| A rare genetic primary immunodeficiency disease with characteristics of increased susceptibility to recurrent usually severe infections (particularly by Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumonia), typically manifesting as otitis, sinusitis, bronchitis, pneumonia, and/or meningitis. Autoimmune disease (for example systemic lupus erythematosus, glomerulonephritis) and atypical hemolytic uremic syndrome may be associated. Laboratory serum analysis reveals, in addition to diminished or undetectable complement factor I, variably decreased complement C3, complement factor B and complement factor H. Caused by homozygous or compound heterozygous mutation in the gene encoding complement factor I on chromosome 4q25. |
