Hartnup disorder is an inherited metabolic disorder involving the transport of amino acids ( tryptophan ) in the small intestine and kidneys.
Causes, incidence, and risk factors
Hartnup disorder is possibly the most common metabolic condition involving amino acids . It is a genetic disorder inherited in an autosomal recessive manner. Although most people show no symptoms, photosensitivity is the major symptom, and ataxia and mood changes often appear together. The incidence is 1 out of 24,000 people, with the onset usually beginning in childhood.
Signs and tests
A urinalysis checking amino acids (elevated levels of "neutral" amino acids and normal levels of other amino acids) may be done for this disorder.
Treatment
Supplements with nicotinamide is preferred to nicotinic acid as the main treatment. This can effectively treat the rash, and sometimes treat the ataxia and psychiatric symptoms.
A high protein diet is recommended.
Avoiding sun exposure by wearing protective clothing and sunscreen of 15 factor or higher. Psychiatric or neurological treatment if mood swings or psychiatric disease occurs.
Expectations (prognosis)
People with this disorder can expect a normal lifespan with no disability.
Complications
There are usually no complications. The minority of people who develop symptoms can experience rash, ataxia, and less frequently psychiatric symptoms.
Calling your health care provider
Call for an appointment with your health care provider if you have or observe signs or symptoms or have a family history of Hartnup disorder. Genetic counseling is indicated if you have a family history of this condition.
Prevention
There is no known prevention for this rare, inherited condition.