Cardiac amyloidosis is a subcategory of amyloidosis where there is depositing of the protein amyloid in the cardiac muscle and surrounding tissues. Amyloid, a misfolded and insoluble protein, can become a deposit in the hearts atria, valves, or ventricles. These deposits can cause thickening of different sections of the heart, leading to decreased cardiac function. The overall decrease in cardiac function leads to a plethora of symptoms. This multisystem disease was often misdiagnosed, with diagnosis previously occurring after death during autopsy. However, recent advancements of technologies have increased the diagnosis of the disease. Cardiac amyloidosis has multiple sub-types including light chain, familial, and senile. One of the most studied types is light chain cardiac amyloidosis. Prognosis depends on the extent of the deposits in the body and the type of amyloidosis. New treatment methods are actively being researched in regards to the treatment of heart failure and specific cardiac amyloidosis problems. Types
The multiple subtypes of cardiac amyloidosis have varying epidemiological, diagnostic, and prognostic characteristics. Light chain (AL-CM)
This relatively rare form of cardiac amyloidosis occurs in an estimated six to ten cases per 1,000,000 people. This sub- type usually affects males over the age of 60 and is rapidly progressive. Pathogenesis of this form is due to the aggregation of immunoglobulin lambda light chains. These chains are created by an abnormal expansion of plasma cells. Over time, these light chains deposit into the interstitial tissue within the myocardium.
Urocanic aciduria is an autosomal recessive metabolic disorder caused by a deficiency of the enzyme urocanase. It is a secondary disorder of histidine metabolism. Symptoms and signs
Urocanic aciduria is thought to be relatively benign. Although aggressive behavior and mental retardation have been reported with the disorder, no definitive neurometabolic connection has yet been established. Genetics
Urocanic aciduria has an autosomal recessive inheritance pattern, which means the defective gene is located on an autosome, and two copies of the gene – one copy inherited from each parent – are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but are usually not affected by the disorder. Pathophysiology
The amino acid histidine, when catalyzed by the enzyme histidase, forms urocanic acid. Disruptions in this pathway, caused by a deficiency of histidase, is the underlying cause of histidinemia. This results in reduced levels of skin and serum urocanic acid, the primary indicator of insufficient histidase activity.In urocanic aciduria, increased urocanic acid in the urine indicates a deficiency of the enzyme urocanase.With normal to only slightly elevated levels of histidine present in the liver during urocanic aciduria, the only true metabolic indicator of the disorder can be found in the urine. Diagnosis
Treatment
See also
Inborn errors of metabolism
Imidazole
Aromatic amino acids
Recessive disorders

References


== External links ==