Some genetic conditions may affect fertility or may be treated by variation in in vitro fertilization (IVF). In general, these genetic abnormalities fall into two categories: single gene defects and chromosomal abnormalities.
Defects in a single gene involve a mutation or abnormality in the DNA that encodes a particular gene. Defects in the gene can lead to health conditions that can lead to fertility problems. These conditions include cystic fibrosis, Tay-Sachs disease, spinal muscular atrophy, Canavan disease, sickle cell disease, and thalassemia. Chromosomal abnormalities include changes in the number or structure of chromosomes that carry DNA. These changes often affect multiple genes. The normal number of chromosomes for men is 46. Women have 22 pairs of autosomes and two X chromosomes. Males have 22 pairs of autosomes and one X and one Y chromosome. Examples of chromosomal abnormalities are Down’s syndrome (Trisomy 21 – another chromosome 21), Turner’s syndrome (loss of X chromosome), and Klinefelter’s syndrome (excess X chromosome in men).
In men, chromosomal abnormalities may be associated with low sperm counts. Deletions of the Y chromosome gene and mutations in the cystic fibrosis gene may be associated with azoospermia or sperm insufficiency. Mutations in the cystic fibrosis gene can also lead to the loss of sperm-transmitting channels. Genetic testing is recommended for all men who do not have sperm (azoospermia) or low sperm count. In women, chromosomal abnormalities may be associated with miscarriage or even clinical conditions in children, such as Down’s syndrome.
Genetic diseases that cause female infertility
If cases of endometriosis or early menopause occur in their family, these women have an increased chance of a difficult pregnancy.
Other chromosomal abnormalities or gene mutations can also cause female infertility, especially affecting a woman’s ability to ovulate. Examples of both include:
• Mutations in the cystic fibrosis gene can result in poor nutrition in women, resulting in stronger cervical mucus or ovulation problems.
• Kallmann syndrome can cause female infertility due to the inability of her body to produce pituitary or hypothalamic hormones.
• Primary ciliary dyskinesia is a chronic respiratory infection (a disease of the airways or parts of the lungs) that causes infertility in women due to abnormal cilia in the fallopian tubes.
Genetic diseases that cause male infertility
Other chromosomal abnormalities or gene mutations cause male infertility, especially sperm production or obstruction. However, male infertility caused by the mutation is less common or incomprehensible to others. Examples of both include:
• Mutations in the cystic fibrosis gene can result in congenital vas deferens affecting male sperm flow.
• Klinefelter’s syndrome is a condition that men encounter when they are born with an extra x chromosome that affects sperm and testosterone production.
• Deleting the Y chromosome (the missing part of the Y chromosome) can prevent a man from reaching a normal sperm count.
Infertility is rarely attributed only to genetic factors. In most cases, there are multiple causes of infertility. The more of these factors can be identified and addressed, the more likely it is that infertility treatment will be effective. Fortunately, infertility treatment has been around for many years and is still improving. Even genetic factors can often be overcome with appropriate treatment protocols.
Other genetic conditions that affect fertility are more common in some populations: Tay Sachs disease (Ashkenazi Jews and French Canadians), Canavan disease (Ashkenazi Jews), sickle cell disease (African Americans, Hispanics, and the Mediterranean), and Thalassemia (Mediterranean, Middle East). )). and East Asia). CIRS physicians may recommend genetic testing for a gene defect as part of the initial infertility assessment, especially if the partner is from one of these ethnic groups or if the partner has a family history of certain diseases, such as cystic fibrosis.
The history of recurrent miscarriage also requires chromosomal testing of both partners.
If a genetic or chromosomal abnormality is found during your assessment, your doctor may recommend genetic counseling to obtain a detailed family genetic history and a risk assessment. Preimplantation genetic diagnosis (PGD) or preimplantation genetic screening can be performed to screen embryos for genetic conditions prior to implantation. PGD involves removing one or two cells from the embryo on day 3 or 5 and genetic analysis of the biopsied cell(s).