Background:RAR-related Orphan Receptor C (RORC) is a DNA-binding transcription factor and the key transcription factor responsible for differentiation of T helper 17 cells. TheRORCgene plays a role in lymphoid organogenesis, thymopoiesis, and lymph node organogenesis. The aim of our study was to determine the possible role ofRORCin the development of lymphatic system malformations by combining data from the scientific literature and next-generation sequencing ofRORCin lymphedema patients negative for known causative genes. Methods and Results:We sequencedRORCin 235 lymphedema patients negative for known lymphedema-associated genes. We found two probands carrying nonsenseRORCvariants. Conclusions:We show thatRORCis important for normal function of the lymphatic system and that a rare variant with a possible causative effect may imply predisposition for lymphedema.