ORIGINAL ARTICLE C-reactive protein gene and Toll-like receptor 4 gene polymorphisms can relate to the development of psoriatic arthritis Ayla Akbal & Sevilay Oğuz & Ferhat Gökmen & Serhat Bilim & Hatice Reşorlu & Fatma Sılan & Ahmet Uludağ Received: 27 February 2014 /Revised: 5 March 2014 /Accepted: 11 March 2014 # Clinical Rheumatology 2014 Abstract We aimed to determine in psoriatic arthritis (PsA) patients the Toll-like receptor (TLR) 4 and C- reactive gene (CRP) polymorphisms and allele frequency and to investigate the relationship between clinical param- eters and gene polymorphisms. We enrolled in this study 31 PsA and 41 healthy control subjects. PsA diagnosis was according to CASPAR criteria. Bath ankylosing spon- dylitis diseases activity index, Maastricht ankylosing spon- dylitis enthesitis score, and Bath ankylosing spondylitis functional index were measured. C, A, and T alleles of CRP and A and G alleles of TLR 4 were determined using the analysis of melting curves after real-time PCR. CRP A, C, and T allele frequency in controls was 26.8, 73.2, and 36.6 %, respectively. In the PsA patient group, A, C, and T allele frequency was 9.7, 87.1, and 12.9 %, respectively. Between control and PsA groups, there was a significant difference in A, C, and T allele frequency (P =0.008, 0.038, and 0.001, respectively). The frequency of CRP gene polymorphisms (CA, AA, CT, TA, and TT alleles) in the control group was 56.1 % and in the PsA group was 22.6 %. There was a significant difference between the two groups (P =0.004). The absence of a CRP gene polymorphism was a risk factor for PsA (odds ratio 4.3, 95 % CI; 1.5–12.4, P =0.005). TLR gene hap- loid frequency was investigated, and all control subjects had the wild-type AA allele. PsA patient GA allele fre- quency was 6.5 %. There was no significant difference between the two groups (P =0.182). GA mutant allele frequency was related to PsA (odds ratio 7.03, 95 % CI; 0.32–151.9, P =0.214). We have shown that CRP gene polymorphisms are higher in control subjects than PsA patients, and TLR 4 gene polymorphisms were found to be related to PsA. Keywords C-reactive gene . Polymorphisms . Psoriatic arthritis . Toll-like receptor 4 Introduction Psoriasis (Ps) is defined as a chronic and inflammatory skin disease affecting multiple systems. Psoriatic arthritis (PsA) is a common manifestation of Ps. PsA has been identified among spondyloarthropathic diseases, and the usual charac- teristic finding includes axial and peripheral joint involvement [1]. Several factors play a role in the pathogenesis of PsA. However, there is no clear definition of its pathogenesis. Previous studies have revealed several genetic factors related to the pathogenesis of PsA. Many authors have claimed that there is an immunological mechanism underlying the patho- genesis of PsA [2–5]. Recent studies have demonstrated that Toll-like receptors (TLR) have a major role in immunological mechanisms. Toll-like receptors in the immune system have a significant role in antigen recognition and initiation of an No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated. A. Akbal (*) : F. Gökmen : S. Bilim : H. Reşorlu Department of Physical Medicine and Rehabilitation, Çanakkale Onsekiz Mart University, Çanakkale, Turkey e-mail: draylayavuz@gmail.com S. Oğuz Department of Dermatology, Çanakkale Onsekiz Mart University, Çanakkale, Turkey F. Sılan : A. Uludağ Department of Medical Genetic, Çanakkale Onsekiz Mart University, Çanakkale, Turkey A. Akbal : S. Oğuz : F. Gökmen : S. Bilim : H. Reşorlu : F. Sılan : A. Uludağ Faculty of Medicibe, Çanakkale Onsekiz Mart University, Kepez, 17100 Çanakkale, Turkey Clin Rheumatol DOI 10.1007/s10067-014-2581-7