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%).

Autoantibodies to Mi-2 alpha and Mi-2 beta in patients with idiopathic inflammatory myopathy.

OBJECTIVES: The objective of this study was to compare the results obtained from different assays for the detection of anti-Mi-2 antibodies, which are important markers in the diagnosis of DM. METHODS: The study included 82 patients (68 females/14 males), most of whom had DM (n = 57), followed by PM (n = 16) and juvenile DM (n = 9). All samples were tested using a novel particle-based multi-analyte technology (PMAT) (Inova Diagnostics, research use only) in parallel with a line immunoassay (LIA: Euroimmun). To assess clinical specificity for the PMAT assay, a total of 775 disease and healthy controls were tested. RESULTS: 29 samples were positive by at least one test for anti-Mi-2 antibodies. Of those, 24 were Mi-2ß LIA+, five were Mi-2α LIA+ and 23 Mi-2 PMAT+. The comparison shows varying agreement between the different methods (kappa 0.27-0.77). When LIA results were used as reference for receiver operating characteristics analysis, high area under the curve values were found for both PMAT vs LIA Mi-2α and LIA Mi-2ß. When analysing the results in the context of the myositis phenotype, PMAT associated closest with the DM phenotype. In the control group, 3/775 controls (all low levels) were anti-Mi-2+ resulting in a sensitivity and specificity of 28.1% and 99.6%, respectively. CONCLUSION: Overall, good agreement was found between LIA and PMAT for anti-Mi-2 antibodies, which is important for the standardization of autoantibodies. Anti-Mi-2ß antibodies measured by PMAT tend be more highly associated with the clinical phenotype of DM.

Rheumatoid arthritis in Latin Americans enriched for Amerindian ancestry is associated with loci in chromosomes 1, 12, and 13, and the HLA class II region.

OBJECTIVE: To identify susceptibility loci for rheumatoid arthritis (RA) in Latin American individuals with admixed European and Amerindian genetic ancestry. METHODS: Genotyping was performed in 1,475 patients with RA and 1,213 control subjects, using a customized BeadArray containing 196,524 markers covering loci previously associated with various autoimmune diseases. Principal components analysis (EigenSoft package) and Structure software were used to identify outliers and define the population substructure. REAP software was used to define cryptic relatedness and duplicates, and genetic association analyses were conducted using Plink statistical software. RESULTS: A strong genetic association between RA and the major histocompatibility complex region was observed, localized within BTNL2/DRA-DQB1- DQA2 (P = 7.6 × 10(-10) ), with 3 independent effects. We identified an association in the PLCH2-HES5-TNFRSF14-MMEL1 region of chromosome 1 (P = 9.77 × 10(-6) ), which was previously reported in Europeans, Asians, and Native Canadians. We identified one novel putative association in ENOX1 on chromosome 13 (P = 3.24 × 10(-7) ). Previously reported associations were observed in the current study, including PTPN22, SPRED2, STAT4, IRF5, CCL21, and IL2RA, although the significance was relatively moderate. Adjustment for Amerindian ancestry improved the association of a novel locus in chromosome 12 at C12orf30 (NAA25) (P = 3.9 × 10(-6) ). Associations with the HLA region, SPRED2, and PTPN22 improved in individuals positive for anti-cyclic citrullinated peptide antibodies. CONCLUSION: Our data define, for the first time, the contribution of Amerindian ancestry to the genetic architecture of RA in an admixed Latin American population by confirming the role of the HLA region and supporting the association with a locus in chromosome 1. In addition, we provide data for novel putative loci in chromosomes 12 and 13.

Impact of genetic ancestry and sociodemographic status on the clinical expression of systemic lupus erythematosus in American Indian-European populations.

