5′UTR Repeat Polymorphisms of the BMPR2 gene in Children with Pulmonary Hypertension associated with Congenital Heart Disease

Abstract

The mutations of bone morphogenetic protein receptor type 2 (BMPR2) in patients with idiopathic pulmonary hypertension has been well defined. We investigated the occurrence of BMPR2 mutation and genetic polymorphisms in children with pulmonary hypertension associated with congenital heart disease (aPH/CHD) and correlated with the pulmonary haemodynamic and vasoreactivity. BMPR2 mutation/polymorphisms were determined in 30 aPH/CHD children. All children underwent cardiac catheterisation to obtain baseline haemodynamic data. The 5'UTR containing promoter region and all the exons [1-13] of BMPR2 gene were genotyped for possible genetic variants that may be related to the aPH/CHD. None of our 30 patients (median-age 90 months) with aPH/CHD (mean PAP 48±17mmHg, PVR 6.7±4.2WUm(2)) has had any BMPR2 mutation. Fifteen of them had single nucleotide polymorphism, rs1061157 and/or 5'UTR-polymorphism, specifically GGC repeat variant in seven patients; AGC repeat variant in one patient; and nine base pairs duplication (CTTCTTCGG) in one patient. The GGC repeat ≥13 was found in three out of six of children with aPH/CHD with normal PVR vs. two out of 24 children with aPH/CHD with high PVR. The odd ratio between these two subgroups of aPH/CHD is 0.09 (95% CI 0.02-0.34). In our cohort, there was no BMPR2 mutation in children with aPH/CHD while nine out of 30 of them have 5'UTR repeat polymorphisms. Our data suggests the occurrence of GGC repeat ≥13 at the 5'UTR region may have some protective effect towards pulmonary vasculopathy in children who have been exposed to high pulmonary blood flow due to CHD.