Parkinsonism in Childhood, a Clue to Autosomal Recessive ADCY5 ‐Related Movement Disorder?

Background Advances in genetic testing have allowed for refined phenotypic categorization of pediatric‐onset genetic movement disorders. ADCY5 ‐related movement disorder is among this group of conditions for which we have begun to better understand a genotype–phenotype correlation. Cases This case series details the clinical course of three biological brothers with autosomal recessively inherited biallelic variants in the ADCY5 gene. Each brother demonstrates a varied severity and combination of mixed movement disorder phenomenology, including parkinsonism, dystonia, and myoclonus exemplified in videos. Conclusion The phenotype classically associated with ADCY5 ‐related movement disorders, particularly when inherited recessively, should be expanded to include a wider spectrum of severity as well as early‐onset parkinsonism. Adjusting the classically recognized phenotype in this way will help to prevent delays to genetic testing, diagnosis, and treatment while informing prognostic counseling.