$Unique_ID{BRK03799} $Pretitle{} $Title{Hartnup Disease} $Subject{Hartnup Disease H Disease Hart Syndrome Pellagra-Cerebellar Ataxia-Renal Aminoaciduria Syndrome Tryptophan Pyrrolase Deficiency Methylmalonic Aciduria Pellagra} $Volume{} $Log{} Copyright (C) 1987, 1990 National Organization for Rare Disorders, Inc. 347: Hartnup Disease ** IMPORTANT ** It is possible the main title of the article (Hartnup Disease) is not the name you expected. Please check the SYNONYMS listing to find the alternate names, disorder subdivisions, and related disorders covered by this article. Synonyms H Disease Hart Syndrome Pellagra-Cerebellar Ataxia-Renal Aminoaciduria Syndrome Tryptophan Pyrrolase Deficiency Information on the following diseases can be found in the Related Disorders section of this report: Pellagra Methylmalonic Aciduria General Discussion ** REMINDER ** The information contained in the Rare Disease Database is provided for educational purposes only. It should not be used for diagnostic or treatment purposes. If you wish to obtain more information about this disorder, please contact your personal physician and/or the agencies listed in the "Resources" section of this report. Hartnup Disease is a rare metabolic disorder inherited as a recessive trait. It involves an inborn error of amino acid metabolism as well as niacin deficiency. Factors which precipitate attacks of this disorder may include poor nutrition, exposure to sunlight, sulfonamide medications and/or psychological stress. Hartnup Disease may be marked by skin problems, coordination impairment, vision problems, mild mental retardation, and central nervous system abnormalities. Frequency of attacks usually diminish with age. Symptoms Hartnup Disease may be characterized by a red, scaly rash which may occur after exposure to sunlight. Sudden attacks of impaired muscle coordination (ataxia), double vision, and fainting may occur with this disorder. Retarded mental development, short stature, emotional instability, and dementia may also be symptomatic of untreated Hartnup Disease. Mild heart irregularities (arrhythmias) may also occur but are extremely rare. Causes Hartnup Disease is inherited as a recessive trait. It is an inborn error of amino acid metabolism including tryptophan (which affects growth), and the decomposition of these amino acids in the intestines. Precipitating factors in this disorder may include poor nutrition, fever, exposure to sunlight, sulfonamide medications and/or psychological stress. (Human traits including the classic genetic diseases, are the product of the interaction of two genes for that condition, one received from the father and one from the mother. In recessive disorders, the condition does not appear unless a person inherits the same defective gene from each parent. If one receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will show no symptoms. The risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is twenty-five percent. Fifty percent of their children will be carriers, but healthy as described above. Twenty-five percent of their children will receive both normal genes, one from each parent and will be genetically normal.) Affected Population Hartnup Disease usually begins in childhood and continues into adulthood. Like most inborn errors of metabolism, it is very rare. Related Disorders Pellagra is an illness that results from a deficiency of nicotinic acid and occasionally tryptophan. This disorder is marked by lack of appetite (anorexia), weakness, discomfort, emotional instability, insomnia, bouts of diarrhea or constipation, a burning or stinging sensation of the skin (especially following exposure to the sun), and a sore mouth. The skin may become reddish-brown, scaly, and rough. This disorder usually occurs from deficiencies in the diet such as those that occur in countries where corn or maize is the staple food. It is very rare in the United States. Methylmalonic Aciduria is a form of Ketotic Hyperglycinemia. It is due to a malfunction of amino acid metabolism. This disorder may be marked by an accumulation of acid in the blood (acidosis), drowsiness, coma, and mental or physical retardation. Treatment of Methylmalonic Aciduria includes a low-protein diet, amino acids such as isoleucine, valine, and threonine and/ or massive doses of Vitamin B-12. (For more information on Ketotic Hyperglycinemia, choose "hyperglycinemia" as your search term in the Rare Disease Database.) Therapies: Standard Attacks of Hartnup Disease in people affected by this disorder can be reduced or avoided by maintaining good nutrition, supplementing the diet with niacinamide or niacin, and avoiding the sun and sulfonamide drugs. Other treatment is symptomatic and supportive. Genetic counseling may be helpful to affected families. Therapies: Investigational Genetic studies on children born to mothers affected by Hartnup Disease suggest that the abnormal metabolism of amino acids in this disorder does not have an adverse effect on the embryo. Further investigations are necessary to determine the exact biological cause of Hartnup Disease, which could in turn lead to prevention and/or new treatments. This disease entry is based upon medical information available through January 1990. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder. Resources For more information on Hartnup Disease, please contact: National Organization for Rare Disorders (NORD) P.O. Box 8923 New Fairfield, CT 06812-1783 (203) 746-6518 National Digestive Diseases Information Clearinghouse Box NDDIC Bethesda, MD 20892 (301) 468-6344 Research Trust for Metabolic Diseases in Children Golden Gates Lodge, Weston Rd. Crewe CW1 1XN, England Telephone: (0270) 250244 For information on genetics and genetic counseling referrals, please contact: March of Dimes Birth Defects Foundation 1275 Mamaroneck Avenue White Plains, NY 10605 (914) 428-7100 Alliance of Genetic Support Groups 35 Wisconsin Circle, Suite 440 Chevy Chase, MD 20815 (800) 336-GENE (301) 652-5553 References HARTNUP DISEASE. CLINICAL, PATHOLOGICAL, AND BIOCHEMICAL OBSERVATIONS: A.J. Tahmoush, et. al.; Arch Neurol. (Dec. 1976, issue 33(12)). Pp.797-807. MATERNAL HARTNUP DISORDER: B.E. Mahon, et. al.; Am J Med Genet (July 1986, issue 24(3)). Pp.513-518. OCCURRENCES OF METHYLMALONIC ACIDURIA AND HARTNUP DISORDER IN THE SAME FAMILY: V.E. Shih, et. al.; Clin Genet (September 1984, issue 26(3)). Pp. 216-220.