Myositis-Specific Antibodies and Myositis-Associated Antibodies in Patients With Idiopathic Inflammatory Myopathies From the PANLAR Myositis Study Group.

BACKGROUND: Dermatomyositis (DM) and polymyositis (PM) are forms of idiopathic inflammatory myopathies (IIMs), which are associated with the production of autoantibodies that are useful in the diagnosis and prognosis of the disease. OBJECTIVE: The aim of this study was to determine the frequency of antinuclear autoantibodies (ANAs), myositis-specific autoantibodies (MSAs), and myositis-associated autoantibodies (MAAs) in 6 Latin American countries. METHODS: Two hundred ten patients with IIM were included in this cross-sectional study from 2014 to 2017: 112 from Mexico, 46 from Colombia, 20 from Peru, 16 from the Dominican Republic, 10 from Argentina, and 6 from Guatemala. Antinuclear autoantibodies were detected by indirect immunofluorescence on HEp-2 cells. MSAs and MAAs were tested by a line immunoassay method. Mann-Whitney U and χ2 tests were used for statistical analysis. RESULTS: Of the 210 IIM patients, 139 (66.2%) had DM, 59 (28%) PM, and 12 (5.7%) juvenile DM. The mean age was 43.5 (6-79 years); 158 (75.2%) were female, and 52 (24.8%) were male. The overall frequency of ANA was 60%. The most frequent patterns were fine speckled (AC-4) (78.3%) and cytoplasmic (AC-19) (6.45%). The most frequent MSA were anti-Mi-2 (38.5%) and anti-Jo-1 (11.9%). Anti-Mi-2 was more frequent in patients from Colombia (40.1%). The MAA more frequent were anti-Ro-52/TRIM21 (17.6%) and anti-PM-Scl75 (7.5%). CONCLUSIONS: This is the first study of ANA, MSA, and MAA in patients from 6 countries from the Panamerican League against Rheumatism myositis study group. We observed a general prevalence of 60% of ANA. In relation to MSA and MAA, anti-Mi-2 was the more frequent (38.5%).

Scleroderma in the Caribbean: characteristics in a Dominican case series.

INTRODUCTION: Scleroderma is a rare disease with limited data in Latin America. Preliminary genetic studies suggest a strong African ascendance in the Dominican Republic, which could modulate the expression of the disease. The objective of this study is to describe the clinical and demographic characteristics of scleroderma in a series of 26 Dominican patients. MATERIALS AND METHODS: Patients who fulfilled the EULAR/ACR criteria for scleroderma were selected from the Rheumatology Department of a tertiary health center; systemic sclerosis subtypes were defined according to the EULAR classification. Clinical and demographic information was obtained retrospectively from clinical records. RESULTS: Mean age at time of onset was 32.6±15 years; 68% of patients had 40 years of age or less. 73% of patients was feminine, with a female:male ratio of 2.7:1. The most affected systems were pulmonary and gastrointestinal; renal affection was scarce. Anti-Scl-70 antibodies were positive in 64% of patients, sometimes in coexistence with anti-centromere antibodies. CONCLUSIONS: The prevalence of systemic sclerosis is lower in the Dominican population than the reported elsewhere. The age of onset of the disease seems to be lower in the Dominican population than that reported in literature. A different pattern of autoantibodies is observed in this population.