Genetic atypical Parkinson's disease (PD) describes monogenic forms of PD that resemble idiopathic PD but feature prominent atypical clinical signs and symptoms and can be sub-grouped into i) atypical monogenic forms caused by mutations in the ATP13A2, DNAJC6, FBXO7, SYNJ1, VPS13C, and DCTN genes; ii) monogenic PD more closely resembling idiopathic PD, but associated with atypical features in at least a subset of cases (SNCA-, LRRK2-, VPS35-, Parkin-, PINK1-, and DJ-1-linked PD; iii) carriers of mutations in genes that are usually associated with other movement disorders but may present with parkinsonism, such as dopa-responsive dystonia.
Mutations in the SYNJ1 gene have been associated with early-onset of atypical Parkinson's disease or severe neurodegeneration with intractable seizures.
This is the first report of mutation in the C-terminal domain of Synaptojanin 1 protein causing mild juvenile PD with generalized seizures, cognitive impairment, and good respond to levodopa treatment.