Association of high serum concentration of the third component of complement (C3) with pre-existing severe coronary artery disease and new vascular events in women.

Atherosclerosis is an inflammatory disease. The complement system plays an important role in the atherosclerotic process. However, lesser data is available on the possible role of C3 as a risk factor for atherosclerosis.

An age-associated decrease in the frequency of C4B*Q0 indicates that null alleles of complement may affect health or survival.

We studied the distribution of complement C4, C3, and factor B allotypes in 423 healthy Icelandic subjects from 17 to 89 years of age. A marked decrease was observed in the carrier frequency of variant alleles of complement C4B (C4B(*)Q0) and C3 (C3(*)F). These results confirm our previous observations on Hungarian subjects and suggest a negative effect of C4B(*)Q0 on health or survival.