UrticariaIntestinal Pseudo-ObstructionPurpura, ThrombocytopenicPurpura, Thrombocytopenic, IdiopathicChronic DiseasePrimary MyelofibrosisConstipationPolyneuropathiesBasophil Degranulation TestSplenectomyPlatelet CountJaundice, Chronic IdiopathicAngioedemaDanazolManometryMyeloproliferative DisordersAutoantibodiesBasophilsSkin TestsIdiopathic Pulmonary FibrosisNeutropeniaGastrointestinal MotilityAutoimmune DiseasesJanus Kinase 2BiopsyTreatment OutcomeBone MarrowImmunoglobulin GScoliosisSeverity of Illness IndexArthritis, JuvenileIdiopathic Interstitial PneumoniasPulmonary FibrosisCardiomyopathy, DilatedT-Lymphocytopenia, Idiopathic CD4-PositiveHyperostosis, Diffuse Idiopathic SkeletalPseudotumor CerebriBracesGlomerulonephritis, MembranousLung Diseases, InterstitialMyositisClubfootNephrotic SyndromeRetroperitoneal FibrosisHydrocephalus, Normal PressureHypertension, PulmonaryHemosiderosisCase-Control StudiesRetrospective Studies