Frequently Asked Questions
Diagnosing infertility of genetic causes is a complex procedure as numerous genes are involved in the various aspects of male fertility. If the semen analysis shows that the man has low sperm count, absence of sperms, or physical abnormalities like small testicles, genetic screening may be advised.
- Klinefelter syndrome
In Klinefelter syndrome, the man has an additional X chromosome. This renders almost all men with it infertile. This genetic abnormality is usually diagnosed before or at birth. In adolescents or adults, it is diagnosed in men who have small testicles or have hypogonadotropic hypogonadism. Men who have enlarged breasts also may have this syndrome. In addition, these men may have reduced pubic and facial hair, low sex drive and a small penis.
- Cystic fibrosis gene mutation
Cystic fibrosis is a disorder that is inherited and can be fatal. It mainly affects the digestive tract and the lungs but a specific mutation can also affect male fertility. The abnormality is called cystic fibrosis transmembrane conductance regulator or CFTR. IT is associated with an absent vas deferens. Those with CFTR may not have cystic fibrosis themselves but may act as a carrier of the gene. Those with CFTR are rendered infertile due to the bilateral absence of the vas deference but can have a biological child if the sperm is extracted from the testicles and used in IVF.
- Y chromosome microdeletions
Y chromosome microdeletions can affect sperm production adversely. it affects the genetic script required to produce healthy sperms to be aberrant. Almost 16% of men with severe oligospermia and azoospermia suffer from Y chromosome microdeletions. Genetic counselling is important when a man with this genetic problem and his partner decides to have a child. If they have a son, he will inherit this genetic abnormality and will be infertile too.
- Chromosomal translocation
An unusual rearrangement of chromosomes is known as chromosomal translocation. There are two main types of these translocations known as reciprocal translocation and Robertsonian translocation. Men who have these problems can have varying degrees of low sperm count or may not have sperm in their semen.
- Noonan syndrome
When there is mutation in over eight genes, the condition is known as Noonan syndrome. It is generally noticed at birth, and the physical presentation can vary in different people. The abnormalities may be present in structures like elbows, head, face, sternum and spine. They may have blood disorders, heart problems and intellectual problems too. Men with Noonan syndrome may have infertility too. In many cases, one or both of the testicles fail to drop into the scrotum. The condition can be corrected surgically and mature sperm may develop following the treatment. Men who did not have undescended testicles may also have some fertility problems.
Genetic tests are prescribed in men who have infertility to identify chromosomal genetic abnormality. There are over 1000 kinds of genetic tests, but three of them are most commonly used to determine male infertility.
A karyotype is a picture of the tested chromosome. The test works through the various blood chromosomes or karyotypes and a cytogeneticist looks for the positioning and the number of chromosomes. The test will find out if there are copies of the chromosomes or if there are missing chromosomes. Sometimes large pieces of the genetic code may be missing, or there may be an extra section of the genetic code.
- Cystic fibrosis gene mutation testing
Cystic fibrosis gene mutation testing is used to find out mutations of the cystic fibrosis genes. In most men with the congenital absence of vas deferens, there is a minimum of one mutation present. The men with this genetic abnormality and their partners must go for genetic counselling to ensure that this is not passed on to a future child.
- Y chromosome microdeletion test
The Y chromosome microdeletion test looks for missing genetic information in the Y chromosome. These microdeletions may not be big enough for a general karyotype test to recognize. The polymerase chain reaction method is used to test the Y chromosome. The AZF region is the one that contains most deletions that produce no sperms or very low levels of sperm. A negative test result on Y chromosome microdeletion test may not mean that the abnormality is absent.