Idiopathic Parkinson’s disease (PD) is an age-dependent, neurodegenerative disorder and is predominantly sporadic. Only 20–30% of patients have a positive family history for PD with a complex mode of inheritance. In a few extended families, the disease is inherited as an autosomal dominant trait. Linkage to chromosome 4 was reported in a large Italian kindred multiply affected by an early-onset form of PD (1). However, this finding was not replicated in a sample of 94 Caucasian families by Scott et al. (2), or in 13 multigenerational families by Gasser et al. (3)
