A Novel Likely Pathogenic Variant in NOTCH1 Associated With Primary Lymphedema

Lymphedema is a chronic condition characterized by the accumulation of lymphatic fluid in interstitial and fibro-adipose tissues. Primary lymphedema that arises from intrinsic defects in the lymphatic system is a rare form of lymphedema with a variable age of onset and heterogeneous presentation. Although a number of genetic variants have been identified and matched to corresponding phenotypes, a genetic cause for lymphedema is found in less than 30% of individuals with primary lymphedema. Recently, Michelini et al proposed NOTCH1 as a candidate gene for primary lymphedema, having identified missense variants in NOTCH1 in 7 of 235 patients with primary lymphedema for whom no causative gene had previously been identified. We report the case of a young female who developed bilateral primary lower limb lymphedema and on genetic testing was found to have a previously unreported heterozygous frameshift variant in the NOTCH1 gene predicting loss of function.