Phenylalanine, an essential amino acid, is a precursor of tyrosine. It is one of the building blocks of proteins. An increased pile-up of this amino acid in the blood leads to an inborn error of metabolism known as phenylketonuria and further leads to serious health conditions. There are mild and severe forms of PKU. The severe form of PKU, also known as classic PKU, leads to permanent intellectual disability, seizures, and other developmental problems. The excess pile-up of phenylalanine in the body gives a typical mouse-like odor in the body. They also have lighter skin coloration and hair accompanying eczema and other skin disorders. Other variants of this inborn error of metabolism include variant PKU and non-PKU hyperphenylalaninemia. Infants with very high levels of phenylalanine have low birth weight, microcephaly, heart defects, and other intellectual and behavioral problems.

An enzyme known as phenylalanine hydroxylase helps in the conversion of phenylalanine to tyrosine. The deficiency of this enzyme mainly leads to an accumulation of phenylalanine. Instead of getting converted into tyrosine, now, the phenylalanine gets converted into phenylpyruvic acid. Thus, the urine of the individuals suffering from PKU consists of phenylpyruvic acid. PKU mainly occurs at a frequency of 1 in 10,000 individuals and follows the autosomal recessive type of inheritance. The ferric chloride test helps in detecting the phenylpyruvic acid in the urine. Also, the direct fluorometric assays help to determine the excessive amounts of phenylalanine in the blood. Mutation of a gene encoding the enzyme known as phenylalanine hydroxylase mainly leads to the condition. The only option to control the phenylalanine levels in the blood is to reduce or completely avoid the foods rich in phenylalanine amino acid.

Albinism:

An inborn error of metabolism involving little or no production of melanin pigment is known as albinism. Melanin is an important pigment that usually determines the color of the skin, hair, and eyes. This pigment also plays an important role in the optical nerve development. Light skin coloration usually completely whitish skin color is a typical feature of albinism. The hair of these individuals shows a typical white to brown coloration. These individuals have a very light blue to brown eye color. Such individuals also have a very high chance of developing cancer. It is a type of autosomal recessive inheritance and has no cure. They must reduce the sun exposure due to their sensitive skin. A kind of albinism known as oculocutaneous albinism involves the pigment deficiency affecting the eyes, hair, and the skin. An autosomal recessive condition indicates two mutations for the manifestation of the disease phenotype.