Heterotaxy is characterized by a side-to-side arrangement of body organs in the abdomen. Symptoms of this disorder vary quite a bit depending on the location of the organs, ranging from asymptomatic to severe life-threatening cardiac abnormalities.
What is heterotaxy?
Heterotaxy is not a disease in its own right, but represents a symptom complex of certain underlying genetic disorders. The word heterotaxy was derived from Greek and translated means “different arrangement.” Thus, this term refers to the deviant arrangement of body organs. This is the displacement of all or certain body organs from the right to the left half of the body or vice versa. This is referred to as a lateralization defect. A complete mirror-inverted distribution of the organs is also called situs inversus. However, this condition does not cause any physical problems and remains asymptomatic. However, severe health impairments are to be expected in the case of a partial displacement of organs. In these cases, in addition to severe heart defects, there are also abnormalities of the bile ducts or kidneys. In most cases, severe midline defects are also found. Thus, a therapy of heterotaxy depends on which organ defects are present. A complete exchange of organs in the context of a situs inversus does not require any treatment because there are no defects. Heterotaxy is a very rare disorder regardless of its degree of expression. Only one in 15,000 individuals is affected by this anomaly.
Causes
The common feature of all heterotaxias is the fact that these disorders are invariably genetic. In most cases, they represent a symptom or symptom complex of certain genetic disorders. Various genes may be responsible for the formation of heterotaxy, which have an importance for the left-right orientation of the body organs during embryonic development. These genes include ACVR2B, LEFTY A, CFC1 or ZIC3. Autosomal recessive, autosomal dominant, and x-linked inheritances are found. The most common is autosomal recessive inheritance. Rarer is already autosomal-dominant inheritance and very rarely x-linked transmission occurs. In autosomal recessive inheritance, both parents must be carriers of the defective gene. The offspring will only develop the disease if he or she receives the mutated genes of both parents. In high-risk families, this is the case in 25 percent of cases. In three percent of heterotaxies, only one gene is affected, and this is an autosomal dominant inheritance. Either the mutation occurs spontaneously or the defective gene is transmitted from an affected parent to the child in 50 percent of cases. Within affected families, the degree of expression of heterotaxy may be completely different despite the same genetic cause.
Symptoms, complaints, and signs
Heterotaxy, as mentioned above, is characterized by the displacement of body organs from left to right or vice versa. This may involve a complete exchange of the entire organs to the respective other side of the body. In this case, there are no symptoms because all organs retain their usual environment. However, if only individual organs change sides of the body, serious health problems often occur. In most cases, various heart defects are present, resulting from a condition called transposition of the great arteries or double outlet right ventricle. In transposition of the great arteries, large vessels of the heart are interchanged. It occurs during embryogenesis due to a disturbed rotation of the outflow tract of the heart. In a double outlet right ventricle, the pulmonary artery and aorta arise exclusively from the right ventricle of the heart. Sometimes the heart defect is also associated with the absence of the spleen (asplenia). In asplenia, the entire body possesses only the features of the right side of the body. Conversely, if the organism possesses features of the left half of the body only, there is always polysplenia. Polysplenia refers to the presence of many small spleens. In midline defects, which are often of x-chromosonal origin, arhine encephaly (absence of olfactory brain), clefts of the spine, cleft palate, malformations of the anus and coccyx, and urinary tract anomalies are frequently observed. A special disease is the so-called Kartagener syndrome.This genetic disease is characterized by the three symptom complexes situs inversus, bronchial outpouchings (bronchiectasis), and chronic sinusitis. Only the occurrence of situs inversus (complete interchange of organs) gives an indication of the genetic cause of the respiratory problems. In the absence of this symptom, the disease is PCD, the diagnosis of which is significantly more difficult.
Diagnosis and disease progression
The diagnosis of heterotaxy is made by imaging techniques. In the particular case of x-linked inheritance, the genetic defect in the ZIC3 gene can also be detected. Prenatal testing for heterotaxy in the case of familial clustering is also possible.
Complications
Heterotaxy results in an incorrect arrangement of organs in the patient’s body. However, the symptoms and complications depend on the exact arrangement of the internal organs, so no general prediction is possible in this case. However, there are usually serious complications that can be life-threatening for the affected person. As a rule, the affected person suffers from a heart defect, which in the worst case can lead to death. Furthermore, there may be discomfort and pain in the spleen. It is not uncommon for patients to suffer from the so-called cleft palate and respiratory complaints. This can result in gasping for breath, which in many cases leads to a panic attack. The quality of life of the affected person in extremely limited by the heterotaxy. Furthermore, the treatment is also not necessary if the exchange of the organs is complete. This does not result in a reduced life expectancy or further discomfort. If there are malformations of the organs, surgical procedures may need to be performed to resolve them.
