GDNF and Constipation: In a study reporting a large family with five HSCR and two constipation cases, variants in four genes: the lipopolysaccharide-responsive and beige-like anchor protein (LRBA), RET, the RET ligand glial-derived neurotrophic factor (GDNF), Indian hedgehog (IHH), and a mediator of IHH signaling GLI family zinc finger 3 (GLI3), were identified.