OBJECTIVE: American Indian-Europeans, Asians, and African Americans have an excess morbidity from systemic lupus erythematosus (SLE) and a higher prevalence of lupus nephritis than do Caucasians. The aim of this study was to analyze the relationship between genetic ancestry and sociodemographic characteristics and clinical features in a large cohort of American Indian-European SLE patients. METHODS: A total of 2,116 SLE patients of American Indian-European origin and 4,001 SLE patients of European descent for whom we had clinical data were included in the study. Genotyping of 253 continental ancestry-informative markers was performed on the Illumina platform. Structure and Admixture software were used to determine genetic ancestry proportions of each individual. Logistic regression was used to test the association between genetic ancestry and sociodemographic and clinical characteristics. Odds ratios (ORs) were calculated with 95% confidence intervals (95% CIs). RESULTS: The average American Indian genetic ancestry of 2,116 SLE patients was 40.7%. American Indian genetic ancestry conferred increased risks of renal involvement (P < 0.0001, OR 3.50 [95% CI 2.63- 4.63]) and early age at onset (P < 0.0001). American Indian ancestry protected against photosensitivity (P < 0.0001, OR 0.58 [95% CI 0.44-0.76]), oral ulcers (P < 0.0001, OR 0.55 [95% CI 0.42-0.72]), and serositis (P < 0.0001, OR 0.56 [95% CI 0.41-0.75]) after adjustment for age, sex, and age at onset. However, age and sex had stronger effects than genetic ancestry on malar rash, discoid rash, arthritis, and neurologic involvement. CONCLUSION: In general, American Indian genetic ancestry correlates with lower sociodemographic status and increases the risk of developing renal involvement and SLE at an earlier age.

Genetically determined Amerindian ancestry correlates with increased frequency of risk alleles for systemic lupus erythematosus.

OBJECTIVE: To assess whether genetically determined Amerindian ancestry predicts increased presence of risk alleles of known susceptibility genes for systemic lupus erythematosus (SLE). METHODS: Single-nucleotide polymorphisms (SNPs) within 16 confirmed genetic susceptibility loci for SLE were genotyped in a set of 804 Mestizo lupus patients and 667 Mestizo healthy controls. In addition, 347 admixture informative markers were genotyped. Individual ancestry proportions were determined using STRUCTURE. Association analysis was performed using PLINK, and correlation between ancestry and the presence of risk alleles was analyzed using linear regression. RESULTS: A meta-analysis of the genetic association of the 16 SNPs across populations showed that TNFSF4, STAT4, ITGAM, and IRF5 were associated with lupus in a Hispanic Mestizo cohort enriched for European and Amerindian ancestry. In addition, 2 SNPs within the major histocompatibility complex region, previously shown to be associated in a genome-wide association study in Europeans, were also associated in Mestizos. Using linear regression, we predicted an average increase of 2.34 risk alleles when comparing an SLE patient with 100% Amerindian ancestry versus an SLE patient with 0% Amerindian ancestry (P < 0.0001). SLE patients with 43% more Amerindian ancestry were predicted to carry 1 additional risk allele. CONCLUSION: Our results demonstrate that Amerindian ancestry is associated with an increased number of risk alleles for SLE.

Effects of Amerindian Genetic Ancestry on Clinical Variables and Therapy in Patients with Rheumatoid Arthritis.

OBJECTIVE: To define whether Amerindian genetic ancestry correlates with clinical and therapeutic variables in admixed individuals with rheumatoid arthritis (RA) from Latin America. METHODS: Patients with RA (n = 1347) and healthy controls (n = 1012) from Argentina, Mexico, Chile, and Peru were included. Samples were genotyped for the Immunochip v1 using the Illumina platform. Clinical data were obtained through interviews or the clinical history. RESULTS: Percentage of Amerindian ancestry was comparable between cases and controls. Morning stiffness (p < 0.0001, OR 0.05), rheumatoid factor (RF; p < 0.0001, OR 0.22), radiographic changes (p < 0.0001, OR 0.05), and higher number of criteria were associated with lower Amerindian ancestry after Bonferroni correction. Higher Amerindian ancestry correlated only with weight loss (pBonferroni < 0.0001, OR 2.85). Increased Amerindian ancestry correlated with higher doses of azathioprine (p < 0.0001, OR 163.6) and sulfasalazine (p < 0.0001, OR 48.6), and inversely with methotrexate (p = 0.001, OR 0.35), leflunomide (p = 0.001, OR 0.16), and nonsteroidal antiinflammatory drugs (pBonferroni = 0.001, OR 0.37). Only the presence of RF and weight loss were modified after confounders adjustment. CONCLUSION: Amerindian ancestry protects against most major clinical criteria of RA, but regarding the association of RF with increased European ancestry, age, sex, and smoking are modifiers. Ancestry also correlates with the therapeutic profiles.

Genome-Wide Association Study in an Amerindian Ancestry Population Reveals Novel Systemic Lupus Erythematosus Risk Loci and the Role of European Admixture.

