Objective: Endothelin-1 plays an important role in the pathogenesis of severe pulmonary hypertension. The + 139 'A', adenine insertion variant in 5'UTR of edn1 gene has been reported to be associated with increased expression of Endothelin-1 in vitro. The aim of present study was to explore the association of this variant with the circulating levels of Endothelin-1 in vivo using archived DNA and plasma samples from 38 paediatric congenital heart disease (cyanotic and acyanotic) patients with severe pulmonary hypertension.
Results: The plasma Endothelin-1 levels were highly varied ranging from 1.63 to75.16 pg/ml. The + 139 'A' insertion variant in 5'UTR of edn1 was seen in 8 out of 38 cases with only one acyanotic sample demonstrating homozygosity of inserted 'A' allele at + 139 site (4A/4A genotype). The plasma Endothelin-1 levels in children with homozygous variant 3A/3A genotype were comparable in cyanotic and acyanotic groups. Lone 4A/4A acyanotic sample had ET-1 levels similar to the median value of ET-1 associated with 3A/3A genotype and was absent in cyanotic group presumably due to deleterious higher ET-1 levels. The discussed observations, limited by the small sample size, are suggestive of homozygous adenine insertion variant posing a risk in cyanotic babies with Severe Pulmonary Hypertension.
Keywords: 5′Untranslated region (5′UTR); Acyanotic; Allele; Congenital heart disease; Cyanotic; Endothelin-1; Haplotype; Severe pulmonary hypertension; Single nucleotide polymorphisms; Upstream regulatory element.