Sergey Brin, co-founder of Google, and Anne Wojcicki, co-founder of 23andMe, announced a $50-million challenge spurring existing and new donors at every level to give, or increase giving, to The Michael J. Fox Foundation for Parkinson’s Research. The Challenge is now in effect and will match all new or increased gifts to The Michael J. Fox Foundation on a one-to-one basis through year-end 2012.