What is macrozoospermia?
Macrozoospermia is a condition that affects only males. It is characterized by abnormal sperm and leads to an inability to father biological children (infertility).
In affected males, almost all sperm cells have abnormally large and misshapen heads. The head of the sperm cell contains the male's genetic information that is to be passed on to the next generation. Normally, the head of a sperm cell contains one copy of each chromosome. In men with macrozoospermia, the sperm cell head contains extra chromosomes, usually four copies of each instead of the usual one. This additional genetic material accounts for the larger head size of the sperm cell. Additionally, instead of having one tail (flagellum) per sperm cell, affected sperm have multiple flagella, most often four.
Because of the additional genetic material, if one of these abnormal sperm cells combines with an egg cell, the embryo will not develop or the pregnancy will result in miscarriage.
How common is macrozoospermia?
Macrozoospermia is estimated to affect 1 in 10,000 males in North Africa. The prevalence of the condition outside this region is unknown.
What genes are related to macrozoospermia?
Mutations in the AURKC gene cause macrozoospermia. The AURKC gene provides instructions for making a protein called aurora kinase C. This protein is abundant in male testes, which are the male reproductive organs in which sperm are produced and stored. In the testes, this protein regulates the division of sperm cells. Aurora kinase C ensures that the mechanisms for cell division are in place and helps chromosomes properly align with each other so that every new sperm cell contains one copy of each chromosome after cell division.
AURKC gene mutations that cause macrozoospermia lead to the production of a nonfunctional protein or a protein that is quickly broken down. This lack of aurora kinase C blocks cell division in sperm cells. Without cell division, the chromosomes are not split among multiple new sperm cells. As a result, affected sperm cells contain extra chromosomes, usually four copies of each instead of the usual one.
Read more about the AURKC gene.
How do people inherit macrozoospermia?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Where can I find information about diagnosis or management of macrozoospermia?
These resources address the diagnosis or management of macrozoospermia and may include treatment providers.
- American Society for Reproductive Medicine: Sperm
- Centers for Disease Control and Prevention: Infertility
- Genetic Testing Registry: Infertility associated with multi-tailed spermatozoa and excessive
- MedlinePlus Encyclopedia: Semen
You might also find information on the diagnosis or management of macrozoospermia in Educational resources and Patient support.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about macrozoospermia?
You may find the following resources about macrozoospermia helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for macrozoospermia?
- infertility associated with multi-tailed spermatozoa and excessive DNA
- large-headed multiflagellar polyploid spermatozoa
- spermatogenic failure 5
What if I still have specific questions about macrozoospermia?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
- What does it mean if a disorder seems to run in my family?
- What are the different ways in which a genetic condition can be inherited?
- If a genetic disorder runs in my family, what are the chances that my children will have the condition?
- Why are some genetic conditions more common in particular ethnic groups?
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding macrozoospermia?
autosomal ; autosomal recessive ; cell ; cell division ; chromosome ; DNA ; egg ; embryo ; gene ;infertility ; inherited ; kinase ; polyploid ; prevalence ; protein ; recessive ; sperm ; spermatozoa ;testes
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (6 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook