Background: Psoriasis is a multifactorial disease with wide range of clinical manifestations. Musculoskeletal manifestations of psoriasis include a combination of axial disease, peripheral arthritis, enthesitis and dactylitis. The tumor necrosis factor α (TNFα) gene is proposed as a fundamental gene in psoriatic arthritis (PsA). Aim of the work is to detect frequency of TNF α gene -308 and +489 polymorphisms genotypes among psoriatic and PsA patients and assess risk for psoriasis and PsA.
Subjects and methods: A case control study was conducted in Rheumatology and Rehabilitation Department, Zagazig University Hospitals on 96 subjects. They were divided into three equal groups (PsA, cutaneous only psoriasis (PsC) and control). Full history taking, clinical examination and assessment of PsA activity by composite psoriatic disease activity index (CPDAI) were done. Laboratory investigations included CBC, ESR, CRP, RF, kidney and liver function tests. Detection of TNFα gene -308 and +489 polymorphisms was performed using PCR RFLP (restriction fragment length polymorphism) technique.
Results: Regarding TNF (+489) genotyping, AA and GA genotypes and A allele were more frequent in PsA and PsC patients than in controls. The A allele increased the risk for PsA and psoriasis by 8.4 and 5.9 folds respectively. TNF (+489) GA genotype was associated with higher activity of PsA. Regarding TNF (-308), there was no significant difference in genotypes frequency among three groups and no relation with PsA disease activity.
Conclusions: TNF (+489) A allele carried risk for PsA and psoriasis and TNF (+489) GA genotype was associated with higher activity of PsA.