$Unique_ID{BRK03669} $Pretitle{} $Title{Down's Syndrome} $Subject{Down's Syndrome Mongolism Trisomy 21 Syndrome Chromosome 21, Mosiac 21 Syndrome Chromosome 21, Translocation 21 Syndrome Trisomy G Syndrome Chromosome X, Poly X} $Volume{} $Log{} Copyright (C) 1984, 1985, 1987, 1988, 1990, 1992 National Organization for Rare Disorders, Inc. 34: Down's Syndrome ** IMPORTANT ** It is possible that the main title of the article (Down's Syndrome) is not the name you expected. Please check the SYNONYMS listing to find the alternate name and disorder subdivisions covered by this article. Synonyms Mongolism Trisomy 21 Syndrome Chromosome 21, Mosiac 21 Syndrome Chromosome 21, Translocation 21 Syndrome Trisomy G Syndrome Information on the following diseases can be found in the Related Disorders section of this report: Chromosome X, Poly X 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. Down's Syndrome is the most common and readily identifiable genetic condition associated with mental retardation. Facial, skeletal, and frequently cardiac abnormalities are among the more the 50 features seen in this syndrome. It is rare to find all symptoms or even most of them in one person with Down's Syndrome. Symptoms Some common characteristics of Down's Syndrome include an usually small head (microencephaly); a small mouth; a flat nasal bridge; white (Brushfield) spots in the iris of the eyes; a downward slant to the eyes with a fold of skin on the inner corners (epicanthal folds); small ears that may be folded over at the top; a short neck; a transverse (Simian) crease on the palm of the hands; and poor muscle tone (hypotonia). All children with Down's Syndrome have some degree of mental retardation. Generally this retardation is in the mild to moderate range, but sometimes it can be profound. Approximately 50 percent of children with Down's Syndrome have some form of congenital heart disease. They are prone to respiratory, eye, and ear problems. These children are 20 times more likely to develop leukemia than the general population. It is believed that leukemia itself is not inherited but results from an increased genetic susceptibility to environmental factors that may cause leukemia. The life expectancy of people with Down's Syndrome is close to normal. Causes In Down's Syndrome, the mental and physical abnormalities develop due to the presence of an extra chromosome contributed by either the egg or the sperm cell. There are a total of 47 chromosomes instead of the normal 46. Trisomy 21, with three copies of chromosome 21, is the most common form of Down's Syndrome. Affected Population Down's Syndrome occurs in approximately 1 in 800 live births. It is estimated that 7,000 children are born with Down's Syndrome in the United States each year. The incidence is higher for children born to women and men over the age of 35. The most common forms of the syndrome do not usually occur more than once in a family. All races and economic levels are affected equally. Related Disorders Symptoms of the following disorders can be similar to those of Down's Syndrome. Comparisons may be useful for a differential diagnosis: Chromosome X, Poly X Syndrome is a rare chromosomal abnormality that is the result of the presence of extra X chromosome (at least three or four extras). This disorder occurs in females only and the facial features sometimes resemble those of Down's Syndrome. The major features of this condition may include short stature, delayed growth, a short neck, small head (microencephaly), flat nasal bridge, low-set ears and mild to moderate mental retardation. Other features may include eye and ear defects, joint defects and dental abnormalities. (For more information about other disorders characterized by mental retardation, choose "Mental Retardation" as your search term on the Rare Disease Database). Therapies: Standard Down's Syndrome and its basic features cannot be altered. However, children with Down's Syndrome can benefit from early intervention programs such as those recommended by the Association for Retarded Citizens (ARC) and the Association for Children with Down's Syndrome, and other agencies listed in the "Resources" section of this report. Parent and infant education can begin immediately after birth. The individual child receives direct service programming to develop learning, language, mobility, self care and socialization skills. Toddler and preschool programs further enhance the acquisition of skills to enable people with Down's Syndrome to reach their maximum potential. Heart defects may require surgery during infancy or childhood. Prenatal tests are available to determine whether a fetus has Down's Syndrome before birth. Therapies: Investigational Down's Syndrome, as well as other similar disorders, are the focus of ongoing scientific investigations. Studies are underway to determine the complex structure of chromosomes and the genes that are contained in all chromosomes, including chromosome 21. This disease entry is based upon medical information available through October 1992. 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 Down's syndrome, please contact: National Organization for Rare Disorders (NORD) P.O. Box 8923 New Fairfield, CT 06812-1783 (203) 746-6518 Association for Children with Down's Syndrome 2616 Martin Avenue Bellmore, NY 11710 (516) 221-4700 National Down's Syndrome Congress 1640 West Roosevelt Road Chicago, IL 60608 (312) 226-0416 (800) 446-3835 National Association for Down's Syndrome P.O. Box 63 Oak Park, IL 60303 (312) 325-9112 National Down's Syndrome Society 70 West 40th Street New York, NY 10018 (212) 765-3070 (800) 221-4602 National Center for Down's Syndrome 9 Westbourne Road EDG Baston Birmingham, B-15, England (021) 454-3126 NIH/National Institute of Child Health and Human Development (NICHD) 9000 Rockville Pike Bethesda, MD 20892 (301) 496-5133 National Association for Retarded Citizens of the U.S. (ARC) P.O. Box 6109 Arlington, TX 76005 (817) 640-0204 (800) 433-5255 National Institute of Mental Retardation (Canadian Association for the Mentally Retarded) York University Kinsmen NIMR Building 4700 Keele Street Downsview, Ontario M3J 1P3 Canada (416) 661-9611 For Genetic Information and Genetic Counseling Referrals: 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 SMITH'S RECOGNIZABLE PATTERNS OF HUMAN MALFORMATION, 4th ed., Kenneth L. Jones, M.D., W.B. Saunders, Co. 1988. Pp. 10-12, 13-15. THE MERCK MANUAL 15th ed: R. Berkow, et al: eds; Merck, Sharp & Dohme Research Laboratories, 1987. Pp. 167-70. BIRTH DEFECTS ENCYCLOPEDIA, Mary Louise Buyse, M.D., Editor-In-Chief; Blackwell Scientific Publications, 1990. Pp. 391-392. NELSON TEXTBOOK OF PEDIATRICS, 14TH Ed.; Richard E. Behrman, Editors; W.B. Saunders Company, 1991. Pp. 282-284. CLINICAL ASPECTS OF DOWN SYNDROME FROM INFANCY TO ADULTHOOD, S.M. Pueschel; Am J Med Genet Suppl (1990; 7): Pp. 52-56.