HUS Foundation

Atypical Hemolytic Uremic Syndrome

Atypical Hemolytic Uremic Syndrome (AHUS) is an exceedingly uncommon group of disorders of the kidneys. It is a clearly distinct sickness from Hemolytic Uremic Syndrome. The syndrome is not caused by a foreign broker (such as a bacterium, virus etc). Instead, some sort of internal chain of events sets the Hemolytic Uremic Syndrome off, and the syndrome becomes active. It is believed that a majority of the cases are genetic in origin. There are four genes associated with this disorder. They are Factor H, Factor I, Factor B and MCP. The first three genes are responsible for producing proteins that originate in the liver. The fourth, MCP, is not synthesized in the liver, but rather is a protective coating that lines the kidneys. All four factors cause a problem in the complement system, which ends up damaging the endothelium. The kidney is the organ that seems especially susceptible to these problems.

Atypical Hemolytic Uremic Syndrome (AHUS) may become a chronic condition, and patients with this syndrome may experience repeated attacks of the disorder. In either case, Atypical Hemolytic Uremic Syndrome patients have many of the same symptoms as typical Hemolytic Uremic Syndrome patients. However, there are quite a number of differences. While the Typical form of the disease may start off more severe, the Atypical form is subject to longer lingering effects, and is much more likely to become a chronic problem. Recurrence is much more common with the Atypical form of the disease. Children with Atypical Hemolytic Uremic Syndrome are much more likely to develop chronic serious complications such as kidney failure and severe high blood pressure.

Helpful Links
National Center for Biotechnology Information
Cigna Health Info
E Medicine
Atypical HUS Website
Gene Reviews
PubMed
Kidney Advocate
New England Journal of Medicine - Alexion to Begin Clinical Trials of Soliris® in aHUS Patients
Blood - Disorders of Red Cell Regulation and Production