Trisomy 18, or Edwards syndrome, is a condition caused by a genetic defect in chromosome No.18. Instead of normally being laid out as a pair, the chromosome occurs in triplicate in the condition. No treatment is yet available, and children usually die only a few days or weeks after birth.
What is trisomy 18?
Trisomy 18 is a genetic disorder. Normally, each person has a chromosome set of 23 pairs, or 46 individual chromosomes. At fertilization, the pairs of mother and father divide and the respective chromosomes rejoin to form new pairs. In trisomy 18, one pair of the 18th chromosome does not divide. This results in a triple chromosome in each cell when the new pair is joined (Free Trisomy 18). Since the blueprint for the human body with all its functions is located on the chromosomes, an incorrect arrangement causes corresponding disorders and malformations. In addition to free trisomy 18, there are other rare variants of the disease, such as mosaic trisomy 18, in which the triple set of chromosomes is present only in some cells, and translocation trisomy 18, in which only fragments of the 18th chromosome are triple. The condition trisomy 18 is also called Edwards syndrome, after its discoverer, human geneticist John Hilton Edwards.
Causes
The cause of the occurrence of trisomy 18 is not known. In free and mosaic trisomy 18, it happens purely by chance that one of the chromosome pairs No. 18 does not divide and is then present in triplicate in the cells of the child. The defect occurs without any apparent cause during cell division. However, it is known that as the mother ages, the likelihood of free trisomy 18 increases. In translocation trisomy 18, the father or mother is the carrier of the defect. This means that the condition can occur more often within the family and that the predisposition to trisomy 18 can be passed on to offspring.
Symptoms, symptoms, and signs
Trisomy 18 is characterized by typical symptoms that can quickly give an indication of the hereditary condition. Many physical malformations and mental impairments are particularly pronounced. The life expectancy of children with Edward’s syndrome is greatly reduced. Only about five to ten percent of those affected live beyond the age of one year. However, some children have already reached and exceeded the age of ten. They are born with a low birth weight because physical development in the womb is already delayed. The most striking features are low-set ears, fused auricles, protruding back of the head, small chin and possibly a cleft lip and palate. Furthermore, bone malformations of the ribs, vertebrae and pelvis occur. Many internal organs such as the heart, gastrointestinal tract or kidneys are also often malformed. The same applies to the brain. Patients also frequently suffer from respiratory problems. The bulging forehead and short eyelid fissures are also typical. Deformed feet (club feet) are often observed. Eye malformations and malformations of the fingers also occur. For example, the index finger is often folded over the third and fourth fingers. Due to the brain malformation, the mental and motor development of the affected children is severely retarded. The children can sit and crawl only much later. As a rule, learning to speak is not possible for them.
Diagnosis and course
The course of trisomy 18 is very striking. Already in the womb, the children are behind in their development. They weigh too little and have too small a head. The shape of the skull also deviates from the norm; the back of the head is very protruding. In addition, there are various abnormalities in the face, such as a too small chin, malformations of the eyes or a cleft lip and palate. The organs are not normally formed. The heart, stomach, intestines and also the kidneys often have defects and do not function properly. The skeleton is also poorly formed, often vertebrae or ribs are missing or deformed. Trisomy 18 can be diagnosed in the womb. During regular check-ups during pregnancy, the doctor usually notices growth delays and a lack of movement. If trisomy 18 is suspected, a genetic test is usually performed.In an amniocentesis, amniotic fluid is removed through the abdominal wall using a cannula and examined. Since the amniotic fluid contains cells of the embryo, it can be used to determine the chromosomes. This examination can be used both to diagnose trisomy 18 with certainty and to determine which form of the condition is present.
