Complement 3 deficiency

Complement 3 deficiency is a genetic condition affecting complement component 3, abbreviated C3. People can suffer from either a primary or a secondary form. Primary C3 deficiency is an inherited autosomal recessive disorder involving mutations in the gene for C3. Secondary C3 deficiency results from a lack of factor I or factor H, two proteins that are key for the regulation of C3. Both forms are characterised by low levels or absence of C3. This is a single named deficiency, separate from the broader group of complement deficiencies. This entry records what the source lead supports and is not medical advice; features, infections and treatment are left for later depth work.