In simple words: This code represents a group of inherited conditions where the body can't break down certain protein building blocks (amino acids) properly.These are called "aromatic" amino acids. Because of this problem, these amino acids build up in the body and may cause problems. Examples include PKU, albinism, and histidinemia.

Aromatic amino-acid metabolism disorders are inborn errors of metabolism characterized by the body's inability to properly break down aromatic amino acids. This leads to an accumulation of these amino acids in the blood and can cause various symptoms depending on the specific disorder. Examples include phenylketonuria (PKU), albinism, and histidinemia.

Example 1: A newborn infant tests positive for phenylketonuria (PKU) on a newborn screening test. The infant is placed on a special low-phenylalanine formula and the diagnosis is confirmed with further testing., A child presents with very pale skin, white hair, and nystagmus (involuntary eye movements). After examination and testing, they are diagnosed with oculocutaneous albinism., An adult undergoes routine bloodwork, which reveals elevated histidine levels. Further evaluation confirms a diagnosis of histidinemia, but the individual is asymptomatic and requires no treatment.

Documentation should include details of the specific disorder, relevant laboratory findings (e.g., amino acid levels, enzyme activity), genetic testing results, and clinical manifestations. For PKU, documentation of dietary management and monitoring of phenylalanine levels is essential.

** This code should not be used to report transitory endocrine and metabolic disorders specific to the newborn (P70-P74).Neoplasms, even if functionally active, are coded in Chapter 2 (Neoplasms), and E70 or related codes can be added to indicate functional activity.