Complications
Trisomy 18 leads to various disorders and symptoms. As a rule, physical and mental disabilities occur, which considerably complicate the daily life of the affected person. The patients thereby suffer from severe developmental disorders and furthermore also from growth disorders. In many cases, they are therefore dependent on the help of other people in their daily lives. The malformations of the eyes caused by trisomy 18 can have a negative effect on the vision of the affected person. Furthermore, a cleft palate develops, which can lead to discomfort when taking food and liquids. Many affected individuals also suffer from a heart defect. If left untreated, this can lead to the death of the patient. The clubfoot can cause restricted movement. Many children also suffer from bullying and teasing due to trisomy 18 and often develop physical discomfort or depression as a result. Parents may also be affected by the psychological discomfort. Since a direct and causal treatment of trisomy 18 is not possible, no complications occur. As a rule, the affected persons die relatively early, so that the life expectancy of the patients is extremely limited.
When should you see a doctor?
The affected person must see a doctor in Edwards syndrome in any case. In this case, self-healing cannot occur, so medical treatment must be carried out in any case. The earlier the disease is detected, the better the further course is usually. Since it is a hereditary disease, a complete cure is not possible. If a child is desired, genetic counseling should also be performed to prevent the recurrence of Edwards syndrome. A doctor should be contacted if the affected person suffers from various deformities and malformations. They occur mainly in the face and can significantly complicate the daily life and the life of the affected person. In many cases, decreased intelligence may also indicate Edwards syndrome and should be evaluated by a physician. It is also not uncommon for parents and family members to require psychological treatment to prevent depression or other psychological upsets.
Treatment and therapy
There is no therapy for trisomy 18. The damage and malformations are so severe that no treatments are available. For mosaic trisomy 18, which is somewhat milder, it is sometimes possible to keep the children alive a little longer with surgery and treatment. There are even a few individual cases in which children with mosaic trisomy 18 have even reached adolescence. Free trisomy 18, on the other hand, is always fatal. The children usually survive only a few days or weeks. If the diagnosis of trisomy 18 is certain, affected parents are often advised to abort the pregnancy.
Prevention
Trisomy 18 cannot be prevented because the condition is caused by a genetic defect.
Follow-up care
Follow-up care for trisomy 18 is primarily palliative in nature. The goal is to help children live pain-free or pain-free lives during their usually short lifespan. Patients with Edwards syndrome must be examined regularly to assess their physical condition. Known physiological defects are regularly checked for changes by the attending physician. In this way, measures can be initiated if necessary should the condition worsen. Since almost all children with trisomy 18 die during the first months or years of life, psychological support for the parents is also part of good follow-up care. Professional support for the family and good palliative care for the children make it easier for everyone involved to deal with the stressful situation. Support for affected families is usually provided not only by physicians, but also by other professional groups such as psychologists, chaplains and others. It should continue after the death of the child for as long as those affected wish.No special precautions need to be taken for a repeat pregnancy, as the risk of recurrence is low. Nevertheless, many parents consult a human geneticist and can thereby reduce doubts and fears.
What you can do yourself
Because trisomy 18 is usually a very serious condition, a large proportion of children born die in the first few weeks of life. Even with treatment, only about 15 percent of girls reach ten years of age, and adulthood is extremely rare. The main focus is therefore on alleviating the symptoms and accompanying the child through the family. Self-help groups and topic-related forums (e.g. Leona e.V.) enable them to exchange experiences with other affected persons. The concrete possibilities for coping with everyday life depend on the type and severity of the disability. In severe cases, i.e. with an unfavorable prognosis, there are specialized palliative care nurses for children who provide support to the parents. While the treatment of primary symptoms (e.g., organ damage) is left to medical professionals, the resulting symptoms (e.g., difficulty in feeding) tend to fall within the scope of nursing care. Some institutions (e.g. “Berliner Sternschnuppen”) offer free nursing courses for parents of disabled children. Specialized outpatient care services can support and advise parents in home care. In addition to the offers mentioned, early intervention offers (physiotherapy, occupational therapy) should be taken advantage of if possible. They can help relieve cramps and achieve motor or cognitive progress.
