Factor H1 deficiency

Factor H, also known as beta-1H, is a serum glycoprotein that controls the function of the alternative complement pathway and acts as a cofactor with factor I. It regulates the activity of the C3 convertases such as C4b2a. Factor H is synthesized in hepatocytes, macrophages, B cells, endothelial cells, and platelets. Deficiency of factor H leads to uncontrolled activation of the alternative pathway and C3 consumption. Levels of C3 are reduced, and total hemolytic complement activity and alternative pathway complement activity are usually reduced.

Alternative names

Complement factor H deficiency


  • Defects of the alternative complement pathway


Autosomal recessive


+134370 H factor 1; HF1

Cross references

Phenotypically related immunodeficiencies

IDR factfile for C4 binding protein α deficiency


Incidence is not known.