A Novel Splice-Site Mutation in VEGFC Is Associated with Congenital Primary Lymphoedema of Gordon

Abstract

Lymphedema is characterized by chronic swelling of any body part caused by malfunctioning or obstruction in the lymphatic system. Primary lymphedema is often considered genetic in origin. VEGFC, which is a gene encoding the ligand for the vascular endothelial growth factor receptor 3 (VEGFR3/FLT4) and important for lymph vessel development during lymphangiogenesis, has been associated with a specific subtype of primary lymphedema. Through Sanger sequencing of a proband with bilateral congenital pedal edema resembling Milroy disease, we identified a novel mutation (NM_005429.2; c.361+5G>A) in VEGFC. The mutation induced skipping of exon 2 of VEGFC resulting in a frameshift and the introduction of a premature stop codon (p.Ala50ValfsTer18). The mutation leads to a loss of the entire VEGF-homology domain and the C-terminus. Expression of this Vegfc variant in the zebrafish floorplate showed that the splice-site variant significantly reduces the biological activity of the protein. Our findings confirm that the splice-site variant, c.361+5G>A, causes the primary lymphedema phenotype in the proband. We examine the mutations and clinical phenotypes of the previously reported cases to review the current knowledge in this area.

Development and physiological functions of the lymphatic system: insights from human genetic studies of primary lymphedema

“…In nearly all cases reported, swelling is confined to the lower limbs, often just the dorsum of the feet. One case has shown intermittent hand swelling (275). The lymphedema usually presents at birth and there are no other major pathological features, apart from some patients who present with prominent, varicose veins and hydrocele.…”

“…So far five families have been reported, all of whom had heterozygous loss-of-function mutations (frameshift and splicing variants) (17, 106,134,275). All mutations are predicted to cause truncation of the VEGFC protein, with consequential complete or partial loss of the VEGF homology domain (VHD) and C-terminal propeptide.…”

“…Disease mechanism: VEGFC function is conserved through evolution as vegfc is also required for lymphatic vasculature development in zebrafish (213). Experimental work showed that the injection of wildtype human pro-VEGFC into zebrafish can stimulate lymphatic vessel sprouting, but when mutant human pro-VEGFC (totally or partially lacking the VHD and the C-terminus, as found in lymphedema patients) was injected, the truncated protein failed to induce lymphatic vessel sprouting (134,275). Zebrafish mutants lacking the C-terminal domain also failed to develop lymphatics, due to the inefficient secretion of VEGFC, which indicates that the presence of the pro-VEGFC C-terminus is essential for efficient secretion of VEGFC during lymphatic development (381).…”

Update and audit of the St George’s classification algorithm of primary lymphatic anomalies: a clinical and molecular approach to diagnosis

“…Pathogenic variants in VEGFC, the ligand for VEGFR3, have also been identified in association with congenital primary lymphoedema of Gordon (OMIM 615907), also affecting the lower limbs. [23][24][25][26] The congenital category represents 21% (n=47) of the patients seen in 2016 (figure 2, pie chart) compared with 24% in 2010. 8 A pathogenic variant was identified in 19 of the 47 (40%) patients genetically tested in this category.…”

Cellular Origins of the Lymphatic Endothelium: Implications for Cancer Lymphangiogenesis

“…Notably, during the past two decades specific mutations on VEGFC ( Gordon et al, 2013 ; Balboa-Beltran et al, 2014 ; Fastré et al, 2018 ; Nadarajah et al, 2018 ), VEGFR3 ( Ferrell, 1998 ; Irrthum et al, 2000 ; Karkkainen et al, 2000 ; Evans, 2003 ; Brice, 2005 ; Daniel-Spiegel et al, 2005 ; Mizuno et al, 2005 ; Butler et al, 2007 ; Ghalamkarpour et al, 2006 , 2009 ; Dai et al, 2018 ) and additional lymphangiogenesis-related genes, have been found to be strongly associated to the onset of primary lymphedema (reviewed in Oliver et al, 2020 ).…”