CCBE1 (Collagen And Calcium Binding EGF Domains 1): CCBE1 is a gene essential for lymphangiogenesis, the formation of lymphatic vessels. It regulates vascular endothelial growth factor C (VEGF-C), a key factor in lymphatic system development. Mutations in CCBE1 can cause Hennekam syndrome, a rare disorder marked by lymphedema, lymphangiectasia, and intellectual disability.