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Autoantibodies recognizing 3‐hydroxy‐3‐methylglutaryl‐coenzyme A reductase (HMGCR) are associated with statin exposure, the HLA allele DRB1*11:01, and necrotizing muscle biopsies in adult myositis patients. The aim of this study was to characterize the features of juvenile anti‐HMGCR‐positive myositis patients. The sera of 440 juvenile myositis patients were screened for anti‐HMGCR autoantibodies. Demographic and clinical features, responses to therapy, and HLA alleles were assessed. The features of anti‐HMGCR‐positive patients were compared to those of previously described adult patients with this autoantibody and to children with other myositis‐specific autoantibodies (MSAs). Five of 440 patients (1.1%) were anti‐HMGCR‐positive; none had taken statin medications. Three patients had rashes characteristic of juvenile dermatomyositis and 2 patients had immune‐mediated necrotizing myopathies. The median highest creatine kinase (CK) level of anti‐HMGCR‐positive subjects was 17,000 IU/liter. All patients had severe proximal muscle weakness, distal weakness, muscle atrophy, joint contractures, and arthralgias, which were all more prevalent in HMGCR‐positive subjects compared to MSA‐negative patients or those with other MSAs. Anti‐HMGCR‐positive patients had only partial responses to multiple immunosuppressive medications, and their disease often took a chronic course. The DRB1*07:01 allele was present in all 5 patients, compared to 26.25% of healthy controls (corrected P= 0.01); none of the 5 juvenile patients had DRB1*11:01. Compared to children with other MSAs, muscle disease appears to be more severe in those with anti‐HMGCR autoantibodies. Like adults, children with anti‐HMGCR autoantibodies have severe weakness and high CK levels. In contrast to adults, in anti‐HMGCR‐positive children, there is a strong association with HLA–DRB1*07:01.

To assess the extent of ethnic variation in the clinical expression of rheumatoid arthritis (RA) and the role of HLA–DRB1 alleles in this variation. We assessed consecutive RA patients for joint findings, subcutaneous nodules, laboratory and radiographic findings, and treatment. We typed HLA–DRB1 alleles to identify those that contain the shared epitope (SE). We adjusted ethnic comparisons for age and sex, and tested for ethnic heterogeneity in the effect of the SE. We studied 777 RA patients, 498 of whom were women (64%), 432 were Hispanic (56%), 272 were non-Hispanic white (NHW; 35%), 53 were African American (AA; 7%), and 20 were Asian (3%). Compared with NHW, Hispanics had significantly more tender joints (17 versus 11), more swollen joints (8 versus 7), more frequent rheumatoid factor (RF) positivity (93% versus 84%), higher erythrocyte sedimentation rate (ESR; 45 versus 36 mm/hr), and a lower number of lifetime disease-modifying antirheumatic drugs (1.9 versus 2.5). AA were older at onset (46 versus 44 years), had less frequent subcutaneous nodules (18% versus 28%), and higher ESR (42 versus 36 mm/hour) than did NHW. Hispanics and AA were more likely than NHW to be null for the SE (odds ratio [OR] = 4.59 for AA; and OR = 1.61 for Hispanics), and less likely to have 2 SE-carrying alleles (OR = 0.59 for Hispanics and OR = 0.25 for AA). The number of SE copies was associated with subcutaneous nodules, ESR, RF, and radiographic changes. Ethnic heterogeneity in the effect of the SE was modest. There is ethnic variation in the clinical expression of RA and in both the frequency and types of SE-carrying HLA–DRB1 alleles. Some ethnic variation in clinical findings is associated with differences in SE frequency. However, we found that the effect of the SE on the clinical features of RA varies little between ethnic groups.

To assess the extent of ethnic variation in the clinical expression of rheumatoid arthritis (RA) and the role of HLA–DRB1 alleles in this variation.We assessed consecutive RA patients for joint findings, subcutaneous nodules, laboratory and radiographic findings, and treatment. We typed HLA–DRB1 alleles to identify those that contain the shared epitope (SE). We adjusted ethnic comparisons for age and sex, and tested for ethnic heterogeneity in the effect of the SE.We studied 777 RA patients, 498 of whom were women (64%), 432 were Hispanic (56%), 272 were non‐Hispanic white (NHW; 35%), 53 were African American (AA; 7%), and 20 were Asian (3%). Compared with NHW, Hispanics had significantly more tender joints (17 versus 11), more swollen joints (8 versus 7), more frequent rheumatoid factor (RF) positivity (93% versus 84%), higher erythrocyte sedimentation rate (ESR; 45 versus 36 mm/hr), and a lower number of lifetime disease‐modifying antirheumatic drugs (1.9 versus 2.5). AA were older at onset (46 versus 44 years), had less frequent subcutaneous nodules (18% versus 28%), and higher ESR (42 versus 36 mm/hour) than did NHW. Hispanics and AA were more likely than NHW to be null for the SE (odds ratio [OR] = 4.59 for AA; and OR = 1.61 for Hispanics), and less likely to have 2 SE‐carrying alleles (OR = 0.59 for Hispanics and OR = 0.25 for AA). The number of SE copies was associated with subcutaneous nodules, ESR, RF, and radiographic changes. Ethnic heterogeneity in the effect of the SE was modest.There is ethnic variation in the clinical expression of RA and in both the frequency and types of SE‐carrying HLA–DRB1 alleles. Some ethnic variation in clinical findings is associated with differences in SE frequency. However, we found that the effect of the SE on the clinical features of RA varies little between ethnic groups.

To test the hypothesis that the influence of the HLA–DRB1 shared epitope (SE) on the clinical manifestations of rheumatoid arthritis (RA) differs between men and women. We assessed 777 consecutive RA patients for age at disease onset, articular manifestations, subcutaneous nodules, laboratory and radiographic findings, and treatment received. We typed HLA–DRB1 alleles by polymerase chain reaction–sequence-specific primer amplification and categorized the number of SE-containing alleles. We used regression models to adjust comparisons between the sexes for age and clustering by recruitment center, and included SE × sex interaction terms to look for heterogeneity between men and women in the effect of the SE. Among the 777 RA patients, 548 (71%) were women. Men and women differed significantly in the adjusted frequency of SE positivity (women 71.4% versus men 78.4%; P ≤ 0.001). The SE was associated with a younger age at symptom onset and RA diagnosis among men, but not among women. The SE likewise had a significant adverse effect on joint tenderness, swelling, and deformity among men only. The SE was associated with a higher erythrocyte sedimentation rate in women and more frequent positivity for rheumatoid factor among both men and women. There is heterogeneity between men and women in the effect of the SE on RA susceptibility and clinical expression. Further research is needed to understand the mechanism of this heterogeneity.