OBJECTIVE: Systemic lupus erythematosus (SLE) is a chronic autoimmune disease with a strong genetic component. We undertook the present work to perform the first genome-wide association study on individuals from the Americas who are enriched for Native American heritage. METHODS: We analyzed 3,710 individuals from the US and 4 countries of Latin America who were diagnosed as having SLE, and healthy controls. Samples were genotyped with HumanOmni1 BeadChip. Data on out-of-study controls genotyped with HumanOmni2.5 were also included. Statistical analyses were performed using SNPtest and SNPGWA. Data were adjusted for genomic control and false discovery rate. Imputation was performed using Impute2 and, for classic HLA alleles, HiBag. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated. RESULTS: The IRF5-TNPO3 region showed the strongest association and largest OR for SLE (rs10488631: genomic control-adjusted P [Pgcadj ] = 2.61 × 10(-29), OR 2.12 [95% CI 1.88-2.39]), followed by HLA class II on the DQA2-DQB1 loci (rs9275572: Pgcadj = 1.11 × 10(-16), OR 1.62 [95% CI 1.46-1.80] and rs9271366: Pgcadj = 6.46 × 10(-12), OR 2.06 [95% CI 1.71-2.50]). Other known SLE loci found to be associated in this population were ITGAM, STAT4, TNIP1, NCF2, and IRAK1. We identified a novel locus on 10q24.33 (rs4917385: Pgcadj = 1.39 × 10(-8)) with an expression quantitative trait locus (eQTL) effect (Peqtl = 8.0 × 10(-37) at USMG5/miR1307), and several new suggestive loci. SLE risk loci previously identified in Europeans and Asians were corroborated. Local ancestry estimation showed that the HLA allele risk contribution is of European ancestral origin. Imputation of HLA alleles suggested that autochthonous Native American haplotypes provide protection against development of SLE. CONCLUSION: Our results demonstrate that studying admixed populations provides new insights in the delineation of the genetic architecture that underlies autoimmune and complex diseases.

[Clinical and epidemiologic characteristics of dengue cases: the experience of a general hospital in Culiacan, Sinaloa, Mexico]. / Caracterización clínica y epidemiológica de los casos de dengue: experiencia del Hospital General de Culiacán, Sinaloa, México.

OBJECTIVES: To document the clinical and epidemiological characteristics present in dengue patients served by a hospital in Culiacan, Sinaloa, Mexico. METHODS: A cross-sectional, observational, and analytical study was carried out at the Hospital General Dr. Bernardo J. Gastélum de Culiacan from 1 October to 2 December 2003. Associations between the independent variables (the patients' clinical and epidemiological characteristics) and the dependent variable (confirmed hemorrhagic dengue) were determined through simple regression analysis. The variables that were significantly associated (P < 0.05) were submitted to multifactorial logistic regression analysis. RESULTS: Of the only 241 cases that met the study's inclusion criteria (207 dengue and 34 hemorrhagic dengue), the mean age was 34.7 +/- 15.1 years. According to the results of the multifactorial analysis (adjusted by age, sex, and the presence of dengue cases at the geographic location), the variables predictive of major complications of the disease were: the presence of ascites (odds ration [OR] = 22.12; 95% confidence interval [95%CI]: 5.00-97.87), gingivorrhagia (OR = 7.35; 95%CI: 2.11-25.61), hematemesis (OR = 7.40; 95%CI: 1.04-52.42), thrombocytopenia (platelets from 40,001/mm(3)-60,000/mm(3)) (OR = 5.43; 95%CI: 1.58-18.72), conjunctival hyperemia (OR = 4.27; 95%CI: 1.37-13.28), persistent vomiting (OR = 3.04; 95%CI: 1.05-8.80), and the absence of nasal congestion (OR = 0.015; 95%CI: 0.0004-0.473). CONCLUSIONS: The presence of ascites, gingivorrhagia, hematemesis, thrombocytopenia (with platelet values from 40,001/mm(3)-60,000/mm(3)), and persistent vomiting were confirmed as warning signs of an imminent dengue attack. Platelet counts of > 100,000/mm(3) were confirmed in cases with acute clinical symptoms (capillary leak) that were not classified as hemorrhagic dengue due to falling short of the criteria established by WHO.