When should you see a doctor?
Heterotaxy does not necessarily require a visit to the doctor. If there is freedom from symptoms and the patient does not experience any impairment in daily life, no doctor is needed. In some cases, heterotaxy need not result in any treatment for life. However, if the individual suffers from heart problems, there is cause for concern. If there is palpitations, elevated blood pressure or a feeling of pressure in the chest, a visit to the doctor is advised. In case of sleep disturbances, sweating, inner restlessness or disturbances of the blood circulation, further examinations should be initiated. If pain sets in, there is dizziness, a general feeling of illness or malaise, a doctor should be consulted. If the symptoms increase or spread, a doctor should always be consulted. If the general level of performance decreases, there are disturbances in concentration or attention deficits, a doctor is needed. Problems with breathing, the development of an anxiety disorder or panic attacks require a medical examination and therapy. Without their use, there will be a further deterioration of health and a significant impairment of the quality of life. In case of complaints of the spleen or repeated digestive problems, a doctor should be consulted. Heterotaxy can lead to a life-threatening condition. Therefore, a visit to the physician should be initiated immediately as soon as the affected person suffers from dysfunction or notices a sudden change in his or her health condition.
Treatment and therapy
Heterotaxy cannot be treated causally because it is a genetic disorder. Often, therapy is also not necessary, especially in the case of situs inversus, because no symptoms occur when the organs are completely exchanged. Only the organs are arranged laterally reversed. If the organs are affected by severe malformations, they must of course be subjected to specific therapy. However, the actual lateralization defect, i.e. the displacement of the organs, does not need to be treated.
Outlook and prognosis
The prognosis of heterotaxy varies widely and is established according to individual patient specifications. Basically, the order of organs in the body, which was created in the developmental process, cannot be completely changed in retrospect. The treatment is symptomatic. Accordingly, the further course and the prospect of alleviating the symptoms are assessed. There are a large number of patients who, despite heterotaxy, are free of impairments for life and do not experience any restrictions in the quality of their everyday life.Affected individuals receive a favorable prognosis, although regular check-ups are necessary to document general health and possible changes at an early stage. People who have only some anatomical displacements of organs or vessels usually have a worsening of the good prognosis. Transposition of major blood as well as heart vessels can be life-threatening for the patient and in severe cases lead to a shortening of the general life expectancy. If clefts occur, there is a need for surgical intervention and correction in most cases. A generally valid prognosis is not possible, as complications and sequelae may occur. If complaints of the respiratory tract are present, there is a risk of psychological illnesses in addition to the physical limitations. Anxiety, depression and behavioral problems can lead to a further deterioration of the prognosis. Some patients are dependent on assistance for the rest of their lives.
Prevention
Prevention of heterotaxy is not possible because of its genetic cause. However, prenatal testing for a lateralization disorder by sonography is always performed when heterotaxy occurs in the family. Human genetic counseling may also be sought in familial cases to assess the risk to offspring.
Follow-up
In heterotaxy, there are usually very few, if any, follow-up care measures available to the affected person. Affected individuals in this condition are primarily dependent on rapid and, above all, early diagnosis to prevent further complications and also further worsening of symptoms. Therefore, the main focus of heterotaxy is early detection with subsequent treatment. In the worst case, however, this disease can lead to death if the internal organs are affected by the disease. There is also no possibility of self-healing. Since it is a genetic disease, there is also no complete cure. If the affected person wishes to have children, genetic counseling may be useful to prevent further inheritance of the heterotaxy. In some cases, the malformations on the organs can be corrected. However, after such a surgical procedure, the affected person should always rest and take care of his body. They should refrain from exertion or stressful activities. The life expectancy of the affected person is significantly reduced by heterotaxy.
Here’s what you can do yourself
Because heterotaxy treats a genetic disorder, treatment is usually purely symptomatic. In some cases, no therapy is needed at all because there are no severe symptoms. Individuals suffering from heterotaxy should have regular medical checkups so that any health problems can be quickly identified and treated if necessary. If complications develop, a visit to the doctor is necessary. The most important self-help measure is to pay attention to the body’s signals and to document any abnormalities. If surgical intervention is necessary, the instructions of the doctor in charge must be followed. The patient must take care of himself before and after the operation and should follow a suitable diet free of stimulants. Depending on which organ needs to be surgically relocated, further measures may be taken. For example, in the case of surgery on the liver, care must be taken to spare the right upper abdomen. The surgical wound must be well cared for to prevent scarring and wound healing problems. Comprehensive aftercare is always indicated for surgery on the internal organs.
