What are the Genetic Causes of Male Infertility?
Infertility is the inability of a man to cause pregnancy. This is due to a number of reasons ranging from lifestyle diseases to genetic reasons. Around 10-15% of severe male infertility cases attribute the problem to genetic causes. Chromosomal aberrations and single gene mutations are all genetic causes of male infertility. Transfer of mutations cannot be prevented during natural conception, however, can be overcome by assisted reproduction techniques. Infertility associated with genetics is often due to the production of abnormal sperms or lack of sperm flow.
Genetic Conditions that Affect Fertility
There are a number of chromosomal conditions that lead to lower sperm production:
Men affected by the Kleinfelter syndrome posses an extra X chromosome causing them to have XXY chromosomes in place of XY. One in 1000 men tends to have this fairly common genetic problem. This syndrome results in very low sperm count and testosterone level. Infertility due to this syndrome can be solved with the help of assisted reproductive procedures such as ICSI.
CBAVD (Congenital bilateral absence of the vas deferens)
This is another genetic cause of infertility in men. This mutation is found rarely in people of Caucasian ethnicity and has been proven to affect fertility in men. In such cases, the vas deferens is absent in the reproductive system. This is the tube that carries sperm cells from the testicles to the urethra.
The absence of the vas deferens will cause infertility. If this gene is identified in the male partner, genetic counselling will be recommended to test the presence of cystic fibrosis mutation in the female partner to ensure the safety of the child. This case of infertility can be solved with ICSI in the lab as well.
Y chromosome deletion
Men's fertility can be affected by the absence of the Y chromosome. Deletion of minor data of genetic material from these cells can cause infertility by affecting the sperm cell development. Male offspring of an affected man will have this same mutation and the girl child will remain unaffected as the mutated Y chromosome is not passed on.
Other Chromosomal Abnormalities
Chromosome rearrangements such as balanced translocations can lead to unexplained infertility and repeated miscarriages. Pre-implantation genetic screening can detect abnormal numbers of chromosomes and other genetic diseases which may be present. In such cases, the egg can be fertilised in the laboratory with the sperm and will be genetically tested using PSG to ensure the embryo is mutation-free.