Sperm DNA: What is it and what does it tell me?

 
This past month, I had a few enquiries regarding Sperm DNA or DNA fragmentation. There seems to be some confusion about this fertility parameter, or at least what this parameter can tell us.
 
The object of a sperm cell is to transport the paternal DNA to the egg. As most of you know, in a routine semen analysis we test for sperm count, the motility, the volume of cells in a sample, the pH and a few other parameters. Basically, it is an indicator of the number of cells that are being produced and their ability to swim to the egg. However, as you may have spotted, there is no test for the all-important DNA package in the sperm cells.
 
Imagine a delivery van coming to your home with a parcel. Imagine the delivery van arrives at the front door, there is a knock on the door and when you open it - the delivery man has forgotten the package, or the package arrives so damaged, that it is not usable anymore. This is the point of a Sperm DNA test. If a man is producing a high number of sperm cells, their motility is good and their form is strong, this would elude us to think that the cell itself is strong. This may or may not be the case, and it is particularly important for couples undergoing assisted reproduction.
 
 
The embryo-to-be is made up of maternal and paternal DNA. It is of critical importance that the DNA package in the sperm cell is strong and healthy to support a viable embryo and pregnancy.
 
It appears that sperm quality is declining and this is thus contributing to the increasing rates of infertility throughout the world. Many factors have been implicated (smoking, dietary deficiencies, environmental pollutants, cancer therapy) and it is thought that the problem is related to free radicals. Free Radicals (apart from being a terrible name) are small particles in the body that basically cause cellular damage - in this case, they damage the DNA of the sperm. A certain degree of damage (fragmentation) to the DNA of the sperm is inherent, but the woman’s eggs can repair some of the damage. This is especially true if the eggs are also healthier but as a woman gets older; the ability of her eggs to repair the damaged DNA in the sperm is reduced.
 
A higher rate of sperm DNA fragmentation, can impact on:
 
• fertilisation, both natural and assisted reproduction
• embryo quality
• pregnancy rates
• and even miscarriage
 
 
Recent studies report that these tests show great promise for improving the diagnosis of male infertility. It can also be a good indicator of success with intrauterine insemination (IUI) and in vitro fertilization (IVF).
 
In 50% of involuntarily childless men, the sperm DNA is fragile and fertility is reduced. This problem is only revealed by an examination of DNA quality. With a routine sperm examination, most men will be given the fertility “all-clear”. This means that all the focus is then shifted onto the woman.
 
From the most recent review into DNA damage in sperm cells:
"The large body of literature informs those working in human fertility of the importance of assessing DNA damage in human spermatozoa, in terms of effectiveness of treatment and the health of offspring conceived using this technology (Assisted Reproductive Technologies). It is an important element of semen quality: useful in the diagnostic workup of the male and also as an additional indicator of assisted reproduction treatment success."
Déanta in Éirinn - Sheology
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