SGCE and Myoclonus: Classical myoclonus-dystonia is caused by heterozygous mutations in SGCE, and the condition can be inherited in an autosomal dominant fashion but with greatly reduced penetrance in the case of maternal transmission owing to maternal imprinting of SGCE. However, both myoclonus and dystonia have also been previously described in cases of ADCY5-related dyskinesia (Table 1), suggesting that this gene should also be considered in such cases.