PKU probability problem

PKU (phenylketonuria), in its “classic” form, is a rare, inherited metabolic disease that results in mental retardation and other neurological problems when treatment is not started within the first few weeks of life. When treatment is begun early and well-maintained, affected children can expect normal development and a normal life span. (Not all elevations of blood phenylalanine require treatment; any child with a level less than 6 mg/dl does not need to be on a special diet and is not risk for mental retardation.) Until recently, the only treatment was a very strict diet that limits the amino acid, phenylalanine. Now, however, there is a drug called Kuvan that can help in some cases. The Enzyme Deficiency The disease arises from the absence of a single enzyme called phenylalanine hydroxylase. This enzyme normally converts the essential amino acid, phenylalanine, to another amino acid, tyrosine. Failure of the conversion to take place results in a buildup of phenylalanine. Through a mechanism that is not well understood, the excess phenylalanine is toxic to the central nervous system and causes the severe problems normally associated with PKU. Not every child has the same degree of enzyme deficiency and thus the treatment for each child has to be individualized. The nature of the treatment for an individual child must be determined by an experienced PKU treatment program. Genetics PKU is carried through an “autosomal recessive“ gene. This means that two people who conceive a child must both be “silent carriers“ of the gene in order for there to be a chance that the baby will have PKU. When two carriers conceive a child, there is a one in four (or 25%) chance for each pregnancy that the baby will have PKU. The incidence of carriers in the general population is approximately one in fifty people, but the chance that two carriers will mate is only one in 2500. Carrier tests are available only through PKU treatment programs. Over 500 different genetic mutations have been identified that result in defective functioning of the phenylalanine hydroxylase enzyme, resulting in elevated phenylalanine levels. Each different mutation or combination of mutations results in more or less enzyme activity in the effected person. #ProbabilityMeasurementSystem #PKU #PhenylketonuriaDiseaseOrMedicalCondition #geneticDisorder #DNA #mutation #EnzymeDeficiency #phenylalanine #Tyrosine #AutosomalRecessive #Gene #mutations #phenylalanineHydroxylase #enzyme