SLC2A1 and paroxysmal dyskinesia: No doubt this wide variation in clinical presentation contributed to the erroneous assignation of DYT9 (paroxysmal choreoathetosis with spasticity) and DYT18 (PED with or without epilepsy) as two separate conditions; it is now known that the causative gene in both cases was, in fact, SLC2A1 (Weber et al., 2011).