Inherited Myoclonus-dystonia syndrome: narrowing the 7q21-q31 locus in German families.

Genetic studies were performed in four German families with autosomal dominant myodonus-dystonia syndrome. Mutations in the D2 dopamine receptor gene, which have been implicated in this disorder, were excluded in all four families by linkage analysis and direct sequencing. All four families supported linkage to the second reported locus on chromosome 7q21 with a combined maximum multipoint lod score of 5.99. The observation of key recombinations in one family refined the disease locus to a 7.2 cM region flanked by the markers D7S652 and D7S2480.