What is it?
Situs inversus is a disease characterized by abnormal placement of the thoracic and / or abdominal organs. It is an inversion of these parts of the body compared to normal. This pathology can develop in isolation (without other underlying conditions) or may appear in addition to other deficiencies, abnormalities, pathologies. In addition, congenital heart defects are present in 5 to 10% of cases of the disease.
It is a complex and rare disease whose mode of transmission is genetic and hereditary.
The vital or long-term prognosis of patients with situs inversus depends directly on whether or not this pathology is associated with other abnormalities, particularly with cardiac deficiencies. Patients with the disease without underlying disease have an excellent prognosis. Conversely, when situs inversus is associated with other conditions or other pathologies, the prognosis also depends on these underlying causes and may therefore be less favorable.
The diagnosis of the disease can be made before the birth of the child during ultrasounds or MRI (Magnetic Resonance Imaging), which can provide additional information about fetal development, the progress of the disease and possibly the prognosis.
Postnatal exams provide a broader perspective and confirm prenatal diagnosis. These tests include genetic tests.
The knowledge of people with this pathology is important in the diagnosis of underlying medical problems associated or not as well as to prevent possible complications.
Symptoms of Situs inversus
In the context of the development of situs inversus without the presence of any other underlying anomaly, which could be the cause, the symptoms relate to a completely reversed image of the thoracic and abdominal disposition.
Many people with associated diseases, Kartagener syndrome or even primary ciliary dyskinesia, clinical manifestations result in that by symmetrically inverted placement of thoracic and abdominal organs added to the symptoms associated with the underlying conditions.
The severity of malformations varies from one patient to another. This can range from cardiac malformations to kidney, biliary, and other abnormalities.
Aplasia (presence of the spleen smaller than normal or totally absent) as well as polyspenia (presence of several small spleens with abnormality of lateralization), are also visible in the context of the disease.
The origins of the disease
Transmission of the disease is inherited genetically. Nevertheless, the transfer is complex. Several familial cases have been identified in which hereditary processes have been described.
The most common mode of transmission of the disease is autosomal recessive. That is, that the mutated gene of interest is located on a non-sexual chromosome and the presence of both copies of the mutated gene is indispensable in the development of the disease.
Other modes of hereditary transfer have also been demonstrated:
– the dominant autosomal transfer: the mutated gene is located on a non-sexual chromosome and the presence of only one of the two copies of the mutated gene is sufficient for the subject to develop the disease phenotype;
X-linked transfer: the mutated gene is located on an X sex chromosome.
The transmission of the disease is heterogeneously effective, which means that genetic factors or genes can interfere with the risk of mutations in different people.
In the context situs inversus is related to an underlying pathology, the transmission of the disease is usually the same as for the underlying pathology.
Risk factors for Situs inversus
The risk factors for developing the disease are genetic.
Indeed, different modes of transmission have been shown in the development of the disease.
In the context of an autosomal recessive transfer (for the majority of cases), a single copy of the mutated gene is not sufficient for the individual to develop the disease. Either it is essential for the subject to receive the mutated gene from both parents to develop the disease phenotype. In this case, if the associated risk factor is the presence of the disease in both parents.
Regarding the autosomal dominant transfer, this time, the presence of only one of the two copies of the mutated gene is sufficient for the individual to be sick. In this sense, the risk factor is that a subject has one of both parents with the disease.
Finally, X-linked transmission consists of the fact that the mutated gene is positioned on sex chromosome X. As girls possess XX sex genetic inheritance and XY boys, girls have an increased risk for the development of HIV. Disease.
Prevention and treatment of Situs inversus
The diagnosis of the disease involves physical examinations, followed by x-rays of the abdomen and thorax. The result is electrocardiography, which identifies the majority of cases of situs inversus. The difficulty in diagnosing this disease is that most people have no associated symptoms. In this sense, the diagnosis is made unexpectedly.
Genetic tests can, in turn, confirm or not the diagnosis. These genetic examinations are recorded in the Register of Genetic Tests (RTG).
The treatment also depends on the presence of underlying disease or not. Indeed, in the context of the development of situs inversus in isolation, no treatment is necessary. Moreover, when situs inversus is associated with other conditions, the treatment depends directly on the underlying disease.
Knowledge of the subject and its history is important in the medical diagnosis and in the prevention of possible complications. Proper medical identification can help ensure proper treatment in a medical emergency.