Genetics of infantile seizures with paroxysmal dyskinesia: the infantile convulsions and choreoathetosis (ICCA) and ICCA-related syndromes
- 1INSERM U925 & Service de Génétique Médicale, Université de Picardie Jules Verne, Amiens, France
- 2INSERM UMR910, Université de la Méditerranée, Marseille, France
- Dr P Szepetowski, Inserm UMR910, GEIA Group, Faculté de Médecine de la Timone, 27 Bd J Moulin, 13385 Marseille Cedex 5, France;
- Received 11 April 2008
- Revised 11 April 2008
- Accepted 9 June 2008
The relationship between paroxysmal movement disorders (PD: paroxysmal dyskinesia) and epilepsy continues to present a challenging problem. Attacks of PD and epileptic seizures have several characteristics in common: both are paroxysmal in nature with a tendency to spontaneous remission, and a subset of PD responds well to anticonvulsants. In 1997, description of the ICCA (infantile convulsions and choreoathetosis) syndrome and linkage to chromosome 16p12-q12 provided the first genetic evidence for common mechanisms shared by benign infantile seizures and PD. The chromosome 16 ICCA locus is by far the most frequently involved in such associations as well as in pure forms of benign infantile seizures. The ICCA region at the pericentromeric area of chromosome 16 shows complicated genomic architecture and the ICCA gene still remains unknown. Genetic studies focusing on PD with or without epilepsy have led to the identification of other genes linked to chromosomes 2q35 and 10q22. Alterations of ion channel and ion pump subunits could provide a simple, albeit probably non-unique, explanation for the pathophysiology of the link between epilepsy and PD. The aim of this review is to update genetic aspects of infantile epileptic seizures and PD and their association in the context of ICCA and ICCA related syndromes.
While this review was under editing process, two articles (Suls et al, Brain, Advance Access, published 2008 June 24th, PMID: 18577546; Weber et al, J Clin Invest, June 2008, vol 118, PMID: 18577546) reported on the mutations of the chromosome 1p34.2 SLC2A1 gene, encoding the glucose transporter GLUT1 (OMIM 138140), in families presenting with epilepsy associated with paroxysmal exertion induced dyskinesia. These results add to the complexity of the association of epilepsy with paroxysmal dyskinesia as some of the families reported in these articles also presented with hematological symptoms. They also bring novel insights into one of the possible mechanisms that may cause the association of epilepsy with paroxysmal dyskinesia, and provide a potential treatment option (ketogenic diet) at least for the forms that are linked to SLC2A1 mutations.
Funding: This work was supported in part by a grant from the Picardie county as well as by INSERM and by GIS/Institut des Maladies Rares.
Competing interests: None.