Systemic sclerosis (SSc) is a connective tissue disorder characterized by early generalized microangiopathy with disturbed angiogenesis. Endoglin gene (ENG) encodes a transmembrane glycoprotein which acts as an accessory receptor for the transforming growth factor-beta (TGF-beta) superfamily, and is crucial for maintaining vascular integrity. A 6-base insertion in intron 7 (6bINS) of ENG has been reported to be associated with microvascular disturbance.
Objectives: Our objective was to investigate the relationship between 6bINS and the vascular complication pulmonary arterial hypertension (PAH) in SSc in a French Caucasian population.
Methods: Two hundred eighty SSc cases containing 29/280 having PAH diagnosed by catheterism were compared with 140 patients with osteoarthritis. Genotyping was performed by polymerase-chain-reaction-based fluorescence and direct sequencing of genomic DNA.
Results: The polymorphism was in Hardy-Weinberg equilibrium. We observed a significant lower frequency of 6bINS allele in SSc patients with associated PAH compared with controls [10.3 vs 23.9%, P = 0.01; odds ratio (OR) 0.37, 95% confidence interval (CI) 0.15-0.89], and a trend in comparison with SSc patients without PAH (10.3 vs 20.3%, P = 0.05; OR: 0.45, 95% CI: 0.19-1.08). Genotypes carrying allele 6bINS were also less frequent in SSc patients with PAH than in controls (20.7 vs 42.9%, P = 0.02).
Conclusions: Thus the frequency of 6bINS differs between SSc patients with or without PAH, suggesting the implication of ENG in this devastating vascular complication of SSc.