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Páginas: 5 (1105 palabras) Publicado: 3 de abril de 2012
Phenylketonuria (PKU) is a genetic disease in which a person cannot properly metabolize an amino acid called phenylalanine (Phe). Amino acids are known as the building block of proteins. Phenylalanine is an amino acid that can only be obtained by eating food because the human body does not produce it. An average healthy person produces an enzyme called phenylalanine hyrdroxylase (PAH) in hisor her body. When the phenylalanine is ingested in the body, it cannot be used by the body, so this enzyme converts phenylalanine into an amino acid called tyrosine, which can be used by the body. People with PKU have a defective PAH and are unable to break down phenylalanine. Since the phenylalanine that is consumed cannot be changed into tyrosine, it builds up in their bodies and it leads toserious health problems.
For a child to inherit PKU, both the mother and the father must have and pass on the defective gene. This pattern of inheritance is called autosomal recessive. It is possible for a parent to have the defective gene, but not have the disease. This is called being a carrier. Most often, PKU is passed on to children by parents who are carriers of the disorder; usually, theydon’t know that they carry the defective gene.
Phenylketonuria was discovered in 1934 by a Norwegian physician named Ivar Asbjorn Folling. In Norway, this disorder is known as Folling’s disease, named after its discoverer. He noticed that several mentally retarded patients had a strange odor in their urine and he figured out




that it was from an organic compound called phenylaceticacid. The patients' urine also had a very high level of a chemical called phenylketone. That is how the disease got its name, phenylketon-uria. Asbjorn Folling thought the disease was most likely inherited, and he was the first doctor to advice using diet to control the disease.
This disease manifests itself in different forms depending on the severity of the PKU. Under these conditions,people with PKU manifests a variety of detrimental traits including mental retardation, seizures, small head size (also known as microcephaly), light coloration (pale skin, blonde hair and blue eyes), foul-smell in the urine and sweat, underdeveloped teeth, hyperactivity, and skin rashes. People with PKU have light coloration because they cannot process phenylalanine into tyrosine which producesmelanin. The most severe form of the disease is known as classical PKU. Children with untreated classical PKU will develop mental retardation. Less severe forms of PKU (sometimes called mild or moderate PKU) have a smaller risk of significant brain damage.
All 50 states in the United States require a PKU screening test for all newborns as part of the newborn screening panel. The test is done bytaking a few drops of blood from the child before it leaves the hospital. Sometimes, a repeat test should be done at nearly two weeks of age. If a newborn is not screened during a routine newborn screening test and have PKU, the disease




may manifest with seizures, albinisms, and a foul odor to the newborn’s sweat and urine. Untreated children are normal at birth, but they are unableto achieve early developmental mile stones at birth. Sometimes, they may develop microcephaly, and they will establish progressive impairment of cerebral function.
Phenylketonuria is a treatable disease. Today, scientists know what foods have phenylalanine in them, and they have created a special diet for people with PKU. This strict diet consists on eating food that contains very lowphenylalanine. Eggs, meat, milk, and cheese are example of foods that contains a lot of phenylalanine and should be avoided. People with PKU cannot consume aspartame. Aspartame is an artificial sweetener that is used to flavor candies and diet sodas. This artificial sweetener contains large amounts of phenylalanine; therefore, it is extremely important not to consume it. People with PKU need to...
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