6):1995-2004.
5. Ferlin A, Arredi B, Speltra E, et al: Molecular and Clinical
Characterization of Y Chromosome Microdeletions in Infertile Men: A
10-Year Experience in Italy. Journ of Clin Endo and Metab. 2007
Mar 92(3):762-770