Caracterización clínica y epidemiológica de los casos de dengue: experiencia del Hospital General de Culiacán, Sinaloa, México / Clinical and epidemiologic characteristics of dengue cases: the experience of a general hospital in Culiacan, Sinaloa, Mexico

OBJETIVO: Documentar las características clínicas y epidemiológicas de los pacientes con dengue atendidos en un hospital de Culiacán, Sinaloa, México. MÉTODOS: Estudio transversal, observacional y analítico realizado en el Hospital General Dr. Bernardo J. Gastélum de Culiacán entre el 1 de octubre y el 2 de diciembre de 2003. Se evaluó la asociación entre las variables independientes (las características clínicas y epidemiológicas de los pacientes) y la variable dependiente (diagnóstico confirmado de dengue hemorrágico) mediante el análisis de regresión simple. Las variables que mostraron una relación significativa (P < 0,05) se incluyeron en el análisis de regresión logística multifactorial. RESULTADOS: En los 241 casos que cumplieron los criterios de inclusión para este estudio (207 de dengue y 34 de dengue hemorrágico), la edad promedio fue de 34,7 ± 15,1 años. Según los resultados del análisis multifactorial ajustado por la edad, el sexo y la presencia de casos de dengue en la localidad, las variables con valor predictivo de una mayor gravedad de la enfermedad fueron: la presencia de ascitis (OR = 22,12; IC95 por ciento: 5,00 a 97,87), la gingivorragia (OR = 7,35; IC95 por ciento: 2,11 a 25,61), la hematemesis (OR = 7,40; IC95 por ciento: 1,04 a 52,42), la trombocitopenia (plaquetas entre 40 001/mm³ y 60 000/mm³) (OR = 5,43; IC95 por ciento: 1,58 a 18,72), la hiperemia conjuntival (OR = 4,27; IC95 por ciento: 1,37 a 13,28), los vómitos persistentes (OR = 3,04; IC95 por ciento: 1,05 a 8,80) y la ausencia de congestión nasal (OR = 0,015; IC95 por ciento: 0,0004 a 0,473). CONCLUSIONES: Se confirmó el valor de la presencia de ascitis, gingivorragia, hematemesis, trombocitopenia (con valores de plaquetas entre 40 001/mm³ y 60 000/mm³) y vómitos persistentes como signos de alarma que anuncian la inminencia del choque por dengue. Se observaron conteos plaquetarios > 100 000/mm3 en casos con cuadros clínicos graves (fuga capilar) que no se...

OBJECTIVES: To document the clinical and epidemiological characteristics present in dengue patients served by a hospital in Culiacan, Sinaloa, Mexico. METHODS: A cross-sectional, observational, and analytical study was carried out at the Hospital General Dr. Bernardo J. Gastélum de Culiacan from 1 October to 2 December 2003. Associations between the independent variables (the patients' clinical and epidemiological characteristics) and the dependent variable (confirmed hemorrhagic dengue) were determined through simple regression analysis. The variables that were significantly associated (P < 0.05) were submitted to multifactorial logistic regression analysis. RESULTS: Of the only 241 cases that met the study's inclusion criteria (207 dengue and 34 hemorrhagic dengue), the mean age was 34.7 ± 15.1 years. According to the results of the multifactorial analysis (adjusted by age, sex, and the presence of dengue cases at the geographic location), the variables predictive of major complications of the disease were: the presence of ascites (odds ration [OR] = 22.12; 95 percent confidence interval [95 percentCI]: 5.00-97.87), gingivorrhagia (OR = 7.35; 95 percentCI: 2.11-25.61), hematemesis (OR = 7.40; 95 percentCI: 1.04-52.42), thrombocytopenia (platelets from 40001/mm³- 60000/mm³) (OR = 5.43; 95 percentCI: 1.58-18.72), conjunctival hyperemia (OR = 4.27; 95 percentCI: 1.37-13.28), persistent vomiting (OR = 3.04; 95 percentCI: 1.05-8.80), and the absence of nasal congestion (OR = 0.015; 95 percentCI: 0.0004-0.473). CONCLUSIONS: The presence of ascites, gingivorrhagia, hematemesis, thrombocytopenia (with platelet values from 40001/mm³-60000/mm³), and persistent vomiting were confirmed as warning signs of an imminent dengue attack. Platelet counts of > 100000/mm3 were confirmed in cases with acute clinical symptoms (capillary leak) that were not classified as hemorrhagic dengue due to falling short of the criteria established by WHO.