Rare Movement Disorders-An Approach for Clinicians.

Rare genetic movement disorders usually manifest early in life with dystonia, parkinsonism, chorea, or a combination thereof. These are often associated with neurodevelopmental delay, intellectual disability, speech problems, retinal abnormalities, seizures, ataxia, spasticity, or systemic features. Due to their vast number and pheno-genotypic heterogeneity, the diagnosis of these disorders can be challenging. However, recognising their core motor phenomenology as well as clinical, laboratory, and neuroradiological clues can expedite appropriate diagnostic workup, molecular diagnosis, and adequate treatment. In this review, we outline diagnostic clues to rare movement disorders (RMDs), focusing on those that present mainly with dystonia, parkinsonism, or paroxysmal dyskinesia due to genetic causes. Additionally, we provide a decision tree approach linking clinical, genetic, and imaging testing. Finally, we highlight selected RMDs that should not be missed, as they possess established treatments that can hinder their progression, prevent irreversible or life-threatening sequelae and, in certain cases, lead to complete symptom remission.