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Copyright 1989, 2003
Triploid Syndrome is an extremely rare chromosomal disorder. Individuals with triploid syndrome have three of every chromosome for a total of sixty-nine rather than the normal forty-six chromosomes. Babies with Triploid Syndrome usually are lost through early miscarriage. However, some infants have been born and survived as long as five months. Affected infants are usually small and have multiple birth defects. Those that survive are usually mosaic, meaning that some cells have the normal number of 46 chromosomes and some cells have a complete extra set of chromosomes.
Triploid Syndrome may include larger than normal size placenta, lack of prenatal skeletal growth, widely spaced eyes (ocular hypertelorism), low nasal bridge, low-set malformed ears and a smaller than normal sized jaw. The third and fourth fingers of the hands may be connected and the hands may have unusual simian creases. The infant may have congenital heart defects and genital abnormalities may be present in males. There may be abnormal brain development, lack of development of the adrenal glands and cystic kidneys. Growth of the brain or spinal cord outside of the body (neural tube defects), openings in the abdominal wall, an unusually shaped skull and cleft lip and/or palate have also been observed. There may also be liver and gallbladder deformities, twisted colon and finger and toe deformities. Individuals who are mosaic will survive longer than those with complete triploidy but usually have mental retardation.
The pregnant mother carrying a triploid fetus sometimes experiences extremes of high blood pressure (hypertension), swelling (edema), and excretion of albumin in the urine (albuminuria). This condition is called toxemia or preeclampsia. Triploidy is frequently diagnosed in pregnancies in which there is a cystic placenta (partial mole). The Triploid Syndrome has been associated with pregnancies that occur soon after oral contraceptives are discontinued or after long menstrual cycles. Triploidy has been reported in conceptions that occurred following in vitro fertilization and in conceptions after a history of repeated miscarriages.
Triploid Syndrome is caused by a complete extra set of chromosomes. The triplication of the chromosomes is most often caused by fertilization of an egg by two sperm. Triploidy can also be caused by fertilization of an egg by a sperm that has an extra set of chromosomes or fertilization of an egg that has an extra set of chromosomes by a normal sperm. This disorder does not run in families and is not associated with maternal or paternal age.
Triploidy occurs slightly more often in males than females.
Symptoms of the following disorders are caused by duplication, triplication or deletion of chromosomes:
Trisomies are very rare genetic disorders characterized by a triple chromosome. The most common symptom of the trisomies is mental retardation. Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males, and two X chromosomes for females. People with a Trisomy have an extra chromosome added to one of the normal pairs. The triplication of the chromosome may be partial, either an extra short arm (p+) or an extra long arm (q+). Defects are classified by the name of the abnormal chromosome pair and which portion of the chromosome is affected. (For more information on this disorder, choose "Trisomy" as your search term in the Rare Disease Database.)
Down Syndrome is the most common and readily identifiable genetic condition caused by a chromosomal abnormality. One additional chromosome is present. Children with Down Syndrome have some degree of mental retardation. That can range from mild to profound. However, most children with Down Syndrome function in the mild to moderate range. Many of the children can be educated in the public schools, learn basic academic and pre-vocational skills with special training, and perform many daily living activities independently. (For more information on this disorder, choose "Down" as your search term in the Rare Disease Database.)
Chromosome 11, Monosomy 11q (Jacobsen Syndrome) is a rare genetic disorder affecting the long arm of chromosome 11. The disorder may be characterized by a narrow protruding forehead, eye problems, abnormally shaped nose and mouth and mental retardation. This syndrome is caused by a deletion on the long arm (q) of chromosome 11. The severity and type of abnormality depends upon the size and location of the missing chromosome piece. The cause of the chromosome break itself is unknown. (For more information on this disorder, choose "Chromosome 11, Monosomy 11q" as your search term in the Rare Disease Database.)
18p Syndrome is a deletion of the short arm (p) of chromosome 18. It is characterized by unusual facial features and mild to severe mental retardation. This syndrome may also include growth deficiency, diminished muscle tension and a smaller than normal sized brain. There may also be behavior problems and delayed speech. (For more information on this disorder, choose "18p" as your search term in the Rare Disease Database.)
Triploid syndrome can be diagnosed thorough cytogenetic (chromosome) analysis on a blood specimen. It can be diagnosed prenatally through cytogenetic analysis of cells obtained through amniocentesis or chorionic villus sampling. Abnormal levels of specific maternal blood proteins such as alpha-fetoprotein, human chorionic gonadotropin, estriol and pregnancy-assisted plasma protein-A have been associated with an increased risk for triploidy.
Treatment of triploid syndrome is symptomatic and supportive.
Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.
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Report last updated: 2008/05/21 00:00:00 GMT+0