Familial aggregation of SLE, RA, and other AI diseases in 1,177 lupus patients

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NinaFamilial aggregation of systemic lupus erythematosus, rheumatoid arthritis,and other autoimmune diseases in 1,177 lupus patients from the GLADELcohort.Alarcon-Segovia D, Alarcon-Riquelme ME, Cardiel MH, Caeiro F, Massardo L,Villa AR, Pons-Estel BA.University of Uppsala, Uppsala, Sweden.OBJECTIVE: To determine whether there is familial aggregation of systemiclupus erythematosus (SLE) and/or other autoimmune diseases in SLE patientsand to identify clinical differences between patients with and those withoutfamilial autoimmunity. METHODS: We interviewed members of the GrupoLatinoamericano de Estudio del Lupus Eritematoso (GLADEL) inception cohortof 1,214 SLE patients to ascertain whether they had relatives with SLEand/or other autoimmune diseases. Identified relatives were studied.Familial aggregation was tested using reported highest and intermediatepopulation prevalence data for SLE, rheumatoid arthritis (RA), or allautoimmune diseases, and studies were performed to identify the geneticmodel applicable for SLE. RESULTS: We identified 116 first-, second-, orthird-degree relatives with SLE, 79 with RA, 23 with autoimmune thyroiditis,3 with scleroderma, 1 with polymyositis, and 16 with other autoimmunediseases, related to 166 of the 1,177 SLE patients in the GLADEL cohort whoagreed to participate. Forty-two SLE patients had 2 or more relatives withan autoimmune disease. We found a lambda(sibling) of 5.8 and 29.0 for SLEand of 3.2-5.3 for RA, when comparing with their reported high orintermediate population prevalence, respectively. We also found familialaggregation for autoimmune disease in general (lambda(sibling) = 1.5) anddetermined that for SLE, a polygenic additive genetic model, rather than amultiplicative one, is applicable.CONCLUSION: In SLE there is familial aggregation of SLE, RA, and autoimmune disease in general. A polygenic additive model applies for SLE. American Indian-white Mestizo SLE patients and those with higher socioeconomic level were more likely to have familial autoimmunity.PMID: 15818688http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve & db=PubMed & list_uids=15818688 & dopt=Abstract