Macrozoospermia (Macrozoospermia) - Gen AURKC.

The macrozoospermia is a disorder that affects only males, characterized by abnormal sperm causing infertility. In males affected almost all sperm cells have abnormally large and misshapen heads. Normally the head of a sperm contains one copy of each chromosome. In men with macrozoospermia, the sperm head contains extra chromosomes, usually four copies of each rather than the usual. This additional genetic material generates a larger head size sperm cell. Also, instead of having a scourge for sperm cell, sperm affected have multiple flagella.

This process is due to mutations in the gene AURKC, located on the long arm of chromosome 19 (19q13.43). This gene encodes the protein aurora kinase C. This protein regulates certain events during cell division, helping to dividing cells separated from each other and ensuring that these cells each contain a complete set of chromosomes. Aurora kinase C is more abundant in the male testes, where it regulates the division of sperm cells, ensuring that each new sperm cell is divided properly and contains a copy of each chromosome.

They have been described at least four mutations in the gene responsible for macrozoospermia AURKC. These genetic changes lead to encoding a nonfunctional protein or a protein that rapidly decomposes. A common mutation in males of North African descent eliminates one gene nucleotide AURKC (144delC). The protein encoded from the altered gene is abnormally short, nonfunctional. Lack of aurora kinase C blocks cell division in sperm cells. As a result, sperm have extra chromosomes, usually four copies of each rather than the usual. This increase in the number of chromosomes enlarges the sperm head and leads to the presence of multiple flagella. Because of the additional genetic material, if one of these altered sperm combines with an egg, the embryo does not develop or pregnancy leads to spontaneous abortion.

This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.

Tests in IVAMI: in IVAMI perform detection of mutations associated with macrozoospermia, by complete PCR amplification of the exons of the gene AURKC, and subsequent sequencing.

Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).