| IntroductionIdiopathic inflammatory myopathies ( IIM) , including polymyositis ( PM) and dermatomyositis ( DM) , are regarded as systemic autoimmune disorders primarily affecting the locomotor system, and with dermal as well as internal organ involvement that can vary considerably. The classical form of the disease presents with a characteristic rash over the face, truck, and extensor surface, along with muscle weakness. While the skin and muscle manifestations usually occur i within a few months of one another, rarely, the classical skin findings may occur without the development of overt muscle disease. Moreover, in these serological-ly defined patient groups, a distinct immunogenetic background often seems to influence susceptibility to the production of a specific autoantibody. Investigations of multiethnic patients with myositis had suggested that the HLA - B8, DR3 and DQA1 * 0501 alleles occurring in linkage disequilibrium in certain ethnic population, especially white population. A similar approach with adult myositis patients in Chinese has not yet been fully described. Thus, in the present study, we further investigated the correlation of HLA - A, B, DRB1 and DQB1 alleles with various forms of myositis in Chinese patients.Materials and methods1. Sample composition: Fifty - two adults northern Chinese patients with polymyositis / dermatomyositis (PM/DM) were studied (11 were male, and 41 were female). Among these patients, 14 and 38 were classified as having PM and DM, respectively, using the criteria proposed by Bohan and Peter. Ten of these had myositis overlaping interstitial lung disease concomitantly. Controls ( n = 90 for HLA - A, B typing, n = 168 for HLA - DRB1 and n = 160 for HLA -DQB1 alleles typing) were volunteers without such disease or family history.2. HLA typing; HLA - A, B, DRB1 alleles were determined using poly-merase chain reaction -sequence specific primers (PCR -SSP) methods.3. Statistical Analysis; HLA-A, B, DRB1 and DQB1 alleles were compared between patients and controls using Fishers exact test. All P values and relative risk ( RR) were calculated from the same 2 2 contingency tables. To calculate a RR when a cell contained a 0, the formula of RR = (2a + l) (2d + l)/(2b + l) (2c + l) was used.Results1. HLA - A, B antigens in patients with PM/DM:Among 52 patients with PM/DM, HLA - A32 and B52 (5) were significandy higher compared with controls (n=90) (P=0.017, RR = 9.28; P=0. 025, RR =9.47, respectively). And HLA - A32 was not detected among controls.In 38 patients with DM, there were significandy increased frequencies of theHLA-A32, B13, B52 and B56 (P=0.007, RR=3.77; P=0.048, RR = 2.44; P=0.027, RR = 10.5; P=0.027, RR = 10.5). The two groups did not differ significandy in PM of patients and controls. HLA - A3 and B18 alleles were significandy increased in myositis patients with overlaping interstitial lung disease compared controls (P =0. 007, RR = 18. 9; P =0.009, RR =53.2).2. HLA - DRB1 alleles in patients with PM/DM:In all patients (n =52) with PM/DM, the frequencies of HLA - DRB1 * 040Ix and DRB1 * 120x alleles were significandy higher than controls (n = 168) (P=0.004, RR=3.06; P=0.012, RR=3.01, respectively). In patients with PM (n = 14) and myosids with overlaping interstitial lung disease (n = 10) , the difference were no statistically significant.3. HLA - DQB1 alleles in patients widi PM/DM:HLA - DQB1 * 0401 allele was significandy increased in PM/DM compared the controls ( n = 160) ( P = 0. 004, RR = 3. 56 ). Among 38 patients with DM, DQB1 * 0401 allele was significandy increased in patients (P =0.Oil, RR =3.45). In PM and myositis with overlaping interstitial lung disease, the difference were no statistically significant.DiscussionThe genes most commonly considered when investigating immunogenetic associations with autoimmune dieases, including inflammatory muscle diseases (IMD) , are those encoded in the major histocompatibility complex ( MHC ) , the T - cell receptor (TCR) genes and th... |
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