PINK1 and Parkin, the products of two genes responsible for autosomal recessive Parkinsonian syndromes with early onset, act as a quality control system on the outer mitochondrial membrane to preserve mitochondrial integrity.
Two new AREP loci (PARK6 and PARK7) have been recently mapped on chromosome 1p and confirmed in independent datasets, suggesting that both might be frequent.
Our data indicate that olfactory dysfunction is common in PINK1Parkinsonism and consists typically in defective odor identification and discrimination.
The aim of this study was to elucidate whether sensory abnormalities are present and may precede motor symptoms in familial parkinsonism by characterizing sensory function in symptomatic and asymptomatic PINK1 mutation carriers.
Mutations associated with early-onset autosomal recessive parkinsonism have been identified in the Parkin gene, and recently a second gene, PARK6, involved in early-onset recessive parkinsonism was localized on chromosome 1p35-36.
Recent evidence from studies on the genetic forms of parkinsonism with particular stress on DJ-1, parkin, and PINK-1 also suggest the involvement of mitochondria and oxidative stress.
Mutations in seven genes are robustly associated with autosomal dominant (SNCA, LRRK2, EIF4G1, VPS35) or recessive (parkin/PARK2, PINK1, DJ1/PARK7) Parkinson's disease (PD) or parkinsonism.
Mutations in PINK1 (PTEN-induced putative kinase 1) are causal for early onset recessive parkinsonism in humans, characterized by damage to the nigrostriatal system.
The identification of a higher number of patients (5%) than controls (1%) carrying a single heterozygous mutation, along with previous positron emission tomography studies demonstrating a preclinical nigrostriatal dysfunction in PARK6 carriers, supports the hypothesis that haploinsufficiency of PINK1, as well as of other EOP genes, may represent a susceptibility factor toward parkinsonism.