Is Sperm DNA Fragmentation really important in Male Infertility?


Is Sperm DNA Fragmentation really important in Male Infertility?

The simple answer to the above question is yes. In this article we outline the basics of Sperm DNA Fragmentation, it’s role in Male Infertility and the various testing methods.
Did you know, even healthy sperm may have some DNA damage but it’s the amount of damage present that matters.

Sperm DNA Fragmentation replaces the Male Infertility test – Semen Analysis?

While the Semen Analysis still remains the first and most common test done for evaluating the male fertility potential, it has certain limitations such as only evaluating the physical characteristics of the sperm like volume, pH, concentration, size and shape of the sperm (Morphology) and the ability of the sperm to move towards an egg (Motility of the sperm) and the presence of antibodies. It does not give us any information about the inside of the sperm nor does it reveal any problems that could be there with the genetic material or DNA of the sperm.
A Sperm DNA Fragmentation (SDF) Test analyses the genetic content inside the sperm and reports on levels of DNA damage which could be one of the overlooked causes contributing to Male Infertility.  Poor Sperm DNA integrity can lead to male subfertility, failure to conceive or failure in the assisted reproduction treatment (ART). The genetic integrity of the sperm (Sperm DNA) is crucial for successful fertilization and normal embryo development, leading to a successful pregnancy.
Sperm DNA Fragmentation refers to single and double stranded breaks in the DNA strand inside the sperm head. DNA Fragmentation may inhibit the activation of paternal gene expression at 4 cell stage of embryo development.

Causes of Sperm DNA Fragmentation

In men, the major contributory factor for sperm DNA damage is Oxidative Stress. Oxidative stress results from an imbalance between high levels of reactive oxygen species (ROS) and not enough scavenging antioxidants being produced by the body.
Oxidative stress can occur due to a range of various causes, most notably, infections like Pyrexia, Leukocytospermia, genetic disorders, stress, cigarette smoking, alcohol, drug abuse, advancing age, exposure to harmful substances or pollution in the working environment. The other factors contributing to Sperm DNA Fragmentation could include the presence of a varicocele and other occupational or lifestyle factors leading to elevated testicular temperature, stress, poor/unhealthy diet.

Who should have a Sperm DNA Fragmentation Test?

Routine testing for Sperm DNA Fragmentation is not recommended, however there are certain indications for patients, in which sperm DNA fragmentation testing is recommended.
Since advancing male age has an effect on the Sperm DNA quality, men above 40-45 years who have trouble conceiving are advised to undergo a sperm DNA fragmentation test. Couples who are considering fertility treatments can also have a Sperm DNA Fragmentation test to check the quality of their Sperm DNA and then decide on the most beneficial treatment to be taken. Couples with unexplained infertility or those who have had previous failed fertility treatments can also get some answers by getting their Sperm DNA tested. Other indications include cases of recurrent miscarriages and early pregnancy losses, presence of a varicocele, exposure to harmful substances (fertilizers, pesticides, radiation, high temperatures, chemicals). Studies have also shown that previous episodes of high fever, urinary infections, mumps and TB can also lead to high levels of Sperm DNA fragmentation.

Types of Sperm DNA Fragmentation tests

There are many different methods to test for Sperm DNA fragmentation and each have their own advantages and disadvantages. The most common tests available are the SCSA® Test, TUNEL assay, the COMET assay and the SCD test.
The SCSA® Test and TUNEL assay are more robust as they use an instrument called a flow cytometer to analyse the Sperm DNA Fragmentation and can analyse a large number of cells giving a more accurate representation of the overall Sperm DNA integrity of the sample.
The COMET and SCD tests are microscope based methods and are subject to high levels of variation due to operator dependency.
The sperm DNA damage is expressed in terms of DFI (DNA Fragmentation Index) indicates the impaired fertility potential and the immature sperm chromatin is expressed as HDS (High DNA stainability).

Healthy Sperm? Look Closer…

Sperm DNA Fragmentation testing is gaining importance in Male Infertility evaluation. Studies have shown that levels of Sperm DNA fragmentation correlate with the success of specific ART and fertility treatments. Hence doing a Sperm DNA Fragmentation test could help in better clinical and treatment management and reduce the emotional and financial burden that a couple has to undergo. Sperm DNA Fragmentation tests can provide answers to patients on previous failed fertility treatments and also help guide patients on the most successful treatment option to be undertaken.
It is extremely important to choose the right test and reliable laboratory to provide accurate results on the Sperm DNA integrity of the sample as only genuine reports can help the clinician and the patient.

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