Hereditary or primary lymphedema is associated with mutations in genes that encode for lymphatic endothelial markers; vascular endothelial growth factor-C (VEGFC) and its receptor (VEGFR), such as Fms-related receptor tyrosine kinase-4 (FLT4), SRY-box transcription factor 18 (SOX18), forkhead box C2 (FOXC2), and angiopoietin (ANGPT2) (Miaskowski et al., 2013; Brouillard et al., 2014; Leppanen et al., 2020). The gene discussed is SOX18; the disease is primary lymphedema.