Edwards syndrome is a genetic disorder, in which a person has a third copy of material from chromosome 18, instead of the usual two copies. It is three times more common in girls than boys. The syndrome is caused by the presence of extra material from chromosome 18, which interferes with the normal development.
It is often referred to by another name, i.e. trisomy 18.
Edwards syndrome is caused by a meiotic nondisjunction event. With nondisjunction, a gamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 18. The gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo has 47 chromosomes, with three copies of chromosome 18.
In most cases, all the cells in an affected body has extra chromosome 18. In about 5% of the affected persons, only some cells in their body are affected by extra chromosome, which is called as mosaic trisomy 18. The severity depends on the number of cells affected by extra chromosome 18, in a body.
In rare cases it is noticed that instead of extra chromosome, a portion of its long arm is attached to another chromosome, at the time of the egg or sperm formation, which is known as translocation. In such cases, a person has two copies of chromosome18, plus the extra material from chromosome 18. The extra genetic material is responsible for abnormalities.
Symptoms of Edwards syndrome
The symptoms of Edwards syndrome may differ from one affected individual to another. Some of the signs and symptoms of Edwards syndrome are as follows:
- Underdeveloped fingernails
- Undescended testicles
- Unusual shape of the chest
- Feet with a rounded bottom
- Low birth weight
- Clenched hands
- Under developed or missing thumbs
- Crossed legs
- Webbing of second and third toe
- Upturned nose
- Widely placed small eyes with narrow eyelid folds
- Drooping of upper eye lids
- Low-set ears
- Mental deficiency
- Small head
- Small jaw
- Cleft in iris
- Umbilical hernia
- Diastasis recti
- Structural malfunctions of heart, brain, genitals, kidneys, and the digestive tract, may cause problems in breathing, feeding etc.
- Delay in growth and development
- Infections in lungs and in urinary system
Causes of Edwards syndrome
- Edwards syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on the 18th chromosome, either in whole or in part. The additional chromosome usually occurs before conception. The effects of the extra copy vary greatly, depending on the extent of the extra copy, genetic history, and chance.
- A healthy egg or sperm cell contains individual chromosomes; each of which contributes to the 23 pairs of chromosomes needed to form a normal cell with 46 chromosomes. Edwards syndrome results in an extra chromosome, making the number 24 rather than 23. Fertilization of eggs or insemination by sperm that contain an extra chromosome results in trisomy, or three copies of a chromosome rather than two.
- A small percentage of Edwards syndrome cases occur when only some of the body’s cells have an extra copy of chromosome 18. Such cases are called as mosaic Edwards’ syndrome. Very rarely, a piece of chromosome 18 becomes attached to another chromosome (translocated) before or after conception. Affected individuals have two copies of chromosome 18 plus extra material from chromosome 18, attached to another chromosome. With a translocation, a person has a partial trisomy for chromosome 18, and the abnormalities are often less severe than for the typical Edwards syndrome.
- Edwards syndrome is not an inherited disorder, it happens at random during the egg or sperm formation, which is known as nondisjuction, and is responsible for the extra chromosome. The reason for causing abnormalities by the extra material is unknown. However the experts believe that it interferes in the interaction of various genes and cause impairments.
- One child in 6000 births is affected by Edwards syndrome. 80% of children with this syndrome belonged to female segment. Majority of the syndrome affected children die before birth. People with all types of cultural background get affected by this syndrome. The risk of Edwards syndrome increases with the increase in the maternal age.
Edwards syndrome treatment
There is no known cure for Edwards syndrome. The treatment for the disorder is given as per the presence and severity of the symptoms. Some of the treatments include the following:
- Providing good, nutritious food
- Treating infections which occur frequently
- Aiding and engaging in activities for the better functioning of the heart and the digestive track
- If necessary, children with feeding difficulties may be provided with alternatives such as feeding via a nasogastric tube
- Physiotherapy and occupational therapy for children with limb disorders
- Providing emotional support for parents, as very few children with this syndrome survive beyond one year
Edwards Syndrome life expectancy
Nearly half of the children affected by Edwards’ syndrome do not survive beyond a week’s period. Very few survive up to the teenage with all developmental disorders. The average life span is 5 to 15 days. 8 percent of infants are able to live more than 1 year while 1 percent of children live up to the age of 10 years.
Edwards Syndrome pictures