In simple words: This code represents a group of inherited conditions that affect how the body breaks down certain building blocks of DNA and RNA. These conditions can lead to a buildup of harmful substances in the blood and cause problems with the nervous system, blood, and immune system.

Purine (adenine and guanine) and pyrimidine (cytosine and thymine) metabolism disorders refer to inherited metabolic disorders that lead to excess uric acid in the blood (hyperuricemia) from the breakdown of purine or excess ammonia, carbon dioxide, and beta–amino acids from the breakdown of pyrimidine with neurologic, hematologic, and immunologic manifestations. These disorders can affect any system in a variety of ways, often mimicking other more recognizable disorders, sometimes causing major morbidity and mortality.

Example 1: A pediatric patient presents with developmental delay, seizures, and recurrent infections. Laboratory tests reveal elevated uric acid levels and genetic testing confirms a diagnosis of Lesch-Nyhan syndrome (a purine metabolism disorder)., An adult patient experiences severe joint pain, swelling, and redness. Blood tests show high levels of uric acid, but no other signs of inflammatory arthritis. The patient is diagnosed with hyperuricemia without signs of inflammatory arthritis and tophaceous disease., An infant exhibits failure to thrive, vomiting, and lethargy. Metabolic screening reveals elevated ammonia levels, leading to a diagnosis of a urea cycle disorder (which can be related to pyrimidine metabolism).

Documentation should include detailed patient history, family history, physical exam findings, laboratory results (including uric acid, ammonia, and other metabolic markers), genetic testing reports, and imaging studies.