Edwards syndrome is a genetic disorder caused by the presence of an extra copy of chromosome 18 or by a portion of chromosome 18 translocated (attached) to another chromosome plus two copies of chromosome 18. It is the second most common genetic disorder caused by a trisomy, the most common being Down syndrome, or trisomy 21. Edwards syndrome was first identified in 1960 by a British geneticist, John H. Edwards (1928–2007), who analyzed blood samples taken from a severely malformed baby who died in a British children’s hospital.
Edwards syndrome is a condition in which babies who survive until birth have a low birth weight; small and abnormally shaped heads; small jaws and mouth; and clenched fists with overlapping fingers. They also suffer from mental retardation, heart defects, kidney disorders, and other organ abnormalities affecting most systems of the body. Most children with Edwards syndrome die within a few days of birth.
Edwards syndrome occurs once in every 6,000 to 8,000 live births in the United States. About 95 percent of children conceived with the syndrome, however, die before birth. Between 5 and 10 percent of children born with trisomy 18 live beyond twelve months. About 80 percent of children born with Edwards syndrome are female; it is thought that being male increases the risk of dying from the disorder before birth. The risk of having a child with the disorder increases with the mother’s age. Edwards syndrome is equally common in all races and ethnic groups.
Nursing Care Plan Signs and Symptoms
Almost all cases—92 percent—of Edwards syndrome involve genetic errors that occur during the formation of germ cells (eggs and sperm) or during cell division shortly after the egg is fertilized by the sperm. The most common form of Edwards syndrome occurs when an egg or sperm carrying two copies of chromosome 18 is involved in conception. The reason for the extra copy in the abnormal germ cell is a genetic error called nondisjunction. During the normal process of germ cell formation, the paired chromosomes in the cell divide so that each daughter cell has only one member of the pair. In nondisjunction, one daughter cell gets both members of the chromosome pair and the other cell has none. If a germ cell carrying two copies of chromosome 18 is fertilized by a normal germ cell from the other parent, the child will have three copies of chromosome 18. This genetic error is called a full trisomy 18.
A few cases (about 2 percent) of Edwards syndrome develop when a part of chromosome 18 becomes attached to another chromosome either before or at the moment of conception. This type of genetic error is called a translocation. The child will be born with two copies of chromosome 18 plus some extra genetic material from chromosome 18 attached to another chromosome. A child with this type of genetic error is said to have partial trisomy 18. About 5 percent of cases of Edwards syndrome occur in children who have some body cells with the extra copy of chromosome 18 and some body cells without the extra copy. This condition is called mosaic trisomy 18. It is thought to result from random errors in cell division during the early stages of fetal development. Children with mosaic trisomy 18 are less severely affected than those with full trisomy 18 and have a longer survival period.
The symptoms of Edwards syndrome include a high mortality rate even before birth. Most embryos with full trisomy 18 die during pregnancy or are expelled from the mother’s womb in what is called a spontaneous abortion or miscarriage. Those who survive until birth usually live only a few days; most die from breathing problems, heart or kidney defects, generalized infection, or feeding difficulties. Although some children with mosaic trisomy 18 do not have all the physical features that characterize the syndrome, the following are considered typical:
• Mental retardation and delayed movement (100 percent of infants)
• Poor muscle tone, seizures, and breathing difficulties
• Abnormally small head, abnormally small eyes, flattened nose, small jaw, pointed ears, cleft lip, and cleft palate
• Severely retarded growth with clenched hands, missing bone in forearm, rocker-bottom feet
• Heart abnormalities (90 percent of infants), underdeveloped lungs, incomplete esophagus, double spleens, missing appendix, and missing gallbladder
• Underdeveloped sex organs in both boys and girls
• Underdeveloped thyroid and thymus glands
Nursing Care Plan Diagnosis
Diagnosis of Edwards syndrome is usually made on the basis of the child’s appearance at birth. It can be diagnosed before birth on the basis of ultrasound studies during the first three months of pregnancy; a sample of the mother’s blood plasma; or by genetic analysis of cells taken from the baby’s blood or the amniotic fluid that surrounds the baby inside the womb.
In some cases the diagnosis is suspected before birth on the basis of certain characteristics of the pregnancy. These include a smaller than average placenta (the organ that attaches the baby to the wall of the mother’s uterus), a low level of fetal activity, irregular heartbeat, and slowed fetal growth.
Nursing Care Plan Treatment
There is no treatment for Edwards syndrome itself. Infants who survive the first two days often require intensive treatment for infections, breathing difficulties, and problems with feeding. Surgery to correct heart defects is rarely performed because of the baby’s short life expectancy.
Nursing Care Plan Prognosis
The prognosis of Edwards syndrome is extremely poor. Newborns have a 40 percent chance of living a full month; infants have a 5 percent chance of surviving a full year; children have a 1 percent chance of surviving to age ten years. The very small number of children with Edwards syndrome who live as long as ten years suffers from severe mental retardation, digestive problems, and difficulty in walking.
Nursing Care Plan Prevention
Since Edwards syndrome is thought to be caused by a spontaneous genetic mutation rather than an inherited genetic defect, there is no way to prevent it. Pregnant women over thirty-five should have tests during the first trimester (three-month period) of pregnancy to screen for the syndrome. These tests may involve ultrasound studies, which can detect abnormalities in the baby’s heart or facial development, followed by a photographic analysis of cells taken from the fluid that surrounds the baby in the womb. This analysis, or karyotype, is needed to distinguish
Edwards syndrome from other genetic disorders that can cause heart defects and facial abnormalities. Doctors recommend that the parents of a child with Edwards syndrome should consult a genetic counselor for advice about future pregnancies.
The Future
It is possible that the increasing numbers of women having children in their thirties or forties will lead to an increase in the number of children born with Edwards syndrome. Many women whose fetuses are diagnosed with the syndrome choose to end their pregnancies before childbirth. A newer option is the perinatal hospice (see sidebar), a special type of hospital program where parents who know that their baby has a fatal condition can choose to have the baby and remain with it during the baby’s few days of life.
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