How is Hartnup Disease diagnosed?

Hartnup Disease is a rare genetic disorder that affects the body's ability to absorb certain amino acids, particularly tryptophan. This condition is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene, one from each parent, to develop the disease.

Diagnosing Hartnup Disease typically involves a combination of clinical evaluation, laboratory tests, and genetic testing. The initial step is to assess the patient's medical history and symptoms. Common signs of Hartnup Disease include skin rashes, neurological symptoms, and episodes of aminoaciduria (excretion of amino acids in the urine).

Urine tests play a crucial role in the diagnosis of Hartnup Disease. A 24-hour urine collection is performed to measure the levels of amino acids, particularly tryptophan, in the urine. Individuals with Hartnup Disease often exhibit low levels of tryptophan in their urine due to impaired absorption.

Further blood tests may be conducted to confirm the diagnosis. These tests measure the levels of amino acids in the blood, including tryptophan. Low levels of tryptophan in the blood can indicate Hartnup Disease.

In some cases, genetic testing may be recommended to identify specific mutations in the SLC6A19 gene, which is responsible for encoding the protein involved in amino acid transport. Genetic testing can confirm the diagnosis and help determine if an individual is a carrier of the mutated gene.

It is important to note that the symptoms of Hartnup Disease can vary widely among affected individuals, and some individuals may have mild or atypical symptoms. Therefore, a comprehensive evaluation by a healthcare professional is crucial for an accurate diagnosis.

Once diagnosed, individuals with Hartnup Disease can receive appropriate management and treatment, which typically involves dietary modifications and supplementation with nicotinamide and tryptophan to alleviate symptoms and prevent complications.