35-year-old Google co-founder Sergey Brin started a blog named Too yesterday. It’s on Blogger, of course. MInimalist design of white type on a black background (which I find hard to read). Too is a play on “two” and on the fact that the blog is about his life outside work, according to Google Blogoscoped.

In his first post, titled LRRK2, he writes movingly about his mother’s Parkinson’s Disease, his wife’s personal DNA analysis company, 23andme – and about a mutation of the LRRK2 gene (G2019S) considered responsible for Parkinson’s. He reveals that through testing by 23andme, he has learned he has the mutant form of the gene, as does his mother. Depending on which study you believe, he writes, he has a 20 to 80 percent chance of developing the disease himself.

In my book I question whether the super famous can write a credible CEO blog (I use Oprah Winfrey and Bill Gates as examples). Well, Sergey is proving it’s quite possible, particularly when the topic is something important. I wonder whether his comments will prompt others to consider gene testing.

Edelman CEO Richard Edelman wrote in September 2007 about being tested for prostate cancer (and the scare of a high PSA). It started an impassioned discussion about PSA screening on his blog. I just noticed he’s written an update this week (Sept. 17, 2008) saying he’s had a radical prostatectonomy. He says he expects his cancer has been completely eliminated.

Note: as of this writing, there appear to be zero comments on Sergey’s blog. I clicked through to leave one and found this disclaimer: “While I would like to receive and post many insightful comments, realistically I am unlikely to be able to read through all of them and may accept very few or none at all. Thank you for your understanding.” I left one anyway, saying “kudos.”