In 90% of patients with choreatic movement disorder of genetic origin, a pathogenic CAG triplet repeat expansion in the HTT gene can be detected. For the remaining 10% with no evidence of a pathological HTT-CAG triplet repeat expansion, a differential diagnosis of “chorea-Huntington-like disorders”, clinically difficult or impossible to differentiate, can be clarified by comprehensive gene panel testing. For some of the listed genes, the presence of a repeat expansion is clarified by PCR and subsequent capillary electrophoresis (fragment length analysis).
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