The smallest deleted region of overlap in these previously described patients spans 1.7 Mb, containing DLL1, C6orf70 (ERMARD), PHF10, and THBS2. Based on our findings, the newly defined smallest region of overlap excludes PHF10 and THBS2. Conti et al. [54] showed data suggesting that C6orf70, also termed ERMARD (ER membrane-associated RNA degradation), plays a major role in the control of neuronal migration, and its haploinsufficiency or mutation causes periventricular nodular heterotopia. Here, DLL1 is linked to periventricular nodular heterotopia.