Diseases Studied
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All Diseases > Complement mediated thrombotic microangiopathy
Complement mediated thrombotic microangiopathy
Alternative Names: CM-TMA
Disease Category: Thrombotic Microangiopathies
Complement mediated thrombotic microangiopathy (also called atypical hemolytic uremic syndrome) is a disease that causes abnormal blood clots to form in small blood vessels in multiple organs but especially in the kidneys. These clots can cause serious medical problems such as kidney failure or even stroke and heart failure. It can occur at any age and is often caused by a combination of environmental and genetic factors. Genetic factors involve genes that code for proteins that help control the complement system (part of your body's immune system). Environmental factors include certain medications (such as anticancer drugs), chronic diseases (e.g., systemic sclerosis and malignant hypertension), viral or bacterial infections, cancers, organ transplantation, and pregnancy. In about 60% of aHUS, a genetic change may be identified. The genes associated with genetic aHUS include C3, CD46 (MCP), CFB, CFH, CFHR1, CFHR3, CFHR4, CFI, DGKE, and THBD. Genetic changes in these genes increase the likelihood (predisposition) to developing aHUS, rather than directly causing the disease. In most cases, there is no family history of the disease. In cases that do run in families, predisposition to complement mediated TMA is inherited in an autosomal dominant or an autosomal recessive pattern of inheritance. However, having this genetic predisposition translates into disease in only 1 in 5 individuals.