• The Effects of telomere length in infertility and reproductive health
  • Mohammad Hossein Madahali,1,*
    1. Department of Anatomical sciences and cell biology ,Mashhad University of Medical Sciences ,Mashhad ,Iran


  • Introduction: Telomeres, which means "end part" in Greek, are special structures made of nucleoproteins located at the ends of eukaryotic chromosomes. They are essential for proper cell division and were recognized in the early 20th century for their role in protecting chromosome integrity. Telomeres prevent chromosome ends from being mistaken for DNA damage, which could cause genetic instability. They consist of short, repetitive noncoding sequences that safeguard genetic information and slow down the wear of chromosomes over time. In germ cells, telomeres remain stable, playing a critical role in reproduction and fertility. Telomerase, an enzyme made of two subunits, prevents telomere shortening during cell division, allowing for continued cell division, and is often active in cancer cells. Human telomeres consist of repeats of the sequence 5'-TTAGGG-3' and vary in length. They shorten due to factors like incomplete replication or exposure to harmful substances. Length variations in telomeres affect aging and the likelihood of age-related diseases. Healthy lifestyle choices can help maintain telomere length, contributing to overall health and fertility. In recent years, male infertility has become more common, contributing to half of all infertility cases globally. The cause of sperm abnormalities is unknown in nearly half of these cases, classified as idiopathic. Various factors like genetics, lifestyle, and environmental influences lead to these issues, often in combination. Research is focused on the molecular pathways related to male infertility. Assessments typically evaluate semen quality, specifically sperm count, motility, and morphology, but standard analyses may not always identify abnormalities. New tests are being developed to better assess sperm quality and performance, especially in men whose semen parameters appear normal. Recent studies suggest a link between telomeric instability and gamete quality, indicating that telomere length may be a new marker for male infertility. Telomeres protect chromosome ends during cell division, and their gradual shortening can lead to decreased cell division and increased apoptosis. Paternal age negatively affects fertility, but longer telomeres in older fathers may offer some reproductive advantages. Research indicates a correlation between shorter telomeres and male infertility, especially regarding sperm quality. Being overweight or obese can further reduce telomere length and negatively affect fertility. Additionally, some studies explore the connection between telomeres and testicular cancer, but this relationship remains unclear.
  • Methods: The present study was conducted by reviewing related articles in Web of Science, Scopus, and PubMed databases.
  • Results: Telomeres are crucial for protecting chromosome ends and ensuring reproductive cell maintenance and fertility. Telomere length determines their function, with shortening beyond a critical point leading to loss of protection. Maintaining telomere length is essential, with telomerase playing a key role in this process. Telomerase, present in germ cells and cancer cells, helps maintain telomere length by adding new repeats. Sperm telomeres are typically longer due to delayed closure of telomerase, preventing shortening with age. Telomere length in sperm affects offspring's cells. Infertile men often have shorter telomeres and poorer sperm quality compared to fertile men. Short telomeres in sperm have been linked to male infertility. A study found low sperm count men had decreased telomere length, increased DNA damage, and protamine deficiency, indicating issues in cell division processes during spermatogenesis. This underscores the importance of telomere length in genomic stability and male fertility.
  • Conclusion: Male infertility has become a social issue, with conventional diagnostic methods often failing to identify underlying causes. Telomere length in sperm cells is being explored as a potential marker for male infertility, with studies linking it to abnormal sperm characteristics. Research suggests using quantitative PCR to measure telomere length could improve assessment of spermatogenesis and determine male reproductive age. While direct selection of germ cells with known telomere profiles for ART procedures isn't feasible, measuring telomere length in the polar body may provide indirect prediction. Longer telomeres in sperm could positively impact fertility, potentially offering solutions for infertility cases. Antioxidant therapies have shown mixed effects on chromatin integrity in male infertility treatment, requiring further research for validation. Telomere length could serve as a potential biomarker for sperm quality and male infertility, but more extensive studies are needed to confirm the connection with semen quality and fertility.
  • Keywords: telomere length- infertility- reproductive health