Trisomy 22 is an inherited disorder in which chromosome 22 is present three times. The disease causes both cognitive and physical disabilities. Affected individuals can suffer from the limitations with varying degrees of severity.
What is trisomy 22?
Trisomy 22 is a genetic condition that leads to mental and physical impairments. The disability can vary in severity. Trisomy occurs because of an error in cell division. Normally, human cells have a double (diploid) set of chromosomes, in which each chromosome is present twice. In the case of trisomy, however, the affected chromosome appears three times in the genome. Medicine distinguishes between different subtypes of trisomy 22:
- In free trisomy 22, all body cells have three 22nd chromosomes, which are independent of each other and clearly separated.
- In the case of translocation trisomy 22, the extra chromosome translocates and joins with another. Therefore, at first glance, the chromosome set appears to have the correct number of chromosomes.
- In partial trisomy 22, only one section of a chromosome is duplicated. Accordingly, this part (Latin “pars”) is present in triplicate. Visually, partial trisomy is characterized by the fact that one of the affected chromosomes is longer: it carries the additional part.
- In contrast, people with a mosaic trisomy have both trisomic cells and disomic cells; the trisomy is confined to only one cell line. Most affected individuals have such a mosaic trisomy, as the probability of survival in this type is significantly higher than in other forms.
Causes
The cause of trisomy 22 is an error in cell division. Normally, when a cell divides, one chromosome from each species migrates into one of the two halves of the cell. Immediately after division, the new cells therefore have a single (haploid) set of chromosomes. Only then does the cell copy the genetic information so that there are again two chromosomes from each species. However, errors can occur in this process. If the chromosomes do not divide properly between the two halves of the cell, one of them has one chromosome too many. Nevertheless, the cell makes a copy of one of the chromosomes; therefore, in the finished cell there are three chromosomes 22 instead of only two. Such errors in cell division can occur in both males and females. Therefore, the cause of trisomy 22 in the child can be equally in the father or in the mother.
Symptoms, complaints and signs
The symptoms of trisomy 22 include both mental and physical impairments. Mental symptoms primarily include cognitive impairment. Affected individuals may have a lower intelligence quotient (IQ), for example. Cognitive impairments therefore show up in different areas of thinking. However, in the case of trisomy 22, especially the mosaic type, the extent to which the brain cells are affected by the trisomy is highly dependent. In approximately 50 percent of affected children, a heart defect manifests itself. This is a malformation of the organ: the anatomical shape of the heart or its blood vessels has special features. They cause the heart not to work properly or to tire prematurely. Doctors therefore recommend regular monitoring even in the case of heart defects that do not pose an acute danger. Heart defects in trisomy 22 are only one of the possible organ damages. In mosaic trisomy 22, it depends on which cells of the organism are affected by the trisomy – the type and extent of the organic malformations also depend on this.
Diagnosis and course of the disease
External physical features may provide the first signs of trisomy 22. Affected children often have a strikingly broad skull and high forehead. The face is often flat with widely spaced eyes, low-set ears, and beak-shaped nose. The lower jaw typically protrudes. Genetic testing can detect trisomy 22 beyond a doubt.
Complications
Trisomy 22 results in many different limitations and symptoms. Usually, affected individuals suffer from a number of different cognitive and motor disorders in the process, which cannot be treated directly.Mental retardation also occurs, so that patients are dependent on the help of other people in their lives. However, trisomy 22 can also lead to a heart defect, so that those affected can die of sudden cardiac death. The heart itself cannot work properly due to the malformation, so patients quickly appear tired and exhausted. For this reason, they are dependent on regular examinations to avoid further complications. However, other organs may also be damaged by trisomy 22. The disease can also lead to aesthetic complaints. Patients often do not feel beautiful and thus suffer from reduced self-confidence or, in childhood, from bullying or teasing. Since a causal therapy of trisomy 22 is not possible, only the individual complaints and symptoms of the disease can be alleviated. No complications occur in the process. The relatives and parents are also often affected by the psychological discomfort of the disease and thus also need treatment.
