HLA class I and II and TNF-α gene polymorphisms in sarcoidosis patients

Introduction: Several factors suggest a genetic predisposition to sarcoidosis, namely the recognition of race as a risk factor and the occurrence of familial clustering of cases. Several studies have reported an association of sarcoidosis and HLA class I and especially class II alleles in different populations. Aim: HLA class I, class II and TNF-α genotyping in a group of sarcoidosis patients and its relation with clinical presentation and outcome. Material and methods: A total of 104 sarcoidosis patients were included. Clinical presentation, functional, radiology, BAL findings and organ involvement were studied. HLA - A*, -B*, -C*, DRB1*, DQB1* and TNF-α were genotyped by molecular biology methods. DNA was extracted from peripheral blood and PCR-SSP and PCR-reverse hybridisation methods were used. Allele frequencies were compared with controls from the same region. The X² test was used for discrete values and the Kruskal-Wallis test for continuous values. Results: When patients were compared with controls we noticed increased frequencies of B*08 (10.6% vs. 6.1%), O.R.=1.8, C.I.=[1.1;3.1], p=0.02; DRB1*12 (4.3% vs. 1.7%), O.R.=2.63, C.I.=[1.1;6.1], p=0.03. Patients with erythema nodosum have increased frequencies of the alleles DRB1*03 (28% vs. 9.3%), R.R.=2.39, C.I.=[1.5;3.8], p_c=0.01 and DQB1*02 (38% vs. 18%), R.R.=2.1, C.I.=[1.3;3.3], p_c=0.02. Allele DQB1*03 is decreased in patients with obstructive pattern R.R.=0.53, C.I.=[0.3;0.9], p_c=0.05. Allele DRB1*15 is related to restrictive pattern and reduced diffusion capacity (21.1% vs. 6.6%), R.R.=2.46, C.I.=[1.35;4.48], p=0.01 and (18.1% vs. 3.8%), R.R.=1.87, p_c=0.05 respectively. The TNF-α A/A (high) genotype is significantly associated with erythema nodosum (p=0.04). Conclusions: These data add support to the genetic association of HLA class I and II with sarcoidosis in terms of susceptibility, type of presentation, severity and outcome. Moreover as previously described in other populations,the TNF-α A/A (high) genotype has a significant association with erythema nodosum.