Rare immunodeficiency caused by X-linked inherited properdin deficiency(CFPD) caused by a mutation in the CFP gene (CFP; 300383).
The mutant protein, properdin (factor P), is a plasma protein active in the alternative complement pathway of the innate immune system. It is a positive regulatory factor that binds to many microbial surfaces to stabilize C3b,Bb convertase. Deficiency of Properdin is particularly associated with increased susceptibility to Neisseria species (Janeway et al. 2001).
Gelfand et al (1987) described a 9-year-old boy with recurrent pneumococcal bacteremia. His serum showed no hemolytic activity in either the classical or the alternative complement pathway. The lack of activity in the classical pathway was found to be due to homozygous C2 deficiency. The patient had a marked deficiency of serum properdin. The father's properdin level was normal and the mother's was seminormal, suggesting an X-linked inheritance. Addition of purified properdin to the patient's serum completely restored the function of the alternative pathway.
Fijen et al (1989) presented a family with a very large kinship that had at least 9 affected males in 3 generations and 6 separate siblings. Properdin deficiency was found in 9 of 46 patients. Meningococcal disease had occurred in 5 of 9 patients after the age of 10 years. All were male. C3 deficiency syndromes (see 613799) were noted in 5 patients, and homozygous deficiency of a terminal component (C5, C6, C7, or C8) was noted in 9 patients. The meningococcal diseases studied were due to rare serotypes X, Y, Z, W135, or 29E.