Hartnup disease

Sep 14
14:12

2008

Juliet Cohen

Juliet Cohen

  • Share this article on Facebook
  • Share this article on Twitter
  • Share this article on Linkedin

Hartnup disease may be marked by skin problems, coordination impairment, vision problems, mild mental retardation, gastrointestinal problems, and central nervous system abnormalities.

mediaimage

Hartnup disorder is an inherited metabolic disorder involving the transport of certain amino acids (for example,Hartnup disease Articles tryptophan and histidine) in the small intestine and kidneys. Hartnup disease is classified in the group of the Neutral Aminoacidurias, since the amino acids lost in the urine are the so called neutral amino acids : tryptophan, alanine, asparagine, glutamine, histidine,isoleucine, leucine, phenylalanine, serine, threonine, tyrosine and valine. Factors that may precipitate acute attacks of this disorder may include poor nutrition, exposure to sunlight, sulphonamide medications and/or psychological stress.

Symptoms may begin in infancy or early childhood, but sometimes they begin as late as early adulthood. Symptoms may be triggered by sunlight, fever, drugs, or emotional or physical stress. A period of poor nutrition nearly always precedes an attack. The attacks usually become progressively less frequent with age. The majority of people with this disorder do not show any symptoms. About 10-20% of people with Hartnup disease do have symptoms.

Most symptoms occur sporadically and are caused by a deficiency of niacinamide. A rash develops on parts of the body exposed to the sun. Mental retardation, short stature, headaches, an unsteady gait, and collapsing or fainting are common. Psychologic problems (such as anxiety, rapid mood changes, delusions, and hallucinations) may also result. Poor nutrition frequently precedes an attack of symptoms. The frequency of attacks usually decreases as the patient gets older.

People with Hartnup disease can prevent attacks by maintaining good nutrition and supplementing their diet with niacinamide or niacin, a B-complex vitamin very similar to niacinamide. A diet that is adequate in protein can overcome the deficiency caused by poor intestinal absorption and excess excretion of amino acids into the urine. Some patients may require dietary supplements of tryptophan. Eating a healthy, high protein diet can relieve the symptoms and prevent them from recurring. Hartnup disease is an inherited condition. Parents may not have the disease themselves, but may pass the genes responsible for it on to their children. Genetic testing can be used to identify carriers of the genes.