Atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome
Synonyms	aHUS
Pronounce	N/A
Specialty	N/A
Symptoms	Hemolytic anemia, Thrombocytopenia, Acute kidney injury
Complications	Chronic kidney disease, End-stage renal disease, Hypertension
Onset	Any age, often in childhood
Duration	Chronic
Types	N/A
Causes	Genetic mutations affecting the complement system
Risks	Family history, certain genetic mutations
Diagnosis	Clinical evaluation, blood tests, genetic testing
Differential diagnosis	Typical hemolytic uremic syndrome, Thrombotic thrombocytopenic purpura
Prevention	N/A
Treatment	Eculizumab, Plasma exchange, Kidney transplantation
Medication	N/A
Prognosis	Variable, depends on treatment and genetic factors
Frequency	Rare
Deaths	N/A

Atypical hemolytic uremic syndrome (aHUS) is a rare, life-threatening, genetic disease that predominantly affects the kidney. It is characterized by the triad of hemolytic anemia, thrombocytopenia, and renal failure.

Etiology

aHUS is primarily caused by mutations in genes that regulate the complement system, a part of the body's immune system. The most common mutations are found in the genes for Factor H, Factor I, and Membrane Cofactor Protein (MCP). These mutations lead to uncontrolled activation of the complement system, resulting in damage to the endothelial cells lining the blood vessels, particularly in the kidneys.

Clinical Presentation

Patients with aHUS often present with symptoms of fatigue, pallor, and decreased urine output, indicative of anemia and renal failure. Laboratory findings typically show evidence of hemolytic anemia, thrombocytopenia, and elevated creatinine levels, reflecting kidney damage.

Diagnosis

Diagnosis of aHUS is based on clinical presentation, laboratory findings, and genetic testing. It is important to differentiate aHUS from other forms of Thrombotic Microangiopathies (TMAs), such as Shiga toxin-producing E. coli Hemolytic Uremic Syndrome (STEC-HUS) and Thrombotic Thrombocytopenic Purpura (TTP), as the treatment and prognosis differ significantly.

Treatment

The mainstay of treatment for aHUS is Eculizumab, a monoclonal antibody that inhibits the terminal complement pathway. This drug has been shown to improve renal function and hematologic parameters in patients with aHUS. In severe cases, renal transplantation may be considered.

Prognosis

Without treatment, aHUS can lead to end-stage renal disease and is associated with high mortality. However, with early diagnosis and appropriate treatment, the prognosis can be significantly improved.

See Also

• Hemolytic Uremic Syndrome
• Thrombotic Microangiopathies
• Complement System
• Eculizumab

NIH genetic and rare disease info

• NIH info on Atypical hemolytic uremic syndrome

Atypical hemolytic uremic syndrome is a rare disease.