Mutations of the DCX gene (Xp22.3) cause X-linked lissencephaly in males and 
double cortex syndrome (DCS) or subcortical band heterotopia (SBH) in females. 
SBH is characterized by bilateral bands of grey matter interposed in the white 
matter between the cortex and the lateral ventricles. The main clinical 
manifestation in patients with SBH is epilepsy, which may be partial or 
generalized and is intractable in approximately 65% of the patients. An 
association of periodic limb movements (PLMs) and SBH has not been documented 
previously. We describe a 2-year-old girl affected by SBH with epilepsy and 
periodic limb movements (PLMs), in whom a novel "de novo" missense substitution, 
Met1Val (M1V), was identified in the DCX gene. Physiopathological links between 
PLMs and SBH are discussed.