An international team of researchers, led by Lawrence Berkeley National Laboratory biophysicist Andrew Wyrobek, developed a technique for detecting chromosomal abnormalities in sperm.
The technique — AM8 fluorescence in situ, or AM8 FISH protocol — is able to detect a wide range of abnormalities simultaneously. Chromosomal mutations in sperm and egg cells, collectively known as germline cells, can result in significant fetal and birth defects.
“When sperm with these chromosomal abnormalities fertilize an egg, the resulting fetus and live-born child may have severe health issues,” Wyrobek said in a press release. “For example, fetuses with trisomy 18 — an extra copy of chromosome 18 or a fetus with an unbalanced chromosomal rearrangement — typically die in utero or within a year of birth.”
According to campus professor of cell and developmental biology Abby Dernburg, chromosome rearrangements often result in sperm production halting altogether, and most spontaneous birth defects are due to chromosomal abnormalities in the egg cell. The participants in this study, according to Dernburg, were able to produce sperm but probably suffered stem cell damage, which would still be harmful for any progeny resulting from this sperm.
The study found that sperm produced by participants during a multidrug and radiation treatment had 10 times more chromosomal defects compared to prior samples. Yet, six months after treatment, their sperm had returned to pre-treatment quality.
According to Dernburg, an important fact to note is that this technique is designed to detect large-scale changes, rather than single base changes.
“They’re analyzing sperm from patients to see what the frequency of errors is, but those sperm are not making a baby,” Dernburg said. “It’s only good for assessing the overall sperm health in a particular patient.”
The study focused on the impact this could have on male cancer patients, as chemotherapy and radiation therapy are known to damage DNA in not only cancerous cells, but noncancerous ones. While there already exists testing for sperm, it is costly and comparatively ineffective in identifying chromosomal mutations.
Wyrobek said in the press release that with additional testing and commercial development, this approach could be used in family planning and identifying environmental factors that impact chromosome defects, but it will take some time for it to be available on a large scale.
“We are excited by these results because they are a first step toward applying this method to any human situation — such as aging, illness, drugs, or exposure to environmental toxicants — to determine genetic risks to male germ cells and to examine the persistence of chromosomally damaged sperm,” Wyrobek said in the press release. “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.”