Familial writer’s cramp: a clinical clue for inherited coenzyme Q(10) deficiency

The spectrum of coenzyme Q(10) (CoQ(10)) deficiency syndromes comprises a variety of disorders, including a form of autosomal recessive cerebellar ataxia (ARCA2) caused by mutations in the AarF domain–containing kinase 3 gene (ADCK3). Due to the potential response to CoQ(10) supplementation, a timely diagnosis is crucial. Herein, we describe two siblings with a novel homozygous ADCK3 variant and an unusual presentation consisting of isolated writer’s cramp with adult-onset. Cerebellar ataxia developed later in the disease course and remained stable during the follow-up. This report highlights that ARCA2 should be considered in the differential diagnosis of familial writer’s cramp. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s10048-020-00624-3) contains supplementary material, which is available to authorized users.