The high concordance rate of migraine in monozygotic twin pairs has long been recognised. In the current study, we present a monozygotic twin pair discordant for familial hemiplegic migraine (FHM).

Chromosomal aberrations are rare but known causes of movement disorders, presenting with broad phenotypes in which dystonia may be predominant. During the investigation of such cases, chromosomal studies are not often considered as a first approach. In this article, the authors describe a family affected by a generalized form of dystonia, evolving from a focal phenotype, for which a new X chromosome large duplication was found to be the likely causative, therefore highlighting the role of such studies when facing complex movement disorders.