Lack of association between the genetic variations in the C-reactive protein gene and the risk of psoriasis among the Taiwanese

Association of C-Reactive Protein (rs1205) Gene Polymorphism with Susceptibility to Psoriasis in South Indian Tamils

INTRODUCTION

Psoriasis is a multi-factorial heritable T-helper Th-1/Th-17 mediated inflammatory disease, affecting the skin. It is associated with co-morbidities such as Cardiovascular Disease (CVD). C-Reactive Protein (CRP) is a good inflammatory marker. CRP rs1205 polymorphism is associated with circulating plasma CRP levels. Although there is association between the rs1205 Single Nucleotide Polymorphism (SNP) and CVD, there are no prior reports regarding the association of CRP rs1205 SNP with psoriasis susceptibility.

AIM

To study the association of the genetic variant rs1205 in the CRP gene with susceptibility to the disease and protein levels in South Indian Tamils with psoriasis.

MATERIALS AND METHODS

In this case-control genetic study, 300 cases of psoriasis and 300 age and gender matched controls were genotyped for CRP SNP rs1205 using Taq Man 5'allele discrimination assay at Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India from February 2014 to January 2016. Plasma high sensitivity (hs)-CRP levels were estimated by ELISA. Disease severity was assessed by Psoriasis Area Severity Index (PASI).

RESULTS

CRP genetic variation rs1205 was not associated with psoriasis risk in our South Indian Tamil population. However, the circulating levels of hs-CRP was significantly higher in patients with psoriasis, as compared with controls (p < 0.0001) and the protein levels were significantly associated with disease severity, as assessed by PASI scoring. No genotype was found significantly associated with PASI or CRP levels.

CONCLUSION

Our results suggest that plasma CRP levels are higher in patients with psoriasis and correlate with disease severity, whilst CRP rs1205 is not associated with susceptibility to psoriasis in South Indian Tamils.

The (CCTTT) n pentanucleotide repeat polymorphism in the inducible nitric oxide synthase gene promoter and the risk of psoriasis in Taiwanese

Recently, genome-wide association studies identified a novel psoriasis susceptibility locus tagged by two single-nucleotide polymorphisms (SNPs) rs4795067 and rs28998802, both of which are in the intronic region of inducible nitric oxide synthase (iNOS) gene. This study aimed to assess the role of (CCTTT) n pentanucleotide repeat polymorphisms in the promoter region of iNOS gene in Chinese-Taiwanese patients with psoriasis. In total, 280 patients with psoriasis and 512 control subjects were analyzed for the presence of the iNOS microsatellite polymorphism by polymerase chain reactions. The alleles were classified as S and L alleles according to the number of (CCTTT) n repeats, with the alleles with ≤13 repeats designated as S and alleles with ≥14 repeats designated as L alleles. The distribution of allele frequencies and genotypes was significantly different between the control and psoriasis groups (P = 0.040, and 0.014, respectively). After adjustment for age, sex, body mass index, smoking, diabetes, and hypertension, carriers of the LL genotype were 0.38 (95% confidence interval 0.16-0.95) times less likely than non-carriers to have psoriasis (P = 0.038). The promoter assays demonstrated that the iNOS promoter activity increases in parallel with the repeat number of (CCTTT) n in HaCaT cells. Approximately 70% of the study subjects were genotyped for rs4795067 and rs28998802. The rs4795067 is in linkage disequilibrium with the microsatellite L/S allelic classification. The association of iNOS microsatellite with psoriasis is independent of these known iNOS variants. Our results suggest that the iNOS microsatellite may contribute to the genetic background of psoriasis in Chinese-Taiwanese patients.

Microsatellite polymorphism in the heme oxygenase-1 gene promoter and the risk of psoriasis in Taiwanese

Psoriasis is a chronic disease characterized by inflammation of the skin. The expression of heme oxygenase-1 (HO-1), the rate-limiting enzyme involved in heme degradation, correlates well with the severity of psoriasis, and is a heritable trait. This study aimed to assess the role of (GT)(n) dinucleotide repeat polymorphisms in the promoter region of the HO-1 gene in Chinese-Taiwanese patients with psoriasis. In total, 288 patients with psoriasis and 542 control subjects were analyzed for the presence of the HO-1 microsatellite polymorphism by using polymerase chain reaction. The alleles were classified as the S and L alleles according to the number of (GT)(n) repeats, with the alleles with ≤26 repeats designated as S and alleles with ≥27 repeats designated as L alleles. The subjects were then classified as having S/S, S/L, or L/L genotypes according to each of their HO-1 alleles. No significant difference was observed in either the genotype or allele distribution between the patients and healthy controls. However, the average number of repeats of both alleles in psoriasis patients with late disease onset was lower than that of psoriasis patients with early disease onset (26.7 ± 3.2 vs. 27.5 ± 3.4; P = 0.043, adjusted for age and sex), but the difference was not significant after additional adjustment for body mass index, smoking, diabetes, and hypertension (P = 0.189). Our results suggest that the HO-1 microsatellite polymorphism may not contribute to the genetic background of psoriasis in Chinese-Taiwanese patients.