Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Disease-causing genetic mutations in sperm increase with men’s age


Scientists from the McKusick-Nathans Institute for Genetic Medicine at Johns Hopkins may have discovered why a rare genetic disease is more common in children born to older fathers. The disease, Apert syndrome, leads to webbed fingers and early fusion of the skull bones and must be corrected by surgery.

While Apert syndrome itself affects only 1 in 160,000 births, the scientists believe their findings could extend to many of the 20 or so other genetic conditions similarly linked to older fathers. The researchers are scheduled to present their findings Oct. 17 at the annual meeting of the American Society for Human Genetics in Baltimore.

"It makes sense that the mutations causing these diseases would occur more frequently in older men, and indeed that’s what we saw for Apert syndrome," says Ethylin Jabs, M.D., director of the Center for Craniofacial Development and Disorders at Johns Hopkins.

Importantly, disorders linked to advancing paternal age begin to increase rapidly at about the same time as maternal risks increase -- age 33 to 35. Until now, the only evidence for paternal age effects has come from determining how many children with these diseases are born to fathers of various ages.

To obtain the first genetic explanation for these effects, the scientists studied sperm from about 60 men of various ages and looked for two genetic changes responsible for 99 percent of the cases of Apert syndrome. They found that men over 50 were, on average, three times as likely as men under 30 to have sperm with at least one of these changes. The mutations were not more common in blood samples as men aged.

The scientists say it’s likely that the number of cell divisions that go into making a sperm plays a large role in the link between Apert syndrome and paternal age, and represents a fundamental difference between how aging egg and sperm can impact the health of a child.

"In the men we studied, these mutations had not been inherited, but rather collected over time in the reservoir of primitive cells that become sperm," says first author Rivka Glaser, a graduate student in human genetics at the Johns Hopkins School of Medicine.

Cells that mature into eggs are essentially frozen in time from puberty until the time the egg is signaled to develop. Because of the stage at which they are "frozen," the most likely error in an egg is to have an abnormal partitioning of chromosomes, producing an egg with an extra copy or a missing copy, Glaser says. For example, in Down syndrome, an extra copy of chromosome 21 is inherited from the mother.

Sperm, on the other hand, are continually produced throughout a male’s lifetime from a reservoir of primitive cells. These primitive cells, like other kinds of so-called stem cells, can either replicate themselves or take a step closer to becoming a sperm, a process called differentiation. All told, these cells divide every 21 days after puberty, and at each cell division the opportunity exists for an error in copying the DNA.

"Literally hundreds of millions of sperm are made in each batch, so in most cases there are still many normal sperm available," says Jabs, also a professor of pediatrics. Their study showed that "high levels" of mutations among men who had no children with Apert syndrome amounted to roughly 3 sperm with the mutation among 100,000 sperm.

If an error is made in any of the steps toward becoming a sperm, the only cells affected are the resulting sperm for that batch. However, if an error appears in a primitive cell as it replicates itself and the mistake isn’t fixed, the mutation will continue to be passed on to all of its progeny, including subsequent primitive cells and other batches of semen.

As men age, more of these primitive cells have collected mutations that cause Apert syndrome, leading to more sperm with the mutations in each batch of semen, the scientists suggest. The risk of having a child with Apert is about six times higher for a man age 52 than for someone who’s 27.

Authors on the study are Glaser, Jabs, and Rebecca Schulman, of Johns Hopkins School of Medicine, and Karl Broman, of the Johns Hopkins Bloomberg School of Public Health.

Abstract # 1127 "Molecular evidence for the paternal age effect in sperm." R. Glaser, et al.

Joanna Downer | EurekAlert!
Further information:

More articles from Health and Medicine:

nachricht Resolving the mystery of preeclampsia
21.10.2016 | Universitätsklinikum Magdeburg

nachricht New potential cancer treatment using microwaves to target deep tumors
12.10.2016 | University of Texas at Arlington

All articles from Health and Medicine >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>