Melkersson-Rosenthal syndrome (MRS) is a rare, inherited syndrome that affects the nervous system and skin (a neurocutaneous syndrome). MRS may be characterized by three main features: recurrent facial nerve palsy, episodes of swelling of the face and lips, and fissuring of the tongue (formation of deep grooves). The majority of people with MRS only have one or two of these features, rather than all three. MRS is more common in females than in males. Inheritance of MRS is autosomal dominant, but a consistent genetic cause has not been found. It is possible that more than one gene is responsible for MRS, and/or that environmental "triggers" may contribute to causing the syndrome in some genetically predisposed individuals. In some cases, MRS may be associated with Crohn's disease or sarcoidosis. MRS is diagnosed based on the symptoms present and medical history, and a biopsy of the lips may be needed to confirm the diagnosis in some cases.