[Does the ataxo-choreic form of DRPLA exist in Europe? Search of mutation in 120 families].

Dentatorubral-pallidoluysian atrophy (DRPLA) is an autosomal dominant neurodegenerative disorder characterized by a degeneration of cerebellar and pallidal efferents, more frequent in Japan. Isolated cases are also encountered. Patients present with variable combination of signs including myoclonus, ataxia, epilepsy, choreoathetosis and dementia, with onset from childhood to the seventh decade. Clinically, DRPLA may be undistinguishable from other genetic disorders, in particular Huntington's disease or the spinocerebellar ataxias. The genetic basis of the inherited form of DRPLA is an expansion to more than 49 repeats of an unstable trinucleotide (CAG) in the DRPLA gene on the short arm of chromosome 12. We determined the frequency of this mutation in patients with the DRPLA phenotype. One hundred and seventeen patients with cerebellar ataxia, from 94 families and 23 isolated cases, as well as 3 patients from families with undiagnosed autosomal dominant neurodegenerative disorders were investigated for the presence of the expanded sequence. None of the patients carried this mutation. This finding suggests that DRPLA is rare in the French population. The search for the DRPLA mutation is justified in patients with the DRPLA phenotype, however, since genetic counselling is often requested and neither clinical, nor neuropathological examinations permit a definite diagnosis of the underlying disease.