HEREDITARY PROPERDIN DEFICIENCY IN 3 FAMILIES OF TUNISIAN JEWS

Hereditary properdin deficiency is a rare genetic disorder of the comp lement system. Three propositi and six additional family members with properdin deficiency have been found following analysis of the hemolyt ic activity of the classical (CH50) and the alternative (AP50) complem ent pathways in the sera of 101 survivors of meningococcal infections and 59 survivors of severe pneumococcal and Haemophilus influenza infe ctions. All the properdin-deficient individuals had undetectable level s of properdin by radial immunodiffusion and by Western blotting. They belonged to three non-related families of Tunisian Jews who came from different parts of Tunisia. Two patients had a meningococcal infectio n at 15 and 16 years of age, respectively, and one had Haemophilus inf luenza meningitis at 1.5 years of age. In contrast to the fulminant an d fatal course of meningococcal infection which was previously describ ed in some properdin-deficient patients, our patients had a relatively mild disease. Properdin deficiency may not be as rare as previously t hought. Analysis of AP50, in addition to CH50, in sera of patients who had meningococcal infection, will probably disclose many more cases o f hereditary properdin deficiency. In addition, our findings indicate that, as in other complement abnormalities, hereditary properdin defic iency may also be associated with the ethnic origin of the patient.