Genetic Testing for Infertility: Diagnosing Rare Genetic Disorders

Genes which are the make-up of DNA are a very essential part of hereditary. Genes come in pairs, one part from the male parent and the other from the female parent. Also, genes are the dominant elements in DNA that determine an individual’s development, function, and their attributes like hair color, height, and even eye color. A genetic disorder happens when genes are not properly formed. This occurs either before birth or through a mutation after birth. Genetic disorders may happen due to problems with either genes or chromosomes. These disorders can affect fertility in the following ways:

• They can cause individual infertility in either males or females by affecting their reproductive systems.
• An inherited single gene disorder by an embryo can result in miscarriage or an implantation failure.
• A chromosomal abnormality in the embryo can also lead to a failure of implantation or a miscarriage after the implantation.
• Genomic imprinting can lead to chemical changes in the DNA that when combined with a mutation can lead to a miscarriage or diseases in the resulting child.

Also, a child that is born with a single gene disorder or a chromosomal abnormality may not survive after birth, and even when they do will have developmental abnormalities or congenital defects depending on the abnormality. Fertility specialists endeavor to prevent the occurrence of these gene disorders through evaluation prior to conception, or through preimplantation genetic testing after conception through in vitro fertilization. Chromosomal problems cause more cases of infertility or pregnancy issues than do single gene disorders. Another type of genetic disorder called genomic imprinting is due to abnormal chemical modification of parts of the DNA that make up specific genes. This can result in changed proteins that may either cause miscarriage or a disease in the baby.

What are the Types of Genetic Testing for Infertility in Males?

Male infertility genetic tests look for chromosomal or genetic abnormalities. In general, a genetic test usually detects no abnormality in men, but about 15% of men with low sperm count or azoospermia, test positive for a genetic disorder. There are many types of genetic tests for infertility in males; there are three common types of tests. They include:

Karyotype 

This test is essentially a picture of the chromosome. A cytogeneticist stains the chromosome and visualizes it under a microscope. The picture is then cut up, rearranged by chromosome size, and examined for missing or extra pieces. The test analyses blood chromosomes which are referred to as karyotypes. It tests for the overall setup of the chromosomes. It can detect the presence of either an extra or a missing chromosome, and whether the chromosome is missing large pieces or has extra sections of genetic code.

Cystic fibrosis gene mutation testing 

This test looks for mutations in cystic fibrosis gees that can cause infertility in men. The cells used for these tests are obtained from a blood draw or through gentle scraping from the mouth. They contain the man’s DNA, which is analyzed by the lab. Males with an absence of the vas deferens (CAVD) have at least one mutation that can cause cystic fibrosis. These men and their female partners should undergo genetic testing for cystic fibrosis genes to ensure they do not pass the genes to their offspring.

Y chromosome microdeletion test 

This examination looks for any genetic information that is lacking from the Y chromosome and is essential for the normal generation of sperm. Y chromosome microdeletion is not visible enough to be detected by a normal karyotype test. Genetic labs make use of polymerase chain reaction methods to analyze sites on the length of the Y chromosome. The AZF region contains the majority of deletions that result in reduced or no sperm production. The exact location can also indicate the particular treatment that will be recommended by the fertility specialist. The test may be carried out before performing intra-cytoplasmic sperm injection in males with azoospermia or very low sperm count. Apart from infertility, no other health risks are indicated by microdeletions in the Y chromosome. Also, a negative result on the test does not fully guarantee that a genetic abnormality is not present.

Genetic Tests for Infertility in Females

Many women are unable to conceive and deliver a healthy baby because of genetic factors. In some cases, it is due to inherited chromosome abnormalities. Other times, it may be due to an inherited single-gene defect. Also, if the other women in the family have had issues conceiving due to premature menopause, endometriosis, or other factors, the woman may be at an increased risk of getting the same issues. 

One of the major tests done is embryo testing, which is done in synchronization with in vitro fertilization. This test is done after the egg is fertilized and grown in the lab for a few days. When the embryo is at the 6-8 day stage, a single cell is biopsied from the embryo and subjected to preimplantation genetic testing. 

This preimplantation genetic testing comprises preimplantation genetic diagnosis and preimplantation genetic screening. It is also recommended that the fetus undergoes other common methods of prenatal testing after pregnancy like chorionic villus sampling and amniocentesis. This is because there is a known error rate for preimplantation genetic testing and combining it with prenatal testing can eliminate the risk of misdiagnosis. 

Preimplantation genetic testing is crucial for every pregnancy, especially when trying to prevent some hereditary diseases that are carried in the genes. Most times, these tests are available with overseas medical treatment, hence the need for a trusted meditour agency. 

Aneuploidy Screening 

This screening checks for any specific set of chromosomes that contribute to recurrent miscarriages to ensure that they are normal. This can be done during PGD and PGS. This is especially helpful when using IVF or surrogacy. It will help detect the source of the problem and prevent wasting of resources. 

The most commonly occurring chromosomal abnormalities that are related to pregnancy loss are:

• Trisomy
• Monosomy
• Triploidy
• Sex chromosome abnormalities

This test is carried out as with embryo genetic testing. The ovaries are stimulated, the eggs are harvested and fertilized, the embryo is grown for some time in the lab, and an embryonic cell is removed and examined. The cell removed from each embryo is tested for some chromosomes or a specific chromosomal disorder. Only the normal testing embryos are transferred into the uterus for implantation, increasing the chances of a healthy pregnancy.