Researchers have developed a new test that quickly and easily identifies when sperm are harbouring chromosomal mutations. Experts can use this technique for men hoping to have children.
Genotoxicity of cancer therapies
Ongoing improvements in survival rates with gonad-sparing protocols for children and adolescents with cancer have increased optimism of survivors to become parents after treatment. However, cancer therapies, such as radiation and drugs, are genotoxic. This raises concerns of abnormal pregnancies, birth defects and heritable mutations in exposed individuals.
While some studies have shown that the risk of mutated sperm diminishes over time, for most chemotherapeutic drugs there is still no information on their impact on DNA mutations to human sperm. Additionally, there are currently no efficient and affordable tests that researchers can use to track men’s germ cell health. In other words, no current tests can allow researchers to identify when sperm cells are carrying mutations or structural abnormalities from treatment.
Adapting FISH to find sperm
In a paper published in the journal PLOS ONE, an international team reported the success of adapting fluorescence in situ hybridisation (FISH) to probe sperm DNA for a wide variety of chromosomal defects simultaneously. This version of FISH is called the AM8 sperm FISH protocol and is the result of decades of work. The team reported results from nine Hodgkin Lymphoma (HL) patients, who provided semen samples before treatment, and/or during treatment, and/or at various times after treatment with combination NOVP chemotherapy and radiotherapy.
Results from the FISH protocol tests revealed that sperm produced during HL treatment had ten times more chromosomal defects compared with those produced prior to treatment. They found that six months post-treatment, patients’ sperm had return to pre-treatment quality.
This study indicates that this protocol is a promising tool for assessing an individual’s burden of sperm carrying chromosomal structural aberrations and aneuploidies after cancer therapy. This has broad applications in other clinical and environmental situations that may pose risks to human spermatogenesis.
Andrew Wyrobek, study lead, stated:
“We are excited by these results because they are a first step toward applying this method to any human situation – such as ageing, illness, drugs, or exposure to environmental toxicants – to determine genetic risks to male germ cells and to examine the persistence of chromosomally damaged sperm.
We believe this approach has a wide range of applications in healthcare and family planning, as it can be used to identify environmental exposures that increase the risk for producing chromosomally abnormal sperm that can affect the health of future pregnancies and children for generations to come.”