<prompt> Antibodies against double stranded DNA and smooth muscle antigens are virtually diagnostic of:Systemic sclerosisSystemic Lupus ErythematosusSjogrens diseaseWegeners granulomatosis  <response>: Ans. b Systemic Lupus Erythematosus. Ref. Robbins Pathologic Basis of Disease 7th131: H 18thTable 319-1Autoantibodies in Systemic Lupus Erythematosus SLEAntibodyPrevalence, Clinical UtilityAntinuclear antibodies98Best screening test; repeated negative tests make SLE unlikelyAnti-dsDNA70High titers are SLE-specific and in some patients correlate with disease activity, nephritis, vasculitisAnti-Sm25Specific for SLE; no definite clinical correlations; most patients also have anti-RNP; more common in blacks and Asians than whitesAnti-RNP40Not specific for SLE; high titers associated with syndromes that have overlap features of several rheumatic syndromes.Anti-Ro SS-A30Not specific for SLE; associated with sicca syndrome, predisposes to subacutecutaneous lupus, and to neonatal lupus with congenital heart block; associated with decreased risk for nephritisAnti-La SS-B10Usually associated with anti-Ro; associated with decreased risk for nephritisAntihistone70More frequent in drug-induced lupus than in SLEAntiphospholipid50Three tests available-ELISAs for cardiolipin and P 2G1, sensitive prothrombin time Dilute Russell Viper Venom Time DRVVT; predisposes to clotting, fetal loss, thrombocytopeniaAntierythrocyte60Measured as direct Coombs test; a small proportion develops overt hemolysisAntiplatelet30Associated with thrombocytopenia but sensitivity and specificity are not good; this is not a useful clinical testAntineuronal includes anti-glutamate receptor60In some series a positive test in CSF correlates with active CNS lupus.Antiribosomal P20In some series a positive test in serum correlates with depression or psychosis due to CNS lupusAlso remember: AutoantibodyAssociated disorder1Anti-IgG rheumatoid factorRheumatoid arthritis2AnticentromereScleroderma CREST3Anti-Scl-70Scleroderma diffuse4AntimitochondrialPrimary biliary cirrhosis5Antigiiadin , Anti-glutaminase, Anti-reticulinCeliac disease6Anti-basement membraneGoodpastures syndrome7Anti-epithelial cellPemphigus vulgaris8Antimicrosomal, antithyroglobulinHashimotos thyroiditis9Anti-Jo-1Polymyositis, dermatomyositis10Anti-SS-A anti-RoSjogrens syndrome11Anti-SS-B anti-LaSjogrens syndrome12Anti-Ul RNP ribonucleoproteinMixed connective tissue disease13Anti-smooth muscleAutoimmune hepatitis14Anti-glutamate decarboxylaseType 1 diabetes mellitus15c-ANCAWegeners granulomatosis16p-ANCAOther vasculitides17Antisaccharomyces cervicaeCrohns disease18Anti-kuSLE 