Evaluation of HHIP Polymorphisms and their relationship with chronic obstructive pulmonary disease phenotypes

Abstract

Purpose: We aimed to correlate three polymorphisms of the Hedgehog Interacting Protein (HHIP) gene with the three main phenotypes of the chronic obstructive pulmonary disease (frequent exacerbator (FE), asthma/COPD overlap (ACO), and emphysema with hyperinflation). Patients and methods: A cross-sectional study was carried out in the Department of Pulmonology at the Rio de Janeiro State University from February 2015 to July 2018. A total of 81 patients diagnosed with COPD according to the criteria of the Global Initiative for Chronic Obstructive Lung Disease (GOLD) were enrolled. The subjects were divided into three distinct groups according to their phenotypes (FE, ACO and emphysema-hyperinflation). Three polymorphisms of the HHIP gene that are often reported as allegedly involved in the pathogenesis of COPD were analysed: rs1828591, rs13118928, and rs6537296. Real-time PCR - TAQMAN SNP Genotyping Assay was performed. The statistical analysis was carried out with the SPSS program with a multivariate analysis with a 95% confidence interval. Results: An increase in the frequency of the A allele of the rs13118928 HHIP gene polymorphism was observed in the group of subjects with COPD and emphysema-hyperinflation phenotype when compared with those in the FE phenotype (p=0.019) and subjects with ACO (p=0.04). However, the subjects with emphysema-hyperinflation phenotype presented more often the A allele (p=0.04). The genotypic analysis confirmed the difference between the emphysema-hyperinflation and ACO phenotypes, with a higher prevalence of the AA genotype in the emphysema-hyperinflation group (p=0.04). The ACO and FE phenotype subjects showed no difference in these polymorphisms. No difference was found in the frequency of the polymorphisms rs1828591 (p= 0.552) and rs6537296 (p=0.296) in the three phenotypes evaluated. Conclusion: The presence of the A allele in the rs13118928 polymorphism of the HHIP gene may be related to the emphysema-hyperinflation phenotype.