Hartnup Disease
Pathogenesis (Amino Acid Disorder)
- B0AT1 protein inactivity results in failure of amino acid absorption in the intestine and kidneys, which results in amino acid deficiency and thus vitamin and protein deficiency (namely, Tryptophan & Niacin), and manifests with aminoaciduria, most notably, if properly treated.
Clinical
- Systemic manifestations: Aminoaciduria and Tryptophan & Niacin Deficiencies result in – Rash, Episodic psychosis triggered by physiological stress (infection, fasting, etc…): "Pellagra-like dermatosis".
- Neurological manifestations: Ataxia, nystagmus, tremor
- Treatment: Well-balanced diet to make up for poor absorption of amino acids.
Genetics
- SLC6A19 gene mutation
- Autosomal recessive
References
- Calvo, Sherri; Collins, Heather; Greenberg, Kathleen, et. al at US National Library of Medicine, Genetics Home Reference. https://ghr.nlm.nih.gov