English: Primary lymphedema is caused by an underlying genetic defect that compromises lymphatic function leading to localized lymph retention and swelling in any part of the body. The use of rigorous phenotyping, including imaging, has led to the development of a classification algorithm used to categorize lymphedema patients. Together with genotyping, through genetic studies and Next Generation Sequencing, several causal genes have been identified demonstrating that primary lymphedema is a complex heterogeneous condition. Animal and cellular models continue to be key in the discovery of pathogenic disease mechanisms. Using genotypes hitherto identified, this review will give a collective insight into the genes critical for the development and maintenance of the lymphatic system, concentrating our focus on the genetic variants associated with lymphedema and other lymphatic abnormalities as well as the clinical phenotypes and physiological mechanisms. Multidisciplinary research efforts have led to improved diagnostics and understanding of lymphatic physiology and will hopefully soon lead to the much-needed new treatments.