Triple X Syndrome
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What is triple X syndrome?Triple X syndrome, also called trisomy X or 47,XXX, is characterized by the presence of one extra X chromosome in each of a female's cells. Most often, this chromosomal change causes no unusual physical features or medical problems. Females with triple X syndrome are sometimes taller than average and have an increased risk of learning disabilities and delayed speech and language skills. Developmental delays and behavioral problems are also possible, but these characteristics vary widely among affected girls and women. Most females with triple X syndrome have normal sexual development and are able to conceive children. How common is triple X syndrome?This condition occurs in about 1 in 1,000 newborn girls. Five to 10 girls with triple X syndrome are born in the United States each day. What are the genetic changes related to triple X syndrome?Triple X syndrome is a chromosomal condition related to the X chromosome. People normally have 46 chromosomes in each cell. Two of the 46 chromosomes are sex chromosomes, called X and Y. Females have two X chromosomes (46,XX), and males have one X chromosome and one Y chromosome (46,XY). Triple X syndrome results from an extra copy of the X chromosome in each of a female's cells. As a result of the extra X chromosome, each cell has a total of 47 chromosomes (47,XXX) instead of 46. It remains uncertain why an extra copy of the X chromosome is associated with tall stature and learning problems in some girls and women. Some females with triple X syndrome have an extra X chromosome in only some of their cells. These cases are called 46,XX/47,XXX mosaics. Can triple X syndrome be inherited?Trisomy X usually is not inherited, but occurs as a random event during the formation of reproductive cells (eggs and sperm). An error in cell division called nondisjunction can result in reproductive cells with an abnormal number of chromosomes. For example, an egg or sperm cell may gain an extra copy of the X chromosome as a result of nondisjunction. If one of these atypical reproductive cells contributes to the genetic makeup of a female child, the child will have an extra X chromosome in each of the body's cells. In some cases, trisomy X results from nondisjunction during cell division in early embryonic development. These cases are usually 46,XX/47,XXX mosaics.
Source: National Institutes of Health
Findings from University of Leipzig provide new insights into syndrome
2007 SEP 24 -- Scientists discuss in "Duodenal atresia in an infant with triple-X syndrome: a new associated malformation in 47,XXX" new findings in syndrome. According to a study from Leipzig, Germany, "An association between the triple-X syndrome (47,XXX) and gastrointestinal malformations is extremely rare. Most 47,XXX patients present with a normal phenotype, but genitourinary malformations have been described." "We report a case of a child with 47,XXX and duodenal atresia. Antenatal ultrasound scan showed a dilated fetal stomach and upper part of the duodenum (double bubble phenomenon) at 31 weeks of gestation in a 31-year-old woman with polyhydramnion. The amniotic fluid karyotype showed 47,XXX. After a scheduled delivery, duodenal atresia was confirmed and treated with duodeno-duodenostomy," wrote U. Rolle and colleagues, University of Leipzig. The researchers concluded: "The possible association of gastrointestinal and genitourinary tract anomalies requires a detailed postnatal clinical investigation and ultrasonographic examination of the abdomen, retroperitoneum, and pelvis on all triple-X syndrome patients." Rolle and colleagues published the results of their research in Birth Defects Research Part a (Duodenal atresia in an infant with triple-X syndrome: a new associated malformation in 47,XXX. Birth Defects Research Part a, 2007;79(8):612-3). For additional information, contact U. Rolle, University of Leipzig, Dept. of Paediatric Surgery, Leipzig, Germany. The publisher of the journal Birth Defects Research Part a can be contacted at: Wiley-Liss, Division John Wiley & Sons Inc., 111 River St., Hoboken, NJ 07030, USA. Keywords: Germany, Leipzig, Gastroenterology, Syndrome, Triple X Syndrome. This article was prepared by Gastroenterology Week editors from staff and other reports. Copyright 2007, Gastroenterology Week via NewsRx.com.
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