Early Ataxia and Subsequent Parkinsonism: PLA2G6 Mutations Cause a Continuum Rather Than Three Discrete Phenotypes.

-associated neurodegeneration comprises a heterogeneous spectrum of age-related phenotypes, with three forms classically recognized, including infantile neuroaxonal dystrophy (INAD) with onset in infancy, atypical neuroaxonal dystrophy (atypical NAD) with onset in childhood, and dystonia-parkinsonism (PARK14) with onset in early adulthood. We describe 3 cases that challenge this view, discuss the related literature, and suggest that mutations cause a phenotypic continuum rather than three discrete phenotypes, further ensuing clinical implications.