Swelling of the extremities (lymphoedema) due to underlying abnormalities of the lymphatic system has many causes but can be genetic. We describe 20 patients with a newly defined clinical entity called WILD syndrome (acronym from Warts, Immunodeficiency and Lymphatic Dysplasia). They presented with asymmetrical lymphoedema affecting different body regions including internal organs. Low immunity was characterised by low blood lymphocytes and multiple warts which risk malignant transformation. We hypothesise that the genetic fault is not inherited and affects only certain tissue cells (post-zygotic mosaic mutation). (By Professor Sahar Mansour, https://jmg.bmj.com/content/early/2021/12/15/jmedgenet-2021-107820 )