the gene that codes for C1-inhibitor, SERPING1, may also play a role in the development of age-related macular degeneration. At least 97 disease-causing mutations in this gene have been discovered. Despite uncontrolled auto-activation, it is important to note that levels of key complement components are low during an acute attack because they are being consumed - indeed, low levels of C4 are a key diagnostic test for hereditary angioedema. This situation is analogous to the low levels of clotting factors found in disseminated intravascular coagulation (DIC). Medical use Hereditary angioedema Blood-derived C1-inhibitor is effective but does carry the risk associated with the use of any human blood product. Cinryze, a pharmaceutical-grade C1-inhibitor, was approved for the use of HAE in 2008 in the US after having been available in Europe for decades. It is a highly purified, pasteurized and nanofiltered plasma-derived C1 esterase inhibitor product; it has been approved for routine prophylaxis against angioedema attacks in adolescent and adult patients with HAE. A recombinant C1-inhibitor obtained from the milk of transgenic rabbits, conestat alfa (trade name Ruconest), is approved for the treatment of acute HAE attacks in adults. While C1-inhibitor therapy has been used acutely for more than 35 years in Europe in patients with C1-inhibitor deficiency, new methods of treating acute attacks have emerged: a plasma kallikrein inhibitor and the bradykinin receptor antagonist icatibant. Other products also have been introduced including plasma-derived products such as Berinert and Haegarda. For other conditions The activation of the complement cascade can cause damage to cells, therefore the inhibition of the complement cascade can work as a medicine in certain conditions. When someone has a heart attack, for instance, the lack of oxygen in heart cells causes necrosis in heart cells: Dying heart cells spill their contents in the extracellular environment, which triggers the complement cascade. Activation of the complement cascade attracts phagocytes that leak peroxide and other reagents, which may increase the damage for the surviving heart cells. Inhibition of the complement cascade can decrease this damage. Synthesis C1-inhibitor is contained in the human blood; it can, therefore, be isolated from donated blood. Risks of infectious disease transmission (viruses, prions, etc.) and relative expense of isolation prevented widespread use. It is also possible to produce it by recombinant technology, but Escherichia coli (the most commonly used organism for this purpose) lacks the eukaryotic ability to glycosylate proteins; as C1-inhibitor is particularly heavily