ANA: antinuclear antibody; anti-dsDNA: anti-double-stranded DNA; BUN: blood urea nitrogen; LDH: lactate dehydrogenase; LH: luteinizing hormone; LCH: Langerhans cell histiocytosis; RDD: Rosai-Dorfman disease; WBC: white blood cells; FSH: follicle-stimulating hormone; ESR: erythrocyte sedimentation rate. The gene discussed is BRD2; the disease is Langerhans cell histiocytosis.