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Nucleic Acid Metabolism Disorders

Pathologia metabolismi acidorum nucleicorum

For medical students2 min readUpdated 2026-10-10

Disorders of nucleic acid metabolism involve pathological alterations in the synthesis and degradation of purine and pyrimidine bases. These processes lead to severe metabolic disruptions, including hemolytic anemia, gout, and toxic acid accumulation.

Metabolic BasicsInvolves the metabolism of purine and pyrimidine compounds
Megaloblastic AnemiaA frequent severe complication in pyrimidine metabolism disorders
Uric AcidThe final product of purine catabolism in the body
GoutA key pathological manifestation of purine metabolism disorders

General Characteristics of Metabolic Disruptions

Pathologies of nucleic acid metabolism are based on primary disorders in the synthesis and subsequent degradation reactions of purine and pyrimidine bases. These compounds play a fundamental role in maintaining normal body function by supporting DNA, RNA, as well as key nucleotide triphosphates and pyrophosphates. Any disruptions in these pathways inevitably impact cellular metabolism.

Pyrimidine Base Metabolism Disorders

Major pyrimidine structures include uracil, thymine, cytosine, as well as methyl- and hydroxymethylcytosine.

Main pathological conditions in this group:

  1. Hemolytic anemia — a systemic hematological disorder.
  2. Aminoisobutyric aciduria — a condition developing due to a deficiency of the enzyme 3-hydroxyisobutyrate dehydrogenase.
  3. Orotic acidemia and orotic aciduria — pathologies with an autosomal recessive inheritance pattern. The pathogenesis involves a block in the conversion of orotic acid to cytidylic acid. This causes excessive accumulation of the acid in tissues and its excretion in urine, and also provokes severe megaloblastic anemia.

Purine Base Metabolism Disorders

The purine group is represented by substances such as adenine, guanine, methyladenine, and methylguanine. In addition to participating in the structure of nucleic acids, they are components of essential high-energy compounds, including ATP, ADP, GTP, and GDP.

The final product of purine degradation is uric acid. Disorders in this metabolic branch manifest as:

Frequently asked questions

Deficiency of which enzyme is the cause of Lesch-Nyhan syndrome?

The cause of Lesch-Nyhan syndrome is a deficiency of the enzyme hypoxanthine-guanine phosphoribosyltransferase (also known as HGPRT). Complete lack of this enzyme's activity leads to a disruption of the purine salvage pathway.

Consequences of the enzyme deficiency:

  • Purine oxidation — hypoxanthine and guanine cannot be reused and are converted into uric acid, causing hyperuricemia and neurotoxicity.
  • PRPP accumulation — excess phosphoribosyl pyrophosphate activates de novo purine synthesis, further increasing uric acid production.
Which enzyme catalyzes the conversion of hypoxanthine to uric acid?

The conversion of hypoxanthine to uric acid is catalyzed by the enzyme xanthine oxidase. This key enzyme of purine metabolism ensures the sequential oxidation of substrates.

The process of uric acid formation occurs in stages:

  • First reaction — the conversion of hypoxanthine to xanthine by xanthine oxidase.
  • Second reaction — further oxidation of xanthine to uric acid by the same enzyme.

This process predominantly occurs in hepatocytes and enterocytes, completing the metabolism of purine bases.

What is the final product of purine metabolism?

The final metabolite of purine metabolism in the human body is uric acid.

What inheritance pattern is characteristic of orotic acidemia?

This pathology is inherited in an autosomal recessive manner.

What complication frequently accompanies orotic acidemia?

Severe megaloblastic anemia frequently develops against the background of orotic acidemia and orotic aciduria.

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