Phenylalanine is an essential amino acid used as a building block for proteins and enzymes in your body. Phenylalanine is a precursor to many neurotransmitters in the brain, including dopamine. Phenylketonuria is an inherited disorder that prevents your body from processing phenylalanine. If undiscovered, PKU often results in severe developmental retardation. Normally detected within 72 hours after birth, PKU is managed with a specialized diet and avoiding foods with large amounts of phenylalanine.
About Phenylalanine
L-phenylalanine is an essential amino acid that must be acquired from your diet, as your body cannot synthesize it from other amino acids or nutrients. L-phenylalanine is used to produce another amino acid L-tryptophan that is used to synthesize neurotransmitters such as dopamine, norepinephrine, epinephrine as well as thyroid hormones.
About Phenylketonuria
Phenylketonuria is a recessive genetic disorder where the genetic code required to make enzymes that process phenylalanine is defective. Both parents must pass on the defective gene for PKU to arise in a child. Phenylalanine and several metabolites build up in the body causing damage to the nervous system. Phenylalanine is used in the production of pigments; Children with PKU typically have lighter skin and hair. Those with PKU may also show symptoms including a small head size, delayed neurological development, unusual movements, hyperactivity and seizures.
Detection
In developed nations, a test for PKU is usually performed within the first few days following birth. Tests for the mutation that causes PKU may also be performed on both parents at the beginning of pregnancy. It is also possible to sample chorionic tissue for the genetic test to determine if a child has PKU prior to birth. If either a mother or child has PKU it is important to follow a low-phenylalanine diet during pregnancy.
Avoiding Phenylalanine
Foods including meat, chicken, fish, eggs, dairy and soybeans are high in phenylalanine. The artificial sweetener aspartame is also very high in phenylalanine. It is necessary to avoid these foods after a PKU diagnosis, especially while a child is developing. L-tyrosine supplements are commonly taken in order to provide raw materials to produce neurotransmitters. Long-chain omega-3 fatty acids absent in a phenylalanine-free diet is often supplemented from fish oil for normal neurological development.
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