Clinical, serological and HLA profiles in non-Caucasian UK idiopathic inflammatory myopathy.

Clinical, serological and HLA profiles in non-Caucasian UK idiopathic inflammatory myopathy SIR, Since 2000, the UK Adult Onset Myositis Immunogenetic Collaboration (AOMIC) has recruited idiopathic inflammatory myopathy (IIM) cases across the UK. In this brief report, we summarize the clinical, serological and HLA Class II status of non-Caucasian IIM cases, to ascertain whether differences are observed among UK IIM ethnic populations. DNA was available from 28 UK non-Caucasian IIM cases. Adult IIM patients, aged 518 years of age at disease onset, with probable or definite myositis [1] were recruited through AOMIC [2]. Data were also available from 303 UK Caucasian IIM cases previously described [2, 3]. The collaborating AOMIC physicians confirmed interstitial lung disease (ILD) and cancer-associated myositis (CAM) [4] by relevant investigations. Radio-immunoprecipitation was used for determination of myositis-specific antibodies (anti-previously described [2, 4]. This study was approved by the local research ethics committee and informed consent was obtained according to the Declaration of Helsinki. A Wilcoxon–Mann– Whitney test was used to compare the age of onset between Caucasians and non-Caucasians. Associations were calculated from 2 Â 2 contingency tables using the chi-squared test. Of the 28 non-Caucasian IIM cases, 14 were Asian, 12 African/ Afro-Caribbean and 2 of mixed-race origin (Table 1). Sixty-four percent of the non-Caucasian IIM cases were females, compared with 71% female Caucasian cases (P ¼ 0.46). The median age of onset of the non-Caucasian cohort was significantly lower than that of the Caucasian cohort [non-Caucasians, 37 years (inter-After stratification by gender, this observation was only significantly lower in non-Caucasian females [non-Caucasians females, 33 years (27, 41) vs Caucasian females, 49 years (38, 60), P ¼ 0.0001]. No significant difference for age of onset was noted between African/Afro-Caribbean or Asian cases. CAM was not detected in the non-Caucasian cohort, but was present in 6% of the Caucasian IIM cohort, and in 15% of the DM cases [4]. With respect to ILD, there were eight (29%) non-Caucasian IIM cases and six of seven (86%) anti-synthetase antibody-positive cases. Although a higher frequency of ILD was observed in African/Afro-Caribbean (35%) compared with Asian (18%) cases, due to the small sample size this was not statistically significant (P ¼ 0.24). This difference was not attributable to differences in anti-synthetase antibody frequency. In comparison, the overall frequency of ILD in the Caucasian cohort was 20%, and 44% in anti-synthetase positive cases. Within the non-Caucasian cohort, only PM cases possessed anti-Jo-1 …