Our genetic code is so complex that almost any serious breakdown can cause a chain reaction and affect a person not from the best side. Scientists are constantly finding new diseases, but, in their own words, ninety percent of the genome remains unexplored.
Description
Larsen’s syndrome (ICD 10 - code M89) is a rare genetic disease that has a wide range of phenotypic manifestations. The most characteristic signs are dislocations and subluxations of large joints, the presence of malformations of the bones of the facial skull and problems with the functions of the limbs. Secondary manifestations include scoliosis, clubfoot, short stature, and difficulty breathing.
Larsen's syndrome is caused by point mutations that can occur both spontaneously and be inherited in an autosomal dominant manner. With changes in the FLNB gene, a whole group of diseases associated with skeletal system disorders is associated. Specific manifestations may be different even among relatives.
Causes
What must happen in the emerging organism for Larsen's syndrome to occur? The causes of this disease are still lurking in the scientific twilight. It is only known that autosomal dominant inheritance is characteristic of it. That is, just one copy of the changed gene will be enough to pass the pathology to your children, and maybe even grandchildren. A gene can be obtained from parents (from both or from one) or result from spontaneous mutation. The risk of inheriting this disease is 50/50, regardless of the gender of the child and the number of pregnancies.
The altered gene is located in the short arm of the third chromosome. If desired, researchers can accurately indicate the place where the hereditary information has undergone changes. Normally, this gene encodes a protein known in scientific circles as filamine B. It plays a significant role in the development of the cytoskeleton. Mutations lead to the fact that the protein ceases to fulfill the functions assigned to it, and the cells of the body suffer from this.
In people with this syndrome, mosaicism is possible. That is, the severity and number of manifestations of the disease directly depends on how many cells were affected. Some people may not even suspect that they have a defect in this gene.
Epidemiology
Larsen's syndrome develops with equal frequency in both men and women. According to very rough estimates, this disease occurs in one newborn out of a hundred thousand. This, fortunately, is very rare. Estimates are considered unreliable because there are certain difficulties in identifying this syndrome.
For the first time in the medical literature, the disease was described in the mid-twentieth century. Lauren Larsen et al. Found and documented six cases of the syndrome in children.
Symptoms
Larsen's syndrome, as mentioned above, can manifest itself in different ways even between close relatives. The most characteristic signs of the disease are changes in the bones of the face. These include: a wide low nose bridge and a wide forehead, a flat face, the presence of short lip or a hard palate. In addition, children have dislocations of large joints (femoral, knee, elbow) and shoulder subluxation.
The fingers of such people are short, wide, with weak loose joints. Additional bones may be present in the wrists, which merge with age and disrupt the biomechanics of movements. Some people have such a rare phenomenon as tracheomalacia (or softening of the cartilage of the trachea).
Diagnostics
The diagnosis of Larsen’s syndrome is made only after a complete examination of the patient, a thorough study of his medical history and the presence of characteristic radiological symptoms. In addition, a full-fledged radiographic examination can also reveal concomitant anomalies in the development of the skeleton, which are indirectly related to the disease.
Ultrasound diagnosis even in the prenatal period can reveal Larsen's syndrome. A photo of bone formations for a well-trained ultrasound specialist can be the starting point for the search for genetic abnormalities of the fetus. Since at first glance it cannot be said which disease led to the pathology of the facial skull and bones of the limbs, it is recommended that the future mother undergo amniocentesis and genetic testing to search for mutations in the third chromosome.
If the disease is confirmed, but the spouses have decided to continue the pregnancy, it is recommended that the expectant mother undergo a caesarean section so as not to damage the child’s bones during passage through the woman’s pelvis during natural childbirth.
Treatment
Therapeutic measures are aimed not at eliminating the disease, but at reducing clinical manifestations. This is done by pediatricians, orthopedists, specialists in maxillofacial surgery and genetics. After assessing the initial condition of the child and assessing all the risks, they can proceed with the correction of existing violations.
The most gentle option that treats Larsen's syndrome is massage. It is necessary to strengthen the muscles and ligaments that hold the joints, as well as to improve back support and straighten the spine. But before embarking on therapeutic methods, a number of operations will be required. They are necessary for the correction of gross skeletal deformities or deformities, stabilization of the vertebrae. With tracheomalacia, intubation is required, and then the placement of the respiratory tube (on an ongoing basis), which will maintain the patency of the upper respiratory tract.
The treatment of this disease is a long process that can last for years. As the child grows older, the load on the bones increases, and again he may need physical rehabilitation, physiotherapy exercises, and maybe even surgical intervention.