STXBP1 and lissencephaly spectrum disorders: Previous studies on STXBP1 variants have shown diverging results.11,12,38,39 Five out of six children with lissencephaly and causative variants in PAFAH1B1 in our cohort showed KD response at 3 and 6 months, and at 2-year follow-up, one was still a responder.