A 50-year-old right-handed man was referred to the movement disorders clinic for evaluation of a rigid akinetic syndrome. Family history was pertinent for a progressive gait disorder with onset in mid-life in the patient’s father, brother, and paternal grandfather. Neurological exam showed pronounced bradyphrenia and generalized bradykinesia, with asymmetric rigidity and appendicular bradykinesia. There was no postural instability, eye movement abnormalities, cortical signs, or cognitive changes. Levodopa titration (up to 2,000 mg/day) led to marked improvement in parkinsonism, gait speed, and function. Testing for genetic forms of Parkinson disease was negative. CT head showed mineralization of both globus pallidus and right caudate. MRI showed increased susceptibility with corresponding T1 shortening about the bilateral lenticular nuclei, and right caudate head. Genetic testing showed pathogenic mutation of SLC20A2, confirming diagnosis of Primary Familial Brain Calcification. Over several years, the patient’s parkinsonism progressed, with development of motor fluctuations and generalized dyskinesias, while maintaining robust therapeutic response to levodopa. 

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Primary Familial Brain Calcification (PFBC) is most often inherited in an autosomal dominant pattern. Several genes have been implicated, including variants of SLC20A2, PDGFRB, and XPR1. Patients display movement disorders with varying presentations; Parkinsonism is most common.

The unique feature of this case is parkinsonism progression over time with development of motor fluctuations and dyskinesias while maintaining levodopa responsiveness. This is clinically indistinguishable from idiopathic Parkinson disease. This highlights the importance of obtaining a complete history, including family history, and brain imaging where appropriate. PFBC is a rare disorder and the efficacy of levodopa for its treatment is not widely studied. Levodopa responsiveness with development of dyskinesias has rarely been reported and not in conjunction with this mutation. Given that levodopa is highly effective in treating similar disorders of calcification, it appears to remain a viable symptomatic treatment for PFBC as well.