Abstracts from the Fourth International Symposium on Neuroacanthocytosis
July 1-2, 2008
London and Oxford
Chairs: Prof. Kailash Bhatia, MD, FRCP, Institute of Neurology, University College London; Prof. Anthony P. Monaco, MD, PhD, Wellcome Trust Centre for Human Genetics, University of Oxford
Organizers: Antonio Velayos-Baeza, PhD; Susanne Schneider, MD; Glenn Irvine
1-1 Introduction: movement disorder phenomenology
Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, Queen Square, London WC1N 3BG, UK
Chorea is a hyperkinetic movement disorder characterized by involuntary movements which flit and flow unpredictably from one body part to another. Dystonia is characterized by involuntary muscle spasms resulting in writhing movements and abnormal body postures. Chorea and dystonia are the main movement disorders exhibited by patients with neuroacanthocytosis, although tics and parkinsonism may also be present. The differential diagnosis in a patient with familial adult-onset chorea entails Huntington's disease (HD), which is caused by a triplet repeat expansion in the IT15 gene (also known as huntingtin) and which accounts for about 90% of cases of chorea of genetic etiology, as well as other distinct genetic disorders which can present with a clinical picture indistinguishable from HD. These disorders are termed HD-like (HDL) syndromes. So far, four such conditions have been recognized, including disorders attributable to mutations in the prion protein gene (HDL1), the junctophilin 3 gene (HDL2) and the gene encoding the TATA box-binding protein (HDL4), and a single family with a recessively inherited HD phenocopy, the genetic basis of which is currently unknown (HDL3). These disorders, however, account for only a small proportion of cases with the HD phenotype but a negative genetic test for HD, and the list of HDL genes and conditions is set to grow.