Properdin deficiency in a large Swiss family: identification of a stop codon in the properdin gene, and association of meningococcal disease with lack of the IgG2 allotype marker G2m(n).
Three properdin deficiency phenotypes have been reported--complete deficiency (type I), incomplete deficiency (type II), and dysfunction of properdin protein (type III)--all associated with increased susceptibility to meningococcal disease.