What are the genetic causes of male infertility?
Male infertility can be caused by low sperm production, abnormal sperm function or blockages that prevent the delivery of sperm. Illnesses, injuries, chronic health problems, lifestyle choices and other factors may contribute to male infertility. In some cases, the causes of infertility may not be any of the aforementioned ones, instead, they could be genetically inherited. Some of these include – Klinefelter’s syndrome, cystic fibrosis and Kallmann’s syndrome, amongst others.
Klinefelter Syndrome
Klinefelter’s syndrome is a male pattern infertility condition wherein a male is born with two X chromosomes and one Y chromosome instead of one X and one Y chromosome. This leads to the abnormal development of the male reproductive organs. The condition is typically diagnosed around adolescence. Those suffering from the condition are also known to have enlarged breasts syndrome, called gynecomastia.
Cystic fibrosis gene mutation
Cystic fibrosis is a genetically inherited, life-threatening disorder that affects the lungs and the digestive tract. The abnormalities in the cystic fibrosis genes – known as the cystic fibrosis transmembrane conductance regulator are also associated with the absence of the vas deferens causing blockage of the ejaculatory duct or blockage of the epididymis.
Y chromosome microdeletions
Y chromosome infertility is a condition that affects the production of sperm and causes male infertility. This condition makes it difficult for the man to produce mature sperm cells, which leads to a reduction in the number of sperm cells in the seminal fluid, or sperm cells that are abnormally shaped or that do not move properly. Men with Y chromosome infertility do not have any other signs or symptoms related to the condition.
Chromosomal Translocation
Chromosomal abnormality is a genetic disorder wherein a chromosome breaks and a portion of it reattaches to a different chromosome. Chromosomal translocations can be detected by analysing karyotypes of the affected cells. These Chromosomal translocations are typically seen in cases of leukaemia but also associated with infertility conditions. The chromosomal translocations do not appear to affect semen volume, but translocations appear to be lower than in fertile men.
Noonan Syndrome
Noonan syndrome is a genetic disorder that prevents normal development in various parts of the body. The effects of Noonan syndrome can be exhibited in a wide variety of ways and includes abnormal facial characteristics, short stature, heart defects, other physical problems and possible developmental delays. One of the manifestations of the condition in men would be undescended testicles that cause infertility.
What are the types of genetic testing for infertility in men?
Karyotyping
A karyotype genetic test ascertains the size, shape, and number of chromosomes – which should be a pair of 23 or 46 chromosomes in all. This test helps confirm or diagnose a genetic disorder or disease and help ascertain if a couple is at risk of having a child with a genetic or chromosomal disorder. The test is prescribed in case you’ve been unable to conceive naturally for a year, or have had multiple miscarriages, or have experienced a stillborn birth.
Cystic fibrosis gene mutation testing
Cystic fibrosis genetic testing looks to ascertain if the cystic fibrosis genes can cause infertility in men. This is ascertained by checking the cells from a blood sample drawn containing the man’s DNA and analysed for congenital absence of the vas deferens (CAVD). Most men with CAVD have at least one mutation that can cause cystic fibrosis. These men and those who produce no sperm, along with their female partners, should undergo genetic testing for cystic fibrosis genes to make sure an offspring would not inherit the disease.
Y chromosome microdeletion test
Y chromosome microdeletion is diagnosed by extracting DNA from leukocytes in a man’s blood sample. It also aids in determining the cause of azoospermia or oligospermia and helps predict the effectiveness of assisted reproductive technologies in men with Y chromosome microdeletions.
