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ESSENTIALS OF DIAGNOSIS
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ESSENTIALS OF DIAGNOSIS
Occurs mainly in young women.
Rash over areas exposed to sunlight.
Joint symptoms in 90% of patients.
Anemia, leukopenia, thrombocytopenia.
Glomerulonephritis, CNS disease, and complications of antiphospholipid antibodies are major sources of disease morbidity.
Serologic findings: antinuclear antibodies (100%), anti–double-stranded DNA antibodies (approximately two-thirds), and low serum complement levels (particularly during disease flares).
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GENERAL CONSIDERATIONS
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SLE is an inflammatory autoimmune disorder of autoantibodies to nuclear antigens. It can affect multiple organ systems. Many of its clinical manifestations are secondary to the trapping of antigen-antibody complexes in capillaries of visceral structures or to autoantibody-mediated destruction of host cells (eg, thrombocytopenia). The clinical course is marked by spontaneous remission and relapses. The severity may vary from mild and episodic to a rapidly fulminant, life-threatening illness.
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The incidence of SLE is influenced by many factors, including sex, environmental exposures, and genetic inheritance. About 85% of patients are women and most cases develop after menarche and before menopause. Among older individuals, the sex distribution is more equal. Race is also a factor, as SLE occurs in 1:250 Black women but in 1:1000 White women. There are familial occurrence of SLE, and the disorder is concordant in 25–70% of identical twins. If a mother has SLE, her daughters’ risks of developing the disease are 1:40 and her sons’ risks are 1:250. Serologic abnormalities (positive antinuclear antibody) are seen in asymptomatic family members, and the prevalence of other rheumatic diseases is increased among close relatives of patients. The importance of specific genes in SLE is emphasized by the high frequency of certain HLA haplotypes, especially DR2 and DR3, and null complement alleles (see eTable 22–1).
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