Ethnic differences for developing rheumatic fever in a low-income group living in Hawaii.

UNLABELLED: The risk factors responsible for acute rheumatic fever (ARF) are complex, in part, because group A streptococcus (GAS) infection is a prerequisite for this disease. We attempted to differentiate socioeconomic from genetic risk factors by studying subjects in a Hawaii pediatric cardiology clinic who qualified for Medicaid. This ethnically diverse group was unique because they maintained a low socioeconomic but generally healthy lifestyle with more limited risks than those living in extremely impoverished conditions. METHODS: Questionnaires were administered to consenting subjects in the clinic, who were divided into those diagnosed with ARF (n = 26) and those with other (primarily congenital) heart diseases (n = 41). RESULTS: The socioeconomic status of the ARF and non-ARF groups was lower than that of the Hawaii population in general, and little differences were noted between the groups. The ARF group, however, had slightly larger household sizes and more children than the non-ARF group. The greatest difference was in ethnicity. By the Fisher exact test, the number of Polynesians belonging to the ARF group was significantly greater than all other ethnicities (P = .005). Polynesians had an odds ratio > 4.80 of developing ARF, which increased to 6.33 when number of children per household was considered. CONCLUSION: The potential contribution of genetic predisposing factors for developing ARF was analyzed in subjects living in a homogeneously low socioeconomic level relative to the general Hawaii population. Polynesians were at highest risk when compared to other ethnicities living in similar socioeconomic conditions.

Cardiac Myosin Epitopes Recognized by Autoantibody in Acute and Convalescent Rheumatic Fever.

BACKGROUND: Acute rheumatic fever (ARF) is an autoimmune disorder associated with Streptococcus pyogenes infection. A prevailing hypothesis to account for this disease is that epitopes of self-antigens, such as cardiac myosin react to antibodies against S. pyogenes. The goal of our study was to confirm disease epitopes of cardiac myosin, identify immunodominant epitopes and to monitor the epitope response pattern in acute and convalescent rheumatic fever. METHODS: Enzyme-linked immunosorbant assays were used to determine epitopes immunodominant in acute disease and to track the immune response longitudinally to document any changes in the epitope pattern in convalescent sera. Multiplex fluorescence immunoassay was used to correlate anti-streptolysin O (ASO) and anti-human cardiac myosin antibodies. RESULTS: Disease-specific epitopes in rheumatic fever were identified as S2-1, 4 and 8. Epitopes S2-1, 4, 8 and 9 were found to be immunodominant in acute sera and S2-1, 8, 9, 29 and 30 in the convalescent sera. Frequency analysis showed that 50% of the ARF subjects responded to S2-8. S2-8 responders tended to maintain their epitope pattern throughout the convalescent period, whereas the S2-8 nonresponders tended to spread their responses to other epitopes later in the immune response. There was a significant correlation between anti-cardiac myosin and ASO titers. In addition, S2-8 responders showed elevated ASO titers compared with S2-8 non responders. CONCLUSION: Our studies confirm the existence of S2-1, 4 and 8 as disease-specific epitopes. We provide evidence that cardiac myosin S2-8 responders remain epitope stable in convalescence, whereas S2-8 nonresponders shift to neoepitopes. Multiplex data indicated a correlation between elevated ASO and anti-human cardiac myosin antibody titers. Mapping of cardiac myosin epitopes recognized in rheumatic fever sera may identify immunophenotypes of rheumatic fever.

Visiting consultant clinics to study prevalence rates of juvenile rheumatoid arthritis and childhood systemic lupus erythematosus across dispersed geographic areas.

OBJECTIVE: Visiting consultant clinics (VCC) may provide pediatric rheumatologic care to children in rural populations, but the clinical demands have not been studied. We studied whether these clinics could be effective in determining prevalence rates of rheumatic illness like juvenile rheumatoid arthritis (JRA) and childhood systemic lupus erythematosus (SLE) across large dispersed geographic areas. METHODS: The study population included children diagnosed with JRA or SLE at the only civilian pediatric rheumatology center in the State of Hawaii. Prevalence rates of these illnesses were then calculated for the urban and more rural neighbor island areas. VCC and prevalence data were calculated over a 10-year period. RESULTS: We found a lower prevalence of JRA in the urban area (38.3 per 100,000) when compared to the rural neighbor islands (63.2 per 100,000). However, an equivalent prevalence of SLE was found in the urban (24.0 per 100,000) and neighboring islands (21.8 per 100,000). Clinical demands increased significantly with the success of the VCC, and with an increase in pediatric rheumatologic staffing. CONCLUSION: We found an increased prevalence of JRA in rural areas when compared to urban areas. Similar prevalence rates of SLE suggested the finding was not due to referral bias alone. VCC are useful to estimate disease prevalence over large areas, and therefore make it possible to identify areas at greater risk. Further investigations are needed to elucidate the possible environmental and genetic factors that may explain the regional differences in JRA prevalence.

Precocious osteoarthritis in a family with recurrent COL2A1 mutation.

OBJECTIVE: To examine the genotypic and phenotypic characteristics of a Micronesian kindred with autosomal dominant precocious osteoarthritis (OA). METHODS: We reviewed records and radiographs of 3 index patients and their parents, administered questionnaires to 16 additional kindred members, performed whole-genome scans of 24 family members, and sequenced relevant genes from 16 family members. RESULTS: The kindred displayed early onset OA, enlarged epiphyses, platyspondyly, and brachydactyly with dysplastic findings consistent with mild spondyloepiphyseal dysplasia. Genetic analysis revealed an arginine to cysteine substitution at position 75 of the collagen 2A1 gene, a mutation that has been described in 4 other geographically distinct families. The major phenotypic differences among the families were in height (ranging from short to tall) and hearing loss noted in 3 of the 5 families. CONCLUSION: The presence of the COL2A1 Arg75Cys mutation in 5 geographically distinct areas helps to confirm a potential mutational hotspot. The diverse phenotypic spectrum suggests that modifier genes and environmental factors play a role in the expression of this mutation.