Sergey Brin, one of the billionaire founders of Google, announced last week that he is carrying a mutant gene regarded as an indicator of Parkinson’s disease.

Brin, 35, revealed that his DNA had been examined by 23andMe, a genetic testing company co-founded by his wife, Anne Wojcicki. The results showed that his genetic make-up included a mutation of a gene known as LRRK2, which several studies have linked to Parkinson’s.

Writing in a new blog, Brin acknowledged that the implications of his discovery were “not entirely clear”, but he added: “It is clear that I have a markedly higher chance of developing Parkinson’s in my lifetime than the average person.”

He cited studies that put that chance at anywhere between 20% and 80% — a margin that some researchers have said is too broad to be worth consideration. One New York neurologist noted that many people with Brin’s mutation, which is known to specialists as G2019S, never develop the disease.

Supporters of genetic testing argue that the DNA results provide important information about health probabilities that can inspire patients to take appropriate action. Critics have argued that the tests may cause psychological problems if patients begin to worry about diseases they may contract in decades ahead.

Brin declared himself “fortunate” to have learnt about his genetic make-up. His mother, Eugenia, has already been diagnosed with Parkinson’s, and a DNA test has revealed that she also carries the G2019S mutation.

“This leaves me in a rather unique position,” Brin wrote in his blog. “I know early in my life something I am substantially predisposed to. I now have the opportunity to reduce those odds.”

Brin and his parents have already donated nearly £1m towards research at the hospital in Baltimore where his mother has been treated. With a fortune estimated at £8.7 billion — which according to Forbes magazine makes him America’s 13th richest person — he may be inclined to spend millions more on research into what is currently an incurable disease.

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