x Abu Dhabi, UAEMonday 24 July 2017

Older dads more likely to sire children with diseases, study claims

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ABU DHABI // A new study showing a link between a man's age and birth defects in his children could give rise to increased awareness in the UAE, where older men often father children, experts say.

The research, released in August by Decode Genetics, a research company based in Iceland, shows that as men age they are more likely to pass on genetic mutations to their offspring.

According to the study, the number of mutations passed on by the father is far more than those passed on by the mother. With every year a man ages, two new genetic mutations are passed to the child and with every 16 years, the number of mutations doubles.

Dr Abdul Razzak Hamzeh, senior scientific coordinator at the Centre for Arab Genomic Studies in Dubai, said he hoped the results would be an "eye-opener" for the community.

"A study like this could be very useful to making people aware of the risks," he said. "This society has a relatively high percentage of genetic and hereditary problems and it doesn't need more."

Dr Hamzeh said it has long been suggested that sperm contribute more small mutations to the offspring. What makes this study different, however, is that it looks at the entire genome rather than specific mutations. The mutations are more severe in women's genetic material.

Studies such as this one will make it more difficult for society to turn a blind eye to the role that a father's age plays, said Dr Soaad Al Oraimi, professor of gender and development at UAE University.

"We have known this for a while, but there has always been bias in what information is given attention," she said. "This study further shows this is a problem. We need to first acknowledge it and understand it before we can tackle it. But we must not ignore it."

Over the course of two years, researchers looked at the genomes of 78 parents and their offspring. They found that, on average, the mother contributes about 14 to 15 mutations to a child, while those from the father depend on his age, ranging from 39 mutations at 22 years old to more than 90 at age 40.

The findings shed light on the importance of the father's age as a risk factor for disease in his children, mainly schizophrenia and autism.

A 20-year-old man contributes between 50 and 60 per cent of new mutations, while a 40-year-old contributes about 70 per cent of the new mutations in the child, said Dr Kari Stefansson, chairman and chief executive of Decode Genetics.

Although there are no hard numbers for older fathers in the UAE, experts say there is a trend to have children later in life because it is accepted socially and culturally.

"In our society, there's no specific age at which we expect a man to get married or have children," Dr Al Oraimi said. "Age doesn't prevent him from having a family later in life. He may have certain circumstances, like he was divorced, finished his studies later or simply wants to marry again."

However, the trends of younger women marrying older men and polygamy are becoming less common, Dr Al Oraimi said, with these mainly seen among uneducated, low-income communities and in rural areas.

"Women are getting more educated and as a result more independent," she said. "They no longer accept [they have] to marry anyone. In fact, now we are faced with a declining birth rate. This can ultimately affect the social fabric and demographics of the country."

Experts say that data on the children of older fathers is key to tackling the problem.

"There's a very strong need for that," Dr Hamzeh said. "And there should be a follow-up to the children of such marriages. You would like to know the prevalence of these mutations and diseases among them. You also have a very important third-party component which is the response of genetic material to the environment."

Most mutations go into "junk" or uncoded DNA, meaning it will not affect the child. But if the mutations go into coded DNA, they can have detrimental effects, Dr Hamzeh said.

The findings of the study could be the first step to a paradigm shift in the way late-stage fatherhood is perceived, Dr Stefansson said.

"If you look at it at a social level, we have always been focusing on the age of the mother, which is more likely to be linked to Down syndrome and other rare chromosomal dysfunctions," he said. "But this study shows that the father's age is also important."