E72.02

Clinical Causes: Genetic mutation in the SLC6A19 gene, which encodes a transporter protein responsible for absorbing amino acids in the intestines and reabsorbing them in the kidneys. Inheritance pattern: autosomal recessive, requiring both parents to pass on the defective gene. Environmental factors generally do not cause Hartnup's disease independently, but nutritional deficiencies may exacerbate symptoms.

Key Symptoms: Skin rash, especially around sun-exposed areas (photosensitive dermatitis). Neurological problems such as tremors, ataxia (lack of muscle coordination), and depression. Pellagra-like symptoms, including sudden episodes of dermatitis, diarrhea, and dementia. Intermittent episodes with varying severity, often triggered by environmental factors or nutritional deficiencies. Mild or absent symptoms in some individuals, leading to delayed diagnosis.

Diagnosis Path: Diagnosis of Hartnup's disease involves a combination of clinical evaluation, urine analysis, and genetic testing. Urinalysis typically reveals increased excretion of neutral amino acids, particularly tryptophan, which is indicative of impaired absorption. Confirmation is obtained through genetic testing identifying mutations in the SLC6A19 gene. Additional tests may include blood tests to assess amino acid levels and skin assessments if dermatitis is present.

Treatment Protocols: Management of Hartnup's disease focuses on alleviating symptoms and preventing deficiencies. Treatment strategies may include: - Nutritional supplementation: high-protein diets and supplementation with nicotinic acid (vitamin B3) to support metabolic functions. - Sun protection: use of sunscreens and protective clothing to prevent photosensitive skin rashes. - Medication: niacinamide may help reduce dermatitis symptoms. - Monitoring and addressing neurological symptoms through supportive therapies. - Regular follow-up with healthcare providers to monitor nutritional status and kidney function.