[The genetics of movement disorders--spinocerebellar degenerations].
BACKGROUND
Hereditary movement disorders include spinocerebellar disorders, a large and heterogeneous group of syndromes with ataxia or spasticity as the prominent symptom. In spite of the vast clinical and genetic heterogeneity, patterns of pathogenesis slowly emerge and help us understand these disorders.


METHODS
This review is based on personal experience and recent literature.


RESULTS
More than 20 types of hereditary spastic paraparesis have been reported. Dominant SPG4 and SPG3 with mutations in the spastin or the atlastin gene have been identified in many countries. The most prevalent type of recessive ataxia in Europe, Friedreich's ataxia, has become a model of integrated clinical-molecular-therapeutic research. More recessive ataxias (AOA1-2) have been described recently. More than 20 autosomal dominant ataxias have been reported, with 12 identified genes including the episodic ataxias, and 9 mapped. SCA7 appears to be the most frequent type in some Nordic countries.


CONCLUSIONS
A striking feature of many of these diseases is the involvement of very different genes for similar phenotypes. Conversely, very heterogeneous phenotypes are due to single-gene defects. Recently there has been considerable progress in the clinical description of movement disorders and the understanding of their genetic basis. Possible therapies are emerging.
Tallaksen
Chantal M E
CM
Nevrologisk avdeling, Ullevål universitetssykehus, 0407 Oslo. chantal.tallaksen@ulleval.no
Dietrichs
Espen
E
D005838:Genotype; D006801:Humans; D009069:Movement Disorders / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics* / Q000628:therapy; D009664:Norway / Q000453:epidemiology; D020336:Paraparesis, Spastic / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics / Q000628:therapy; D010641:Phenotype; D013132:Spinocerebellar Degenerations / Q000175:diagnosis / Q000453:epidemiology / Q000235:genetics* / Q000628:therapy