Table 1.

Major Familial Forms and Genetic Factors of Parkinson’s Disease.

PD Inheritance	Disease, (Mutations)	Gene, Location	Gene Function	Phenotype
Autosomal dominant	PARK-SNCA, (A53T, duplication, triplication)	SNCA, 4q22-1	The SNCA gene codes for the alpha-synuclein protein that is widely expressed in presynaptic terminals of neurons. Alpha-synuclein maintains the production of vesicles involved in neuronal communication. Alpha-synuclein is also thought to play a role in dopamine expression of voluntary and involuntary movement pathways.	Early-onset PD. Neurodegeneration within the SNpc and Lewy Body formation throughout the brain.
	PARK-LRRK2, (G0219s, R1441C)	LRRK2, 12q12	Encodes the leucine rich repeat kinase 2 protein, expressed in the cytoplasm and mitochondrial membranes of neurons. LRRK2 is heavily involved in the ubiquitination of molecules, leading to their degradation. The precise function in PD is not known, but it is thought to coordinate neuronal survival and differentiation in the midbrain.	Late-onset PD with mixed neuropathology. Some cases present with Lewy Body formation and DAn death in the SN, others without Lewy Body formation.
Autosomal recessive	PARK-DJ1, (Q456X, V170G)	DJ-1, 1p36.23	Encodes the protein DJ-1, found in the brain and other tissues throughout the body. DJ-1 is a multi-functional protein with roles involved in the prevention of alpha-synuclein aggregation, neuronal protection under conditions of oxidative stress, transcriptional regulation and prevention of metal-induced cytotoxicity. All or some of these functions may be involved in some types of early PD formation.	Conclusive data has not been reported.
	PARK-PINK1, (exon 7 deletion)	PINK1, 1p36.12	Codes for the protein PTEN-induced putative kinase 1, located within mitochondria. PINK1 exhibits a protective function of mitochondria during cellular stress by causing the parkin protein to bind to depolarized mitochondria and induce autophagy.	Early-onset PD complete with Lewy Body formation and acute DAn loss in the SNpc.
Genetic risk factor	Gaucher Disease (L444P, N370S)	GBA, 1q22	Codes for an enzyme active in lysosomes and cellular membranes. Beta-glucocerebrosidase is a housekeeping enzyme hydrolyzes the beta-glucosidic linkage of glucocerebroside into glucose and ceramide. Mutation causes glucocerebroside buildup in macrophages.	Severe neurological complications in addition to liver failure, bone lesions and low blood cell counts.