High-incidence of C9 deficiency throughout Japan: there are no significant differences in incidence among eight areas of Japan

Int Arch Allergy Appl Immunol. 1989;90(4):400-4. doi: 10.1159/000235061.


From 92,686 sera sent from hospitals throughout Japan to the Special Reference Laboratories for CH50 assay, we were able to classify 80 patients as C9-deficient using a sensitive screening test, as well as hemolytic and immunochemical C9 assays. The incidence of C9 deficiency was determined to be 0.086%, and there were no distinct differences among the eight areas of Japan tested. Serum CH50 levels of these C9-deficient patients varied widely (9.4-63.8 U/ml), and exhibited a higher value (average: 34.1 U/ml) than that of healthy C9-deficient individuals, probably due to elevated C3, C4, and C5 levels. These patients suffered from a variety of autoimmune, renal, and infectious diseases, which, however, are thought to be only incidentally associated with C9 deficiency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Complement C9 / deficiency*
  • Complement Hemolytic Activity Assay
  • Geography
  • Humans
  • Japan


  • Complement C9