In 1997, scientists described the first gene known to be mutated, or changed, in PD. The gene named SNCA, or PARK1 (the first in a series of PARK genes that now number more than a dozen) codes for alpha-synuclein, a protein that we have since learned may play a very important role in the development of PD. While mutations in this gene are very rare, the discovery that an alteration of alpha-synuclein is involved in PD spurred researchers to study it. They found that this protein is present in the Lewy body, a foreign inclusion in neurons that is the pathologic hallmark for PD.