Items in AFP with MESH term: Genotype
ABSTRACT: Cytochrome P450 enzymes are essential for the metabolism of many medications. Although this class has more than 50 enzymes, six of them metabolize 90 percent of drugs, with the two most significant enzymes being CYP3A4 and CYP2D6. Genetic variability (polymorphism) in these enzymes may influence a patient's response to commonly prescribed drug classes, including beta blockers and antidepressants. Cytochrome P450 enzymes can be inhibited or induced by drugs, resulting in clinically significant drug-drug interactions that can cause unanticipated adverse reactions or therapeutic failures. Interactions with warfarin, antidepressants, antiepileptic drugs, and statins often involve the cytochrome P450 enzymes. Knowledge of the most important drugs metabolized by cytochrome P450 enzymes, as well as the most potent inhibiting and inducing drugs, can help minimize the possibility of adverse drug reactions and interactions. Although genotype tests can determine if a patient has a specific enzyme polymorphism, it has not been determined if routine use of these tests will improve outcomes.
AHA Assesses the Impact of Genotyping on Diagnosis of Genetic Cardiac Disease - Special Medical Reports
Hereditary Hemochromatosis - Article
ABSTRACT: Hereditary hemochromatosis is an autosomal recessive disorder that disrupts the body’s regulation of iron. It is the most common genetic disease in whites. Men have a 24-fold increased rate of iron-overload disease compared with women. Persons who are homozygous for the HFE gene mutation C282Y comprise 85 to 90 percent of phenotypically affected persons. End-organ damage or clinical manifestations of hereditary hemochromatosis occur in approximately 10 percent of persons homozygous for C282Y. Symptoms of hereditary hemochromatosis are nonspecific and typically absent in the early stages. If present, symptoms may include weakness, lethargy, arthralgias, and impotence. Later manifestations include arthralgias, osteoporosis, cirrhosis, hepatocellular cancer, cardiomyopathy, dysrhythmia, diabetes mellitus, and hypogonadism. Diagnosis requires confirmation of increased serum ferritin levels and transferrin saturation, with or without symptoms. Subtyping is based on genotypic expression. Serum ferritin measurement is the most useful prognostic indicator of disease severity. Liver biopsy is performed to stage the degree of fibrosis with severe ferritin elevation or transaminitis, or to diagnose nonclassical hereditary hemochromatosis in patients with other genetic defects. Treatment of hereditary hemochromatosis requires phlebotomy, and the frequency is guided by serial measurements of serum ferritin levels and transferrin saturation. Iron avidity can result from overtreatment. If iron avidity is not suspected, it may mimic undertreatment with persistently elevated transferrin saturation. Dietary modification is generally unnecessary. Universal screening for hereditary hemochromatosis is not recommended, but testing should be performed in first-degree relatives of patients with classical HFE-related hemochromatosis, those with evidence of active liver disease, and patients with abnormal iron study results. Screening for hepatocellular carcinoma is reserved for those with hereditary hemochromatosis and cirrhosis.