Clinical differentiation of genetically proven benign hereditary chorea and myoclonus-dystonia

Abstract

Because of clinical similarities, benign hereditary chorea and myoclonus-dystonia (DYT11) might be confused. No systematic comparisons of genetically proven cases with thyroid transcription factor-1 (TITF-1) and epsilon-sarcoglycan (SGCE) mutations have been performed to date. Three index patients and one index patients' daughter underwent genetic analysis of the TITF-1 and the SGCE gene. The movement disorders of all patients were assessed by video review. A new splicing mutation (376-2A>C) of the TITF-1 gene was detected in a mother and her daughter. Two additional patients carried a de novo SGCE nonsense mutation in exon 3 (R97X) and a novel SGCE missense mutation in exon 6 (G227V). Both TITF-1 mutation carriers presented with infancy-onset, nonprogressive chorea, which responded to alcohol intake. In addition, dystonia of the neck and trunk as well as fleeting jerky movements of the distal limbs could be observed. The mutually exclusive appearance of lightning-like myoclonic jerks triggered by action in SGCE mutation carriers and of continuous chorea of all limbs in TITF-1 mutation carriers phenotypically discriminated both genetic disorders. TITF-1 mutations should be considered in choreiform movement disorders with onset in infancy even in the presence of dystonia and myoclonic jerks.