while limiting glucose uptake and lactate production, thus preventing onset of the Warburg effect during tumourigenesis. Parkin further elevates cytosolic glutathione levels and protects against oxidative stress, characterising it as a critical tumour suppressor with anti-glycolytic and antioxidant capabilities. Clinical significance Parkinson’s disease PARK2 (OMIM *602544) is the parkin gene that may cause a form of autosomal recessive juvenile Parkinson disease (OMIM 600116) due to a mutation in the parkin protein. This form of genetic mutation may be one of the most common known genetic causes of early-onset Parkinson disease. In one study of patients with onset of Parkinson disease prior to age 40 (10% of all PD patients), 18% had parkin mutations, with 5% homozygous mutations. Patients with an autosomal recessive family history of parkinsonism are much more likely to carry parkin mutations if age at onset is less than 20 (80% vs. 28% with onset over age 40). Patients with parkin mutations (PARK2) do not have Lewy bodies. Such patients develop a syndrome that closely resembles the sporadic form of PD; however, they tend to develop symptoms at a much younger age. In humans, loss-of-function mutations in parkin PARK2 gene have been implicated in 50% of inherited and 15% of juvenile-onset sporadic forms of Parkinson’s disease (PD). While PD is traditionally regarded a late-onset neurodegenerative condition characterised by alpha-synuclein-enriched Lewy bodies, autosomal recessive PD due to parkin mutations is often early onset and lack the ubiquitinated protein deposits pathognomonic for sporadic PD. Parkin-mutant PD could also involve loss of noradrenergic neurons in the locus coeruleus alongside the hallmark degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc). However, its symptoms resembles those of idiopathic PD, with patients presenting with resting tremors, postural instability and bradykinesia. While mitochondria are essential for ATP generation in any eukaryotic cell, catecholaminergic neurons are particularly reliant on their proper function for clearance of reactive oxygen species produced by dopamine metabolism, and to supply high energy requirements of catecholamine synthesis. Their susceptibility to oxidative damage and metabolic stress render catecholaminergic neurons vulnerable to neurotoxicity associated with aberrant regulation of mitochondrial activity, as is postulated to occur in both inherited and idiopathic PD. For example, enhanced oxidative stress in neurons, skeletal muscle and platelets, corresponding with reduced activity of complex I in the electron transport chain were reported in PD patients, while deletions in the mitochondrial genome were found in the SNpc. In