An acute hemolytic transfusion reaction (AHTR), also called immediate hemolytic transfusion reaction, is a life-threatening reaction to receiving a blood transfusion. AHTRs occur within 24 hours of the transfusion and can be triggered by a few milliliters of blood. The reaction is triggered by host antibodies destroying donor red blood cells. AHTR typically occurs when there is an ABO blood group incompatibility, and is most severe when type A donor blood is given to a type O recipient. Signs and symptoms
Early acute hemolytic transfusion reactions are typically characterized by fever, which may be accompanied by rigors (chills). Mild cases are also typically characterized by abdominal, back, flank, or chest pain. More severe cases may be characterized by shortness of breath, low blood pressure, hemoglobinuria, and may progress to shock and disseminated intravascular coagulation. In anesthetized or unconscious patients, hematuria (blood in the urine) may be the first sign of AHTR. Other symptoms include nausea, vomiting, and wheezing. Causes
The most common cause of acute hemolytic transfusion reaction is ABO incompatibility, which is typically due to human error that results in a recipient receiving the incorrect blood product. Rarely, other blood type incompatibilities can cause AHTR, the most common of which is Kidd antigen incompatibility. Rh, Kell, and Duffy antigen incompatibility have also been implicated in AHTR. Mechanism
Antibodies against A and B blood groups (isohemagglutinins) present in the recipients blood destroy the donor red blood cells.
These patients are under the risk of severe hyperammonemia during infections that can lead to comatose states.Liver transplant is gaining a role in the management of these patients, with small series showing improved quality of life. Epidemiology
Propionic acidemia is inherited in an autosomal recessive pattern and is found in about 1 in 35,000 live births in the United States. The condition appears to be more common in Saudi Arabia, with a frequency of about 1 in 3,000. The condition also appears to be common in Amish, Mennonite and other populations with higher frequency of consanguinuity. History
In 1957, a male child was born with poor mental development, repeated attacks of acidosis, and high levels of ketones and glycine in the blood. Upon dietary testing, Dr. Barton Childs discovered that his symptoms worsened when given the amino acids leucine, isoleucine, valine, methionine, and threonine. In 1961, the medical team at Johns Hopkins Hospital in Baltimore, Maryland published the case, calling the disorder ketotic hyperglycinemia. In 1969, using data from the original patients sister, scientists established that propionic acidemia was a recessive disorder, and that propionic acidemia and methylmalonic acidemia are caused by deficiencies in the same enzyme pathway. See also
Methylmalonic acidemia
Isovaleric acidemia
Maple syrup urine disease

References
External links
Propionic acidemia at NLM Genetics Home Reference
Propionic acidemia at NIHs Office of Rare Diseases
"Propionic acidemia". Orphanet.