The analysis of etiologies suggested a predominant association of chorea with a subset of genes or CNV involved in post-synaptic signaling (e.g., GNAO1, GNB1, FOXG1, MEF2C, CLN2, MeCP2 duplication) and a high quote of the pathogenic gene or chromosomal variants associated with neurodegenerative and metabolic diseases among patients presenting with myoclonus and parkinsonism. This evidence concerns the gene MECP2 and Parkinson disease.