Older Fathers have High Chances of Having a Child with Noonan Syndrome

Older fathers are more likely to have children with Noonan syndrome, according to a new study.

The Noonan Syndrome affects many areas of the body. Children born with this syndrome have unusual facial features, short stature, skeletal problems, bleeding, and many other defects. The condition is present in one in about 1,000 to 2,500 people.

Norman Arnheim and Peter Calabrese and their team from University of South California have now found that a mutation that causes the disease increases in older fathers. This mutation in the sperm stem cells accelerates the cell to reproduce itself. So, the father is more likely to have a higher number of mutated sperms than healthy ones. The longer the man waits to become a father, the higher are the chances that the child will have Noonan syndrome.

The present study included a small study sample of 15 men who weren't affected by the Noonan syndrome. Researchers found that the new mutations in these men were clustered in the testis, and the number of these mutated stem cells increased with age.

"There is competition between stem cells with and without the mutation in each individual testis. But what is also unusual in this case is that the mutation which confers the advantage to testis stem cells is disadvantageous to any offspring that inherits it," said Arnheim in a news release.

The study provides an understanding of the molecular pathway through which a genetic disease mutation can manipulate the growth of disease-carrying sperms, increasing the prevalence of the genetic condition.

A recent study had also shown that older fathers have higher chances of having grandchildren with autism.

The study is published in The American Journal of Human Genetics.