title: [A congenital deficiency of the C3 fraction of complement. A familial study].
abstract: The innate deficit of the third constituent of the complement is extremely rare, it appears clinically as a deficit of the humorale immunity. We report a case of C3 deficit in a 6 year old Tunisian child, who presents a psychomotor delay and recurrent infections. The investigation of the complement system profile by an immunochemical test of the children's serum shows an absence of C3 and C3d, associated to a loss of classic and alternate hemolytic pathway activities. The addition of functional C3 in the deficient serum restores the global hemolytic activity. The reconstruction of the hemolytic activity is dose dependent of C3 added quantity. The rate of C3 is lowered in the parent's with a 50% decrease of the global hemolytic activity. Immunochemical measurement of C3d confirms the absence of any C3 catabolism product in vivo. On the other hand (factor I) show a normal rate to all the family members.
authors.affiliation: Centre de greffe de moelle, Tunis.
authors.forename: Fayçal
authors.initials: F
authors.lastname: Sassi
authors.forename: Mohamed
authors.initials: M
authors.lastname: Bejaoui
authors.forename: Khaled
authors.initials: K
authors.lastname: Ayed
mesh_terms: D002648:Child; D002657:Child Development / Q000502:physiology; D003176:Complement C3 / Q000172:deficiency* / Q000235:genetics; D015933:Complement C3d / Q000172:deficiency; D006461:Hemolysis / Q000235:genetics; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology
chemical_list: D003176:Complement C3; D015933:Complement C3d