Investigation of rs2274924 and rs3750425 polymorphisms in TRPM6 gene in the etiology of idiopathic pulmonary arterial hypertension

Idiopathic pulmonary arterial hypertension (IPAH) is a subgroup of pulmonary hypertension due to increased vascular resistance of unknown origin. Magnesium has been shown to play an active role in vascular remodeling, blood pressure regulation and hypertension in the human body. Studies have shown that the ion channel of Transient receptor potential melastatin 6 (TRPM6) is sensitive to magnesium (Mg+2) ion, is expressed in lung and endothelial cells and is associated with hypomagnesemia. As a result of the literature review, these two variants were selected because there are many studies showing that rs2274924 and rs3750425 variants of TRPM6 gene are associated with Mg+2. In this context, the present study aimed to analyze the rs2274924 and rs3750425 variants of TRPM6 gene and promoter methylation levels in IPAH patients compared to a healthy control group. In line with this purpose, our study was conducted with 198 patients diagnosed with IPAH and 198 healthy control subjects obtained from the Cardiology Clinic of Fırat University Faculty of Medicine. DNA was isolated from the blood samples obtained from the patient and control groups in our Medical Biology department laboratories and the related polymorphisms in TRPM6 gene were analyzed using Real-time PCR Taq -Man genotyping method. TRPM6 gene promoter methylation analysis was determined by quantitative qRT-PCR analysis in the presence of methylation specific primers after bisulfite modification of DNA. In terms of rs2274924 genotype distributions and allele frequencies, no significant result was observed between the groups (p>0.05). In terms of rs3750425 genotype distributions, CT heterozygous genotype was observed in 40% of the patient group and 28% of the control group and CT heterozygous genotype was statistically significant in the patient group (p=0.036). However, this significance level could not be reached although a borderline significance value (p=0.073) was obtained in terms of allele frequencies. When the patient subgroups were analyzed in terms of genotype distributions, there was a significant difference between the IPAH group and the control group for the rs3750425 allele (p=0.03). Methylation analysis revealed no significant difference between the patient and control groups in terms of methylation. As a result of haplotype analysis, it was found that TT/CT haplotype increased significantly in the patient group in support of our genotype findings in terms of rs2274924/rs3750425 haplotypes. Although no evidence supporting an association between the rs2274924 polymorphism of the TRPM6 gene and IPAH was obtained in the present study, preliminary evidence supporting that the CT genotype of the rs3750425 polymorphism may be a risk factor for predisposition to IPAH was obtained. This suggests that the variant may be altered in relation to Mg+2 intake in terms of IPAH risk. Further studies are needed to confirm these results and to understand the rs3750425 variant of the TRPM6 gene in relation to IPAH and Mg+2. Key Words: Pulmonary hypertension, TRPM6, IPAH, polymorphism