E72.02

HCC Category Mapping

What This Code Means

A rare inherited disorder affecting the absorption of certain amino acids in the intestines and kidneys, causing neurological symptoms, skin problems, and diarrhea.

Coding Tips

• •Named after the physician who first described it; ensure documentation confirms this specific diagnosis
• •Often presents with photosensitive dermatitis and neuropsychiatric symptoms

Clinical Significance

Hartnup disease is an autosomal recessive disorder of neutral amino acid transport in the kidneys and intestines, caused by mutations in the SLC6A19 gene. The resulting tryptophan malabsorption can cause pellagra-like symptoms including photosensitive dermatitis, cerebellar ataxia, and psychiatric manifestations during metabolic stress. Most affected individuals remain asymptomatic with adequate nutrition, and nicotinamide supplementation effectively prevents symptoms.

Documentation Requirements

• ✓Document urine amino acid analysis showing generalized neutral aminoaciduria, clinical symptoms if present (dermatitis, ataxia, psychiatric changes), genetic testing results, nutritional status assessment, and nicotinamide supplementation regimen.
• ✓Record any triggering factors such as illness, poor nutrition, or sun exposure.

Commonly Confused Codes