According to the data of one of the largest DNA Banks in the world, his risk of developing Parkinson's disease is lower than he thinks

Mr Brin, the co-founder of Google and one of the richest men in the world, has recently disclosed that he carries mutation G2019S of gene LRRK2, also called PARK8 because it is associated with hereditary and non hereditary forms of Parkinson's disease.

In his blog he claims that such carriers have a chance of developing the disease i.e. a "penetrance" that "is somewhere between 20% and 80%" - a piece of information that he presumably gleaned from the study by the International LRRK2 Consortium, published in Lancet Neurology earlier this year.  We contributed to the study and know that in this study penetrance was strongly influenced by hereditary cases, which may have overestimated it, as claimed in the editorial by Elbaz published together with the article.   

We have performed a study on the penetrance of the mutation at our centre, the ICP Parkinson Institute in Milan (Italy), which hosts one of the largest DNA Banks in the world related to movement disorders: at the moment it stores 4,000 DNA samples, out of which 2,400 from patients with Parkinson's disease.  According to our study, which included both hereditary and non hereditary cases, penetrance was age-dependant and reached a maximum of 32% at 80 years of age.  A similar penetrance at 80 years of age (26%) was found by Clark et al in Ashkenazi Jews.