Male genetics and infertility

In humans, chromosomes are the structures within cells that carry genetic information. Each human cell typically contains 23 pairs of chromosomes, for a total of 46 chromosomes. One of these pairs is the sex chromosomes, which play a crucial role in determining an individual’s biological sex.

Women have a 46XX and men 46XY configuration.

Typically, in individuals with male biological characteristics, they have one X chromosome and one Y chromosome in their sex chromosome pair. So, the “46” denotes the total number of chromosomes, and the “XY” specifies the configuration of the sex chromosomes.

The presence of a Y chromosome is particularly important as it contains genes crucial for male sex determination and sperm production. Abnormalities in Y chromosome structure or gene mutations can lead to reduced sperm production (oligospermia) or complete absence of sperm (azoospermia)

Some common genetic factors associated with male infertility include:

AZF Microdeletions

AZF: This stands for “Azoospermia Factor.” Azoospermia means the absence of sperm in the ejaculate, which can result in infertility.

Microdeletion: A microdeletion refers to a small missing piece of genetic material within a chromosome.

So, when we talk about “AZF microdeletion,” we’re referring to a small missing piece of genetic material specifically within certain regions of the Y chromosome. These regions, known as the AZF regions, contain genes that are essential for sperm production.

When someone has an AZF microdeletion, it can affect their ability to produce sperm, leading to infertility or reduced fertility. The specific effects depend on which AZF region is affected and the size of the deletion.

In simpler terms, it’s like a tiny part of the instruction manual for making sperm is missing, which can cause problems with sperm production and fertility.

Klinefelter syndrome

This genetic disorder results from an additional X chromosome in males (47,XXY), instead of the typical XY chromosome pattern. Klinefelter syndrome is associated with small testes, low testosterone levels, and impaired sperm production, leading to infertility or subfertility.

ADD IN KLINEFELTER LINK TO OTHER PAGE PLEASE

Cystic fibrosis gene abnormalities

Cystic fibrosis (CF) is a genetic condition that affects the body’s ability to produce a certain protein called the cystic fibrosis transmembrane conductance regulator (CFTR). This protein is crucial for controlling the flow of salt and water in and out of cells, especially in the lungs and digestive system.

This is also associated with male infertility, as the reproductive system also relies on the CFTR protein for normal function. This protein helps create an environment in the reproductive tract that allows sperm to swim and survive.

In individuals with cystic fibrosis (and in some men who may have a problem with one of the genes and no other symptoms, so they would have no idea – what we call “a trait”), the CFTR protein may not work correctly or may not be produced at all due to mutations in the CF gene. When this happens, it can lead to a condition called congenital bilateral absence of the vas deferens (CBAVD).

The vas deferens is the tube that carries sperm from the testes to the urethra during ejaculation. When it’s absent or blocked (as in CBAVD), sperm cannot reach the semen, leading to infertility in males with cystic fibrosis. But the good news is that sperm can still be obtained using a surgical sperm retrieval.

Chromosomal abnormalities

Structural or numerical abnormalities in other chromosomes, such as autosomes (non-sex chromosomes), can also impact sperm production and fertility. Conditions like chromosomal translocations, inversions, or deletions may disrupt normal spermatogenesis and contribute to male infertility.

Pippa Sangster has good links with genetic counsellors who can provide much more in depth information about any anomaly and what it may mean for your fertility.