English: St. George's classification algorithm for primary lymphatic anomalies. The five main groupings (colour coded) wit their various clinical subtypes of disease. Primary lymphoedema is the major clinical features in the green, pink, and purple sections. Text in red indicates the suggested genetic test and/or differential diagnosis for the subgroup, however, the indicated genes do not explain the cause of disease in all patients in each grouping. For example, only 70% of Milroy disease patients are explained by mutations in FLT4/VEGFR3. FH, family history; +ve, positive; -ve, negative. For more information see Connell et al 2013 in Clinical Genetics (PMID: 23621851).