E72.12

HCC Category Mapping

What This Code Means

A genetic deficiency of an enzyme needed to process folate, which can lead to neurological problems and elevated homocysteine levels.

Coding Tips

• •This condition is often treated with folinic acid supplementation; document the treatment approach in the medical record
• •Distinguish from other causes of elevated homocysteine when coding

Clinical Significance

Severe methylenetetrahydrofolate reductase (MTHFR) deficiency is a rare inborn error of folate metabolism causing impaired conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, resulting in homocysteinemia and impaired methionine synthesis. Severe forms present in infancy with neurological deterioration, seizures, and apnea, while milder forms may present later with developmental delay and psychiatric symptoms. This is distinct from the common MTHFR polymorphisms (C677T, A1298C) which are not coded here.

Documentation Requirements

• ✓Document plasma homocysteine levels, methionine levels (typically low, unlike in classical homocystinuria), folate levels, MTHFR enzyme activity or genetic testing confirming severe deficiency, neurological assessment, and treatment regimen (betaine, methionine, folinic acid supplementation).
• ✓Distinguish from common polymorphisms.

Commonly Confused Codes