A Look at 4 Causes of Genetic Infertility in Men
Of the 15 percent of American couples who experience infertility problems each year, roughly 50 percent have issues that stem in full or in part from male-factor infertility. Of these cases, nearly half are due to defined causes, such as unhealthy lifestyle choices, hormone imbalances, scarring from past surgeries, or blockages within the reproductive system. The remaining 50 percent of male-factor infertility cases are attributed to genetic issues or undefined problems, though a majority of cases where the root cause of male infertility is unknown are also likely to be rooted in genetic abnormalities.
The effects of genetic male infertility vary on a case-by-case basis, but it’s important for couples to understand the circumstances that surround such conditions. Listed here are four of the more commonly identified genetic conditions that cause male infertility:
One of the most common causes of both male and female genetic infertility is a chromosomal abnormality known as translocation. This condition refers to a structural issue within a person’s DNA in which part of a chromosome separates from itself and attaches to another chromosome. In some cases, a person born with chromosomal translocation can suffer from debilitating health issues, but in other cases no signs of the condition manifest until that person attempts to have children. Translocation often results in repeated miscarriages for a couple due to the fact that the cell division which occurs during reproduction can cause a fetus to receive missing or extra genetic material. Depending on the genes affected, this uneven split of chromosomes can render a fetus unviable, thus leading to miscarriage.
Repeated attempts to conceive may eventually allow some men with chromosomal translocation to naturally conceive a child, but this strategy for conception comes with risk. Firstly, repeated miscarriages which require a dilation and curettage procedure can cause a buildup of scar tissue within the uterus of the female partner. Additionally, chromosomal translocation may cause a child to be born with developmental problems. For these reasons, a fertility specialist may encourage a patient with chromosomal translocation to opt for in vitro fertilization (IVF) accompanied by a screening procedure known as preimplantation genetic diagnosis (PGD), in which only embryos free of chromosomal abnormalities are selected for uterine implantation.
2. Y chromosome microdeletions
Another common genetic condition that can cause severe male infertility is Y chromosome microdeletions, in which portions of genetic material that play an important role in sperm production are missing from the Y chromosome. Current research suggests that microdeletions occur spontaneously in male embryos, which means that a man affected by the condition will not necessarily have brothers or fathers who bear the same condition. However, a man who struggles with Y chromosome microdeletions will pass his genetic infertility along to any male children that he produces, whether they are conceived naturally or with the assistance of IVF. Female children born of a father with this condition will not pass along the trait, as they will receive his X chromosome, rather than the Y with the missing genetic material.
Some men affected by Y chromosome microdeletion will experience only mild infertility and be able to eventually father a child on their own, while others will be sterile; a man’s degree of infertility in these circumstances depends on the location of the deletions within his Y chromosome. Overall, most men with the condition can at the very least have sperm cells extracted from their testes and father a child via IVF, though a minority will be unable to produce any mature sperm cells for harvest.
3. Cystic fibrosis gene mutation, CAVD
Men who carry a mutation of the gene for cystic fibrosis (CF) are often born with a condition labeled congenital absence of the vas deferens, or CAVD, in which the tubes that transport sperm from the testes do not develop. The majority of men with CAVD maintain healthy, functional testes, but their bodies cannot transfer sperm through the reproductive tract to integrate with seminal fluid, which makes it impossible to impregnate a partner naturally. However, men with CAVD typically can become fathers with help of assisted reproductive technologies like sperm retrieval and intracytoplasmic sperm injection (ICSI).
Though CAVD can occur independently of the CF gene mutation, four out of five men with the condition do carry some form of CF gene mutation. For this reason, it’s important that any man with CAVD and his female partner undergo testing to determine whether or not they are both carriers of CF mutations. If both partners carry the gene, then their child is at significant risk of being born with cystic fibrosis, a debilitating and fatal illness for which there is no cure.
4. Klinefelter syndrome
Klinefelter syndrome, in which a man is born with the sex chromosomes XXY, occurs in approximately one in every 500 to 1,000 male births. The addition of the extra copy of the X chromosome in a man’s genetics occurs randomly during the formation of a parent’s reproductive cells and is not considered to be hereditary. The effects that Klinefelter syndrome can have on fertility include low to no sperm count, low testosterone levels, or a total absence of sperm within semen.
Men with Klinefelter syndrome must be evaluated on an individual basis in order to determine their options for infertility treatment, but the majority will not be able to father a child naturally. However, some men with the condition may be able to have sperm extracted from their testicles in order to conceive a child with a partner through ICSI.
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