'Every person has 60 different genetic mutations'

A research by the Wellcome Trust Sanger Institute in Cambridge and two other institutes in the US and Canada showed that a person receives up to 60 mutations in his or her genome from parents.

It shows that human genomes (our genetic makeup carried on 23 pairs of chromosomes) are mutated in both sperm and egg cells, resulting in changes to our DNA seen in neither parent, the Daily Mail reported.

It also suggests that genetic tests could run the risk of misdiagnosing patients with a high mutation rate because samples may not typify the mutations present in the rest of the body, the researchers said.

The research also confounded previous theories over whether most mutations came from the mother or father, with results showing it varied dramatically in each individual. To try and ascertain how much of a "mutant" each human is, the scientists studied the genes of two families, both of which consisted of two parents and one child.

Looking for new mutations in the child, they combed through 6,000 possible mutations in each genome sequence. This proved extremely challenging, given that, on average, just one in every 100 million letters of DNA is altered each generation.

They also sorted mutations into those that occurred during the production of their parents' sperm or eggs, and those which happened after they were born. The results, published in journal Nature Genetics, surprised scientists as they found that in one family, 92 per cent of the child's mutations came from the father, while in another it was just 36 per cent.

Study author Dr Matt Hurles, from the Wellcome Trust Sanger Institute, said: "We now know that, in some families, most mutations might arise from the mother, in others most will arise from the father.

"This is a surprise: many people expected that in all families most mutations would come from the father, due to the additional number of times that the genome needs to be copied to make a sperm, as opposed to an egg."

Co-author Professor Philip Awadalla of the University of Montreal added: "Today we have been able to test previous theories through new developments in experimental technologies and our analytical algorithms.

"This has allowed us to find these new mutations, which are like very small needles in a very large haystack." The team plans to do further research into how factors like parental age and environment affects the number of mutations, and how they could use their findings to identify debilitating genetic diseases.