The present invention provides: an antisense oligonucleotide having CFB expression-suppressing activity； a pharmaceutical composition including the antisense oligonucleotide； and a drug that suppresses the expression of CFB including the antisense oligonucleotide, the drug preventing or treating disorders mediated by abnormalities of the complement alternative pathway such as atypical hemolytic uremic syndrome, paroxysmal nocturnal hemoglobinuria, age-related macular degeneration, membranous-proliferative glomerulonephritis, C3 nephritis, membranous nephropathy, rapid progressive glomerulonephritis (RPGN), acute kidney injury (AKI), asthma, or autoimmune diseases.本發明提供一種具有CFB之表現抑制活性之反義寡核苷酸、含有該反義寡核苷酸之醫藥組合物、以及含有該反義寡核苷酸之抑制CFB之表現且預防或治療非典型溶血性尿毒症症候群、陣發性夜間血紅素尿症、老年性黃斑變性症、膜性增殖性腎小球腎炎、C3腎炎、膜性腎病、急進性腎小球腎炎(RPGN)、急性腎損傷(AKI)、哮喘或自體免疫疾病等由補體旁路途徑之異常所介導之障礙的藥物。
