autonomic nervous system disorder harlequin syndrome https://rarediseases.info.nih.gov/diseases/8610/harlequin-syndrome https://www.malacards.org/card/harlequin_syndrome unilateral loss of facial flushing and sweating with contralateral anhidrosis MONDO:0016040 SCTID:14070001000004105 Orphanet:199282 GARD:0008610 sudden onset of unilateral flushing and sweating ICD9:705.89 MESH:C535634 UMLS:C2029348 Harlequin syndrome (HSD) is an autonomic disorder occurring at any age and characterized by unilateral flushing and sweating, involving the face and sometimes arm and chest, in condition of thermal, exercise or emotional stress without sympathetic ocular manifestations. However, tonic pupils, parasympathetic oculomotor lesion and pre- or postganglionic sudomotor sympathetic deficit can rarely occur. progressive isolated segmental anhidrosis MEDGEN:384475