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RAPID-ONSET DYSTONIA-PARKINSONISM IN A CHILD WITH A NOVEL ATP1A3 GENE MUTATION

Rapid-onset dystonia-parkinsonism (RDP) has been linked to mutations in the ATP1A3 gene.1 We present a case with onset of symptoms at age 4 years, with previously undescribed clinical features including episodes of flaccidity and lack of motion for hours, later evolving into episodes of stiffness. Sequencing of ATP1A3 revealed a novel heterozygous nucleotide substitution c.2767G>A, resulting in an aspartic acid (D) to asparagine (N) substitution at amino acid position 923. This mutation is predicted to impair the activity of the neuron-specific α3 subunit of Na,K-ATPase.

Diagnostic criteria for RDP include abrupt onset of dystonia with features of parkinsonism over a few minutes to 30 days, rostrocaudal progression, and prominent bulbar findings.2 Antecedent symptoms such as mild dystonia involving hands and arms may precede acute onset. Primary onset of symptoms is frequently associated with physical or emotional stress. Patients do not respond to l-dopa or dopamine agonists.3 The parkinsonian symptoms are limited to bradykinesia and truncal instability. The most common age at onset of symptoms is young adulthood.2 Onset at age 4 years was reported by Pittock et al.4 The described 38-year-old man had intermittent episodes of dysarthria and hemidystonia associated with stress and anxiety from an early age, lasting from hours to weeks. At baseline, he had only mild dysarthria and slight increase in tone in the left upper …