Four chromosomal loci (PARK2, PARK6, PARK7, and PARK9) associated with autosomal recessive, early onset parkinsonism are known. Positional cloning within the refined PARK7 critical region recently identified mutations in the DJ-1 gene in PARK7-linked families. Mutations in the PARK7/DJ-1 gene cause autosomal-recessive Parkinsons disease.