CCBE1 and Hennekam syndrome: CCBE1 is a secreted molecule involved in lymphatic vasculature development and mutations in CCBE1 were identified in patients with Hennekam syndrome, a rare autosomal recessive disorder of lymphatic development leading to primary LD (Bonet et al, 2022; Hogan et al, 2009; Kunnapuu et al, 2021; Van Balkom et al, 2002).