The tumor necrosis factor α (-308 A/G) polymorphism is associated with cystic fibrosis in Mexican patients

Genetic Modifying Factors of Cystic Fibrosis Phenotype: A Challenge for Modern Medicine

Cystic fibrosis (CF) is a monogenic autosomal recessive disease caused by cystic fibrosis transmembrane conductance regulator (CFTR) gene mutations. CF is characterized by a high phenotypic variability present even in patients with the same genotype. This is due to the intervention of modifier genes that interact with both the CFTR gene and environmental factors. The purpose of this review is to highlight the role of non-CFTR genetic factors (modifier genes) that contribute to phenotypic variability in CF. We analyzed literature data starting with candidate gene studies and continuing with extensive studies, such as genome-wide association studies (GWAS) and whole exome sequencing (WES). The results of both types of studies revealed that the number of modifier genes in CF patients is impressive. Their identification offers a new perspective on the pathophysiological mechanisms of the disease, paving the way for the understanding of other genetic disorders. In conclusion, in the future, genetic analysis, such as GWAS and WES, should be performed routinely. A challenge for future research is to integrate their results in the process of developing new classes of drugs, with a goal to improve the prognosis, increase life expectancy, and enhance quality of life among CF patients.

Steroid 5 alpha-reductase 2 enzyme variants, biomass exposure and tobacco use in Mexican patients with prostate cancer

The presence of the genetic variants of the steroid 5-alpha reductase 2 enzyme, which is encoded by the SRD5A2 gene, has been associated with an increased risk of developing prostate cancer among certain ethnic groups. However, these molecular studies have not been conducted on the Mexican population. The analysis of the genetic variants, rs9282858 and rs523349, was performed in 101 males with prostate cancer and 100 healthy controls classified as males without prostate abnormalities (n=60) and males with benign prostatic hyperplasia (n=40), to identify a probable association with this cancer type in the Northeast Mexican population. An association was identified between prostate cancer and biomass exposure [P=0.012; odds ratio (OR), 2.89; confidence interval (CI)=1.21-6.88] and tobacco use (P=0.028; OR=1.88; CI=1.07-3.31), while no association was observed between cancer development and the rs9282858 variant, or between a protective effect and the rs523349 variant. Notably, an association was identified between rs523349 and biomass exposure (P=0.013, OR=3.17; CI=1.23-8.17 for the G risk allele, and OR=0.32, CI=0.12-0.81 for the C protective allele) using the dominant genetic model. To the best of our knowledge, the present study was the first of its type to investigate the Mexican population with prostate cancer.

TNFα -857 C/T and TNFR2 +587 T/G polymorphisms are associated with cystic fibrosis in Iranian patients

Identification of modifier genes influencing phenotype of cystic fibrosis (CF) patients has become a challenge in CF pathophysiology, prognostic estimations and development of new therapeutic strategies. The aim of this study was to explore the association between four genetic polymorphisms of three modifier genes with CF, by comparing their alleles, genotypes and haplotype frequencies in patients and controls. In this favor, two regulatory polymorphic loci in TNFα promoter (-857C/T, rs1799724 and -238A/G, rs361525) and two functional polymorphic loci in TNFR1 (+36A/G, rs767455) and TNFR2 (+587T/G, rs1061622) were genotyped in 70 patients and 79 controls, using PCR-RFLP. Clinical pulmonary data were also recorded from all studied patients. Results indicated that an association was observed between both T allele and CT/TT genotypes of TNFα (P = 0.0005, OR = 7.06, 95% CI = 3.71-13.45) with CF under dominant model of inheritance. GG genotype of TNFR2 +587 (P = 0.0005, OR = 4.92, 95%CI = 2.34-10.34) was significantly associated with CF using recessive model. Consistently, more severe pulmonary disorder was found for patients carrying either T dominant allele of TNFα -857 or GG genotype of TNFR2 +587 polymorphic sites. Despite an association of A-T and G-T haplotypes with CF, no significant association was found between these haplotypes and clinical parameters of CF. Overall, TNFα -857 T allele and GG genotype of TNFR2 +587 were more frequent in CF patients compared to healthy controls and hence, they showed an association with CF and severe pulmonary phenotype in Iranian patients.

Influence of SNPs in Genes that Modulate Lung Disease Severity in a Group of Mexican Patients with Cystic Fibrosis

BACKGROUND

The variation in cystic fibrosis (CF) lung disease not always is explained by the CFTR genotype, so it has become apparent that modifier genes must play a considerable role in the phenotypic heterogeneity of CF, so we investigated the association of allelic variants in modifier genes that modulate the severity of lung function in a group of Mexican patients diagnosed with CF.

METHODS

We included 140 CF patients classified according to lung phenotype and analyzed 17 single nucleotide polymorphisms (SNPs) by TaqMan^® allelic discrimination.

RESULTS

We demonstrated that patients with GG or GC genotype of the allelic variant rs11003125 (MBL2-550) of the MBL2 gene exhibit most of the lung manifestations at an earlier age; and the rs1042713 allelic variant of ADRB2 gene, showed statistical difference only with the age of first spirometry. When we used the dominant model, the MBL2 allele rs11003125 (MBL2-550; p = 0.022, Odds Ratio (OR) 2.87, 95% CI 1.14-7.27) was significantly associated with CF patients as risk factor, and the ADRB2 allele rs1042713 (p.Arg16Gly; p = 0.005, Odds Ratio (OR) 0.37, 95% CI 0.19-0.75) was significantly associated with CF patients as protect factor.

CONCLUSIONS

Our findings suggest that the MBL2 and ADRB2 genes exerts an important genetic influence on the lung disease in our patients. Taking into account our results, we insist on not leaving aside this type of studies, since having techniques such as GWAS or WES will be able to advance in achieving a better quality of life for CF patients with severe lung disease.