A new study from Huntsman Cancer Institute (HCI) at the University of Utah has revealed that the father's sperm delivers much more complex genetic material to the egg than previously thought. This finding may lead to a diagnostic test to help couples deal with infertility.
The researchers say that they have found particular genes packaged in a special way within the sperm, and that may promote the development of the foetus.
"Our findings show that the father plays an active role in packaging his genome to help ensure a healthy baby," Nature magazine quoted study co-leader Dr. Brad Cairns, investigator with HCI and the Howard Hughes Medical Institute, and professor of oncological sciences at the University of Utah, as saying.
"However, they also raise the possibility that a man's aging, health and lifestyle may alter this packaging and negatively affect fertility and embryo development," the researcher added.
Certain genes play key roles in the creation of organs and tissue during foetal development.
The new study shows that these genes are wrapped in special packaging materials in sperm, known as 'modified histones'.
The researchers say that these modified histones appear to be key factors in ensuring genes are activated or repressed at the right level, place and time, which helps the fertilized egg develop properly.
Understanding how these genes are activated or repressed leads to a better understanding of how disorders like birth defects and cancer develop.
"Genes have on-and-off switches, and understanding them allows us to target them, leading to possible treatments, cures or prevention strategies. That's the good news," says Cairns.
An implication of this study is that factors like genetic mutations, age or lifestyle may affect sperm chromosome packaging, leading to infertility.
"We are hopeful that this work will soon lead to a clinical diagnostic test that will help couples with infertility problems make better informed decisions regarding their prospects for a healthy child.
We will also be testing if aspects of a man's lifestyle - such as age, diet or health - affect proper packaging and fertility," says Cairns.
The research team are not planning to study how decision-making genes are packaged in eggs, which remains a major mystery.