Information On Phenylketonuria, Causes Of Phenylketonuria, Symptoms Of Phenylketonuria, Diagnosis Of Phenylketonuria, Treatment Of Phenylketonuria

INFORMATION ON PHENYLKETONURIA

Phenylketonuria is an inherited error of metabolism caused by a deficiency in the enzyme phenylalanine hydroxylase. Loss of this enzyme results in mental retardation, organ damage, and unusual posture and can, in cases of maternal phenylketonuria, severely compromise pregnancy. Phenylketonuria is a genetic disorder that is characterized by an inability of the body to utilize the essential amino acid, phenylalanine. This disorder can cause brain damage and progressive mental retardation as a result of the accumulation of phenylalanine and its breakdown products.

SYNONYMS OF PHENYLKETONURIA

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CAUSES OF PHENYLKETONURIA

Phenylketonuria is an inherited disease which passes on over generation. These disorders may be caused by a partial deficiency of the phenylalanine breakdown enzyme or the lack of another enzyme important to the processing of this amino acid. Chronically high levels of phenylalanine and some of its breakdown products can cause significant brain problems.

SYMPTOMS OF PHENYLKETONURIA

Symptoms of phenylketonuria: Mental retardation may develop gradually and may not be evident for a few months. An early clue to the disease is light coloring of the skin, eczema, and a musty odor. Infants with phenylketonuria may be lethargic, feed poorly, and have a "mousy" odor from their sweat and urine. Eczema, sensitivity to sunlight, and light skin are also characteristic of phenylketonuria. Symptoms of children with untreated phenylketonuria include significantly diminished mental capacity, hyperactivity, and seizures. Many have blue eyes and fairer hair and skin than other family members. Currently, most symptoms of untreated phenylketonuria are avoided by newborn screening, early identification, and management.

DIAGNOSIS OF PHENYLKETONURIA

The problem can be removed in birth days from a small blood sample the Guthrie heel prick test, so screening for phenylketonuria is done routinely in most industrialized countries, usually combined with testing thyroid function and other genetic disorders of metabolism. A sustained rise in serum phenylalanine levels of greater than 20 mg/dl was observed in 166 infants (85.1%), compatible with the diagnosis of classical PKU. In the remaining 29 infants (14.9%), the serum phenylalanine concentration either did not reach 20 mg/dL or, having achieved this level, subsequently declined below this point by 72 hours. Genotypic analysis could be used for identifying homozygotes in the newborn period, for prenatal diagnosis, or for heterozygote detection in general populations.

TREATMENT OF PHENYLKETONURIA

Treatment includes a diet that is extremely low in phenylalanine, particularly when the child is growing. Strict compliance to the diet is necessary to prevent or minimize mental retardation. This requires close supervision by a registered dietitian or physician, and cooperation of the parent and child. Every state now screens the blood phenylalanine level of all newborns at about 3 days of age. This test is one of several newborn screening tests performed before or soon after discharge from the hospital. Adult women who have phenylalanine and who plan to become pregnant should also adhere to a strict low-phenylalanine diet both before becoming pregnant and throughout the pregnancy.