Phenotypic variability of PINK1 expression. 12 Years' clinical follow-up of two Italian families

Background: Mutations in the PINK1 gene are the second most frequent cause of autosomal recessive early-onset parkinsonism. Methods: We evaluated five affected PINK1 homozygous and 14 heterozygous mutation carriers from two large Italian families over a 12-year follow-up period. Motor, nonmotor, cognitive, psychiatric, and behavioral profiles were systematically assessed. Four homozygotes and eight heterozygotes underwent magnetic resonance imaging. Results: All homozygotes showed a mild progression of motor signs and a persistent excellent response to levodopa. All but one patient complained of nonmotor symptoms and sleep impairment. Three presented impulse control disorders and two anxiety and apathy. All obtained abnormal scores at Montreal Cognitive Assessment (MoCA) and in tests sensitive to frontal functions; one presented a global cognitive impairment. Three heterozygotes showed motor signs and were diagnosed as possibly affected. They had nonmotor symptoms and cognitive impairment, and two of them showed mild bilateral temporal atrophy. Five unaffected heterozygotes reported abnormal scores at MoCA and low performances at tests sensitive to frontal functions. Conclusion: We expanded the phenotypic profile of PINK1-related parkinsonism, including psychiatric and cognitive features as part of clinical presentation.