DNA Damage And Sperm
While the majority of cases of male infertility can be attributed to poor sperm quality - comprised of sperm count, sperm motility, and sperm shape or morphology - in other instances the causes are unknown. Sperm dysfunctions can be the result of a combination of factors, among them DNA damage or genetic defects.
The DNA-Sperm Connection
Genes are made of DNA, or chains of molecules that carry the genetic material of each human being. In males, half of the genetic information or DNA of a newborn is carried in the sperm. When sperm are damaged by having fragmented or broken DNA chains, they are less able to fertilize an egg in order for a couple to become pregnant.
Mature, healthy sperm consist of a head containing a man's DNA or genetic material, and a tail the moves back and forth speedily in order to propel the sperm forward, or to "swim." This ability to progress with speed and strength, as well as to move in a straight line, is a critical aspect of male fertility. Without it, the ability to conceive is severely impaired.
Further, research suggests that up to 10% of male infertility problems are the result of genetic or DNA abnormalities in the sperm head, or more specifically in the arosome. The arosome is the membrane cap on the sperm that is filled with enzymes, and which is crucial for penetrating an egg. Hence DNA damage can have severe repercussions on the ability of sperm to function as they should.
Sperm and Genetic Disorders
It is believed that even men with no known fertility problems may suffer from a certain degree of genetically defective or DNA-damaged genes. These DNA defects can be the result of environmental hazards, such as radiation exposure, or they can be inherited. There are certain inherited genetic disorders that are known to impair fertility in men. Here are a few examples of such disorders and how damaged DNA can impair sperm and male fertility.
Cystic Fibrosis: The tubes that carry the sperm are missing or blocked
Klinefelter Syndrome: DNA is comprised of two X chromosomes and one Y chromosome, instead of the normal one X chromosome and one Y chromosome. This condition can lead to destruction of the lining of tubes in the testicles during puberty. .
Kartagener Syndrome: In this rare genetic disorder, defined by reversed positions of major organs, sperm motility can be impaired.
Polycystic Kidney Disease: Large cysts form on the kidneys and other organs. If cysts develop in the reproductive track, this condition can lead to infertility.
During sexual intercourse, genetically impaired sperm are unlikely to reach and fertilize an egg. However, when assisted reproduction or fertilization techniques are used, there is the added concern that genetic abnormalities will be passed onto the offspring. Furthermore, DNA-damaged sperm can have the adverse consequences of fertilization failure, stillbirth, miscarriage, and inherited infertility.
DNA Testing Through Genetic Analysis
DNA testing by means of genetic analysis is recommended when there is a suspicion that either the man or the woman is infertile. Counseling is also advised for a couple when genetic abnormalities are suspected.
For men, a genetic analysis can help identify DNA fragmentation in sperm, chromosomal defects, or genetic diseases. In fact, some studies suggest this type of DNA testing may be a superior method of predicting whether or not conception can occur than the more standard semen analysis procedure.