Google co-founder Sergey Brin has started a personal blog and revealed that he has a genetic predisposition to Parkinson's disease.

Brin gave no reason for starting the tooblogspot.com blog on the Blogger system, which is owned by Google.

In his first post, called LRRK2, he spoke about his mother's experience of Parkinson's and wrote that he decided to undergo tests to determine the likelihood that he will suffer from the condition.

Brin took a test with genetic screening service 23andMe which was set up by his wife Anne Wojcicki. The results show that he has a mutated gene named G2019S which makes it more likely that he will suffer from Parkinson's later in life.

"Early studies tend to have small samples with various selection biases. Nonetheless it is clear that I have a markedly higher chance of developing Parkinson's in my lifetime than the average person," he wrote.

"In fact, it is somewhere between 20 per cent and 80 per cent depending on the study and how you measure."

Brin said that the discovery is quite encouraging, in that he can take preventative action such as regular exercise and start funding research into the disease.

23andMe has recently started something of a price war among genetic screening companies by cutting its prices by more than 50 per cent to $399.

The company has also started an aggressive promotional campaign, including " spit parties" at New York fashion week at which people gave saliva samples to have their genetic material analysed.

However, medical experts have warned that such tests can be highly misleading if genetic predispositions are not properly understood and the results are not carefully analysed.

They also warned that the stress of receiving adverse results can actually exacerbate certain health issues.