Edwards Syndrome Kylie Allen Medical Genetics R. Ostrowski, PhD. and L. McNally, M.S. July 6, 2002 Abstract Edwards syndrome is a common chromosomal abnormality caused by nondisjunction. Through karyotyping and various prenatal techniques, Edwards syndrome can be diagnosed before the birth of a child. Many children with this disorder do not live to their first birthday; however, therapy and other remedies can prolong the life of an Edwards syndrome child. The distinct deformities of this abnormality include low set ears, overlapping fingers and toes, and a small head circumference, which help distinguish it from other trisomy disorders (Disorder Zone Archives, 2001). There is no cure for Edwards syndrome, but scientists are trying to advance their knowledge of this sporadic disease. Introduction Edwards syndrome was first discovered in 1960 when an extra chromosome 18 was found in newborn babies. Edwards, et al. (along with Patau, et al., and Smith, et al.) determined that this was a chromosomal abnormality that caused distinct malformations in babies with this disorder (Pediatric Database, 1993). Edwards syndrome occurs in 1/8000 births; however, most are spontaneously aborted in the embryonic stage. Thirty percent of the infants born with Edwards syndrome die within the first month, 50% die within two months, and 10% survive a year. It is the second most common autosomal aberration and second most common multiple malformation syndrome (Pediatric Database, 1993). Phenotypic Milestones and Diagnostic Techniques Edwards syndrome is easily recognized by distinct dysmorphic features found in the newborn. The typical facial phenotype of an Edwards syndrome child includes a small head circumference (microcephaly), low-set ears, cleft lip/cleft palate, widely-spaced eyes, dropping of the upper eyelids, an abnormally small jaw, an upturned nose, and a prominent back portion of the head (see Figure 1). On the extremities of the body there are rocker bottom feet, underdeveloped or absent thumbs, overlapped fingers (see Figure 2), underdeveloped nails, and webbing of the second and third toes. Overall, these babies are severely retarded, hypertonic (rigid), and have growth deficiencies, breathing difficulties, feeding difficulties, and developmental delays. Although Edwards syndrome babies are mostly girls, the males that are born with this disorder have undescended testicles (Disorder Zone Archives, 2001). Edwards syndrome is found by a technique called karyotyping. Karyotyping allows a physician to view a layout of a patients’ chromosomes. In doing this, a clear picture of three chromosomes (trisomy) in 18 is seen in Edwards babies (see Figure 3). Intrauterine studies can also be used to determine if the baby has this abnormality. If the mother has an overly large uterus during pregnancy, and if there is feeble fetal activity and excessive fluid in the fetal sac, the child may be at risk of Edwards syndrome (Disorder Zone Archives, 2001). Not all Edwards syndrome cases are detected before birth. The first symptoms of an Edwards baby are a low birth weight, a weak cry, and the baby is either frail or does not survive (see Figure 4; Disorder Zone Archives, 2001). Discussion Although there have been numerous studies on Edwards syndrome, geneticists have not been able to find a cure for this deadly disorder. There are, however, treatments for the individual symptoms of Edwards syndrome. For example, many babies can undergo therapy for their breathing, feeding, and muscle abnormalities. Also, babies that suffer from low weight gain can be taken to a nutritionist for a special diet. Irritability, hearing and vision impairments, and constipation are just a few more symptoms that can be handled with a variety of treatments. The only problem is that there is not a remedy for all of the difficulties these babies have to live through. The prognosis of an Edwards syndrome child is not very encouraging. As already mentioned, most die within their first year of life. With intense therapy, there have only been a few miraculous cases of children living to their tenth birthday (Disorder Zone Archives, 2001). A continuous study is being done to find a cure for Edwards syndrome. Scientists have posed questions for the further development of research techniques that may be possible in the near future. These questions include theories on the molecular structure of Edwards syndrome and the natural history of the affected person. Edwards syndrome is an abnormality that is one of the most common malformation disorders yet seems to still boggle the minds of geneticists. There is no hereditary pattern that it follows and no other way of tracking who is going to contract this deadly disease. Because of its sporadic nature, Edwards syndrome has been very difficult to diagnose and impossible to cure. As technology and knowledge increases, we can only hope that sometime in the near future there will be some sort of permanent treatment to help those affected with Edwards syndrome. References Disorder Zone Archives. <http://www.specialchild.com/archives/dz-038.html>. 2001. (Date accessed July 6, 2002). Klatt, Dr. Edward C., MD. <http://mirrors.cmb.ro/medgen.genetics.utah.edu/photographs.htm>. (Date accessed July 7, 2002). Pediatric Database. <http://www.icondata.com/health/pedbase/files/TRISOMY2.HTM>. November 12, 1993. (Date accessed July 6, 2002). Figure 1. This shows the facial phenotype of a typical Edwards syndrome baby with cleft lip/cleft palate (Klatt, Dr. Edward C., MD). Figure 2. This is an example of the overlapping of the fingers in an Edwards baby (Klatt, Dr. Edward C., MD). Figure 3. This Karyotyping of Edwards syndrome points out the trisomy of chromosome 18 (Klatt, Dr. Edward C., MD). Figure 4. This shows an Edwards syndrome newborn fighting to survive (Klatt, Dr. Edward C., MD).
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