Study of microdeletions on the Y chromosome
Study of microdeletions in the AZFa, AZFb and AZFc regions of the Y chromosome leading to different patterns of male infertility, from severe oligospermia to non-obstructive azoospermia.
What are Y chromosome microdeletions?
Y-chromosome microdeletions are losses of small fragments of the Y-chromosome. These losses have a negative impact on male fertility, as spermatogenesis (sperm production) is affected.
The Y chromosome is the sex chromosome of males. It is characterised by being the smallest chromosome and contains a number of male-specific genes.
Microdeletions of the Y chromosome generally cause from a low quantity of sperm in the ejaculate (oligozoospermia) to the total absence of sperm in the ejaculate (azoospermia). It is therefore advisable to carry out a genetic study of microdeletions in patients with a normal karyotype but with one of these seminal alterations.
When a male presents any alteration, damage or loss of a fragment of this chromosomal region, he will be diagnosed with a male factor that causes infertility.
The Y chromosome is composed of two arms (the short arm, Yp, and the long arm, Yq) and a centromere. When using the deletion mapping technique, it is divided into seven deletion intervals, which are further subdivided into sub-intervals designated by letters of the alphabet. The short arm contains intervals 1 to 4, and the long arm contains intervals 5 to 7.
Study of microdeletions on the Y chromosome
At Genosalut we analyse by qPCR-melting the microdeletions of the Y chromosome: AZFa, AZFb and AZFc.
qPCR amplification of the regions of interest with specific primers and subsequent melting analysis:
- AZFa region: markers sY84 and sY86
- AZFb region: markers sY127 and sY134
- AZFc region: markers sY254 and sY255 (both in the DAZ gene)
Our value proposal
When it is recommended to test for Y chromosome microdeletions?
This test is recommended in patients with alterations in the number of spermatozoa in the seminogram, mainly:
- In oligospermic patients (less than 5 million/ml sperm count).
- In azoospermic patients (absence of spermatozoa in the ejaculate).
Information from the study of Y chromosome microdeletions
How can I request a Y chromosome microdeletion study?
The study of microdeletions of the Y chromosome allows the loss of fragments in the Y chromosome that contain genes necessary for the production of spermatozoa to be verified.
The Y chromosome is the sex chromosome of males and contains specific genes necessary for proper sexual differentiation and sperm formation.
In patients with fertility problems and low sperm count (oligozoospermia) or absence of sperm (azoospermia), the study is used to examine the integrity of the Y chromosome. It is estimated that 10% of males with seminogram alterations have losses of small fragments of the Y chromosome (microdeletions) in regions known as AZFa, AZFb and AZFc.
Identifying whether a male has these alterations not only helps to establish the possible cause of fertility problems but also to offer appropriate genetic counselling.
To perform this study, a blood or saliva sample is needed to extract the patient’s DNA.
Subsequently, the areas of interest (AZFa, AZFb and AZFc) are amplified using the real-time PCR technique (qPCR). The presence of all regions indicates that the patient does not have any alteration. The absence of any region implies that the patient is a carrier of microdeletions on the Y chromosome.
The possible results are:
- No microdeletions are detected on the Y chromosome: In such a case the cause of the infertility problems has to be another one.
- Microdeletions are detected in the Y chromosome: In this case it is important to know the deletion region or regions (AZFa, AZFb or AZfc) as the severity of the sperm production defects depends on this, and finally determines the reproductive alternatives available. In other words, the possibility of finding healthy spermatozoa in the ejaculate or testes and therefore of obtaining biological offspring.
As mentioned above, a genetic counselling session is recommended to clarify any doubts and explain the possible reproductive alternatives in each case.
In addition, it may be advisable to carry out the study on male siblings to find out if they are also carriers and will therefore suffer fertility problems.
On the other hand, all male children of patients with microdeletions of the Y chromosome will inherit this alteration.
The study of microdeletions of the Y chromosome is covered by some private insurance companies and sometimes depends on the fulfilment of certain diagnostic criteria (oligospermia, azoospermia…). You can come to us with a certificate from your doctor or with your insurance card.
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