Hartnup's disease

This code identifies Hartnup's disease, a rare, inherited metabolic disorder characterized by defective absorption of neutral amino acids, particularly tryptophan, in the small intestine and kidneys. This malabsorption leads to a deficiency of niacin, affecting the central nervous system, skin, and kidneys.

Use this code for patients diagnosed with Hartnup's disease, typically presenting with pellagra-like skin rashes, cerebellar ataxia, psychiatric symptoms, and aminoaciduria. Documentation should confirm the diagnosis through clinical presentation, biochemical testing (e.g., amino acid analysis in urine), and/or genetic testing.

• Ensure documentation clearly distinguishes Hartnup's disease from other amino acid metabolism disorders.
• Code any associated manifestations, such as pellagra or ataxia, separately if they meet criteria for additional coding.
• Genetic testing results confirming the specific gene mutation (SLC6A19) can support this diagnosis.