Male infertility due to large-headed multiflagellar polyploid spermatozoa

Male infertility due to large-headed multiflagellar polyploid spermatozoa (also known as macrozoospermia) is a rare genetic condition affecting male reproductive function. It is characterized by the presence of abnormal sperm cells that have enlarged heads (macrocephalic), multiple flagella (tails), and an abnormal number of chromosomes (polyploidy). The condition is a specific form of teratozoospermia, meaning the sperm have abnormal morphology. Affected men are typically identified during fertility evaluations, as the condition leads to primary male infertility. The abnormal sperm are unable to successfully fertilize an egg naturally due to their structural and chromosomal abnormalities. The most commonly identified genetic cause of this condition is homozygous mutations in the AURKC gene (Aurora Kinase C), located on chromosome 19q13.43. Aurora Kinase C plays a critical role in meiosis, the cell division process that produces sperm cells. When this gene is dysfunctional, meiotic division fails to complete properly, resulting in spermatozoa that are diploid or polyploid rather than haploid, with correspondingly enlarged heads and multiple tails. The condition has been particularly reported in North African populations, where a specific founder mutation (c.144delC) in AURKC has been identified at a relatively higher carrier frequency. Currently, there is no curative treatment for this condition. Natural conception is not possible due to the severe sperm abnormalities. Conventional assisted reproductive technologies such as intracytoplasmic sperm injection (ICSI) have generally shown poor outcomes because the injected sperm carry an abnormal chromosomal complement, leading to failed fertilization, abnormal embryo development, or early pregnancy loss. Genetic counseling is recommended for affected individuals and their families. Donor sperm insemination remains an alternative option for couples seeking to have children. Research into improved selection techniques for rare normal sperm within the ejaculate is ongoing but remains experimental.

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