MOUNTAIN VIEW, Calif.  Sergey Brin, a Google co-founder, said Thursday that he has a gene mutation that increases his likelihood of contracting Parkinson’s disease, a degenerative disorder of the central nervous system that can impair speech, movement and other functions.

Mr. Brin, who made the announcement on a blog, says he does not have the disease and that the exact implications of the discovery are not clear. Studies show that his likelihood of contracting Parkinson’s disease in his lifetime may be 20 percent to 80 percent, Mr. Brin said.

Mr. Brin, whose personal fortune was recently pegged at $15.9 billion by Forbes, ranking him as the 13th richest American, said that he may help provide more money for research into the disease.

Through a Google spokesman, Mr. Brin declined to be interviewed for this article.

Mr. Brin said he learned that he carries a mutation of the LRRK2 gene, known as G2019S. His mother, Eugenia Brin, also carries the gene mutation and has Parkinson’s.