Complement deficiency and disease: an update.
Complement deficiencies are probably vastly under-diagnosed within clinical medicine. Judging from a Swedish study of C2 deficiency, a deficiency with an estimated prevalence of about 1/20,000 in Western countries, less than 10% of the deficiencies of the classical and alternative pathways and the late complement components are identified in Sweden. C1 inhibitor deficiency and deficiencies of MBL and MASP-2 were not included in the assessment. The introduction of new screening methods should facilitate detection of complement deficiencies in clinical practice. In our study of C2 deficiency (n=40), 57% of the patients had a history of invasive infection with encapsulated bacteria, mainly Streptococcus pneumoniae. This emphasizes the importance of the classical and/or the lectin pathway in defence against severe infection. Rheumatological disease, mainly systemic lupus erythematosus was present in 43% of the patients. In addition, a significant association was found between C2 deficiency and atherosclerosis. Complement-dependent disease mechanisms are discussed together with the potential importance of non-complement genes for disease expression in complement deficiencies. Analysis of larger patient groups is required in order to establish guidelines for investigation and treatment of patients with complement deficiency.
Sjöholm
A G
AG
Institute of Laboratory Medicine, Section of Microbiology, Immunology and Glycobiology, Lund University, Sölvegatan 23, SE-221 85 Lund, Sweden. anders.sjoholm@med.lu.se
Jönsson
G
G
Braconier
J H
JH
Sturfelt
G
G
Truedsson
L
L
D050197:Atherosclerosis / Q000453:epidemiology / Q000235:genetics / Q000276:immunology* / Q000628:therapy; D037582:Complement Pathway, Mannose-Binding Lectin / Q000276:immunology*; D003165:Complement System Proteins / Q000172:deficiency* / Q000276:immunology; D016905:Gram-Negative Bacterial Infections / Q000453:epidemiology / Q000235:genetics / Q000276:immunology* / Q000628:therapy; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000453:epidemiology / Q000235:genetics / Q000276:immunology* / Q000628:therapy; D050606:Mannose-Binding Protein-Associated Serine Proteases / Q000172:deficiency* / Q000276:immunology; D013548:Sweden
D003165:Complement System Proteins; C105296:MASP2 protein, human; D050606:Mannose-Binding Protein-Associated Serine Proteases