$Unique_ID{BRK04292} $Pretitle{} $Title{Trisomy 18 Syndrome} $Subject{Trisomy 18 Syndrome Trisomy 18 Edward's Syndrome Trisomy E Trisomy 16-18 } $Volume{} $Log{} Copyright (C) 1986, 1992 National Organization for Rare Disorders, Inc. 217: Trisomy 18 Syndrome ** IMPORTANT ** It is possible the main title of the Article (Trisomy 18 Syndrome) is not the name you expected. Please check the SYNONYMS listing to find the alternate names and disorder subdivisions covered by this article. Synonyms Trisomy 18 Edward's Syndrome Trisomy E Trisomy 16-18 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. Trisomy 18 Syndrome is a genetic disorder with onset before birth. Paternal and maternal age are usually above average. Babies appear thin and frail. They fail to thrive and have difficulty feeding. These children show generalized increased muscle tension (hypertonicity) with rigidity in flexion of the limbs and mental retardation. Symptoms The newborn infant with Trisomy 18 is premature or small for its gestational age, with markedly retarded development (hypoplasia) of skeletal muscle and subcutaneous fat. The baby's cry is weak, and response to sound is decreased. There is often a history of feeble fetal activity, excess of fluid in the fetal sac, a small placenta, and a single umbilical artery. The back part of the head is prominent; there is a narrow bifrontal diameter with decreased orbital ridges, short eyelid fissures, a small mouth and unusually small jaw, all of which give the face a pinched appearance. A small head (microcephaly), fold of the eyelid in the lateral corner of the eye (epicanthal folds), low-set malformed ears, and cleft lip and/or palate are common. The peculiar clenched fist with the index finger overlapping the 3rd and 4th fingers is almost distinctive of this disorder. Absence of the distal crease on the 5th finger is common as is a low-arch dermal ridge pattern on the fingertips. The nails are underdeveloped and the big toe is shortened and frequently bent backward (dorsiflexed). Underdeveloped or absent thumbs, clubfeet, rocker-bottom feet, and webbed fingers and toes (syndactyly) may also occur. An opening in the ventricular septum of the heart (ventricular septal defect), persistent blood vessel connecting the aorta to the pulmonary artery (patent ductus arteriosus), an opening in the septum between the two atria in the heart (atrial septal defect), and abnormalities in the pulmonary and/or aortic valves may be present. (For more information on these defects, please see the articles in the Rare Disease Database.) Congenital anomalies of the lung, diaphragm, kidneys and ureters are frequent. Hernias and/or separation of the rectus muscles of the abdominal wall, redundant skin folds especially over the back of the neck, and, in males, failure of the testes to descend into the scrotum are also common. Mental retardation in Trisomy 18 Syndrome is usually severe. Causes Trisomy 18 Syndrome is caused by the presence of a third chromosome 18. This chromosome is responsible for the physical and mental abnormalities of this developmental disorder. Affected Population Female infants are affected 3 times greater than male infants with Trisomy 18 Syndrome. Children with this disorder are generally born to older parents. Therapies: Standard Treatment of Trisomy 18 Syndrome is symptomatic and supportive. Special education, physical therapy, and other medical, social, or vocational services are of benefit to the patient, and are often necessary for the child to reach his/her full potential. Therapies: Investigational This disease entry is based upon medical information available through February 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 Trisomy 18 Syndrome, please contact: National Organization for Rare Disorders (NORD) P.O. Box 8923 New Fairfield, CT 06812-1783 (203) 746-6518 Support Organization for Trisomy 18/13 (SOFT 18/13) National Headquarters 4625 Lindell Blvd., Suite 501 St. Louis, MO 63108 (314) 367-0055 S.O.F.T. Canada Inc. 1214 Concession 5 West RR2 Waterdown, Ontario LOR 2H2 (416) 659-3216 NIH/National Institute of Child Health and Human Development 9000 Rockville Pike Bethesda, MD 20205 (301) 496-5133 Association for Retarded Citizens of the U.S. P.O. Box 6109 Arlington, TX 76005 (817) 640-0204 (800) 433-5252 Mental Retardation Association of America 211 East 300 South, Suite 212 Salt Lake City, UT 84111 (801) 328-1575 In Touch 10 Norman Road Sale, Cheshire M33 3DF Hants, England 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 SMITH'S RECOGNIZABLE PATTERNS OF HUMAN MALFORMATION, 4th ed., Kenneth L. Jones, M.D., W.B. Saunders, Co. 1988. Pp. 16-9.