When should one go to the doctor?
The affected person is dependent on medical examination and treatment for trisomy 22 so that further complications can be prevented. In the worst case, if left untreated, this condition will result in the death of the affected person, so early diagnosis with subsequent treatment will always have a very positive effect on the further course of trisomy 22. Since it is also a genetic disease, genetic counseling should also be performed in the event that a child is desired. A doctor should be contacted if the affected person suffers from significantly impaired intelligence. Furthermore, heart problems or malformations all over the body may also indicate this disease and should be examined by a doctor. Rapid fatigue or permanent exhaustion may also indicate this disease. Usually, trisomy 22 is detected by a pediatrician or by a general practitioner. Further treatment depends on the exact symptoms and is carried out by a specialist. In some cases, the life expectancy of the affected person is also reduced by this disease. Not infrequently, parents and relatives are also dependent on psychological treatment.
Treatment and therapy
Trisomy 22, like all trisomies, is not curable. Affected cells have three 22nd chromosomes from birth and cannot lose the extra chromosome. Treatment is therefore mainly directed against the damage that occurs as a result of the mutation. In individual cases, treatment can therefore vary greatly. Since heart defects are particularly common, medical therapy often focuses on the vital organ. Physical and occupational therapy usually support the treatment of the physical disabilities. If children with trisomy 22 show severe behavioral problems, psychotherapeutic approaches may also be considered. They may also be useful if those affected suffer severely from social or emotional consequences of the disability.
Prevention
To prevent trisomy 22 and similar conditions, proactive family planning is beneficial. The likelihood of such mutations increases the older the child’s mother is. Medical experts consider an age of the mother of less than 35 years to be relatively uncritical. In this age range, the risk of trisomy is significantly lower. Nevertheless, these are only probabilities: Even a young maternal age is no guarantee to completely rule out trisomy or other genetic defects. For mothers over 35, prenatal diagnosis may be advisable, as children with trisomy 22 are often not born alive. Older age of the father also increases the risk of trisomy in the child.
Follow-up
Because the clinical picture of trisomy 22 varies widely, individualized follow-up care is also required. Follow-up involves monitoring the specifics associated with the chromosomal disorder and, if necessary, initiating treatment of problems if this can reduce them. Patients who are cognitively impaired in most cases benefit from lifelong support measures initiated at an early stage. Limitations of the musculoskeletal system and motor skills can be improved by physical or occupational therapy during follow-up.The heart defects that occur in approximately every second affected person require close monitoring even after the actual treatment. In this way, deteriorations can be detected at an early stage, and the treating cardiologist can take appropriate measures if necessary. Follow-up care also includes the care of relatives. The parents of children with trisomy 22 should be supported so that they can manage the care of the child in the best possible way. If necessary, psychological help may be useful. After a woman has given birth to a child with trisomy 22, human genetics can be used to determine whether there is an increased risk of recurrence. During a subsequent pregnancy, prenatal diagnostics can provide information on whether the child is affected again. However, the risks of invasive diagnostic procedures should not be ignored.
What you can do yourself
Trisomy 22 from the group of hereditary diseases is not curable, but there are self-help and support options with which the quality of life can be sustainably increased. Due to the heart defect, it is important to pay attention to a healthy diet. In particular, avoiding overeating and foods containing cholesterol has a positive effect. Excessive sports should not be practiced, but casual walking in the fresh air is recommended. A regular check-up of the heart must be carried out by a specialist several times a year. Occupational and physiotherapy can help to treat motor impairments, in particular to maintain existing abilities and skills. Specially trained motologists help to experience the body’s own limits and to establish a positive relationship with it. Psychotherapeutic treatment is indicated, for guidance and support in everyday life. Emotional and social stress factors are identified and resolved in a protected environment. Conversational and behavioral psychotherapy are particularly suitable for this purpose. Systemic psychotherapy has a positive effect on problems that affect the social and family environment. A broad social environment with diverse points of contact has a positive effect. Self-help groups provide a place where experiences are exchanged and further information and help is offered.
