Why Marfan syndrome?

summary

When it comes to genetic diseases, they feel that these patients are very unfortunate and pitiful, because all this is not caused by the day after tomorrow, but when they come to the world with this disease, which indicates that they can not have a normal life, and all this may be a mistake of the older generation or the older generation. But do you know the cause of Marfan syndrome?

Why Marfan syndrome?

Marfan's syndrome is an autosomal dominant genetic disease, and some of them are autosomal recessive. However, the more specific cause of Marfan's syndrome is still unclear. According to relevant experts, this disease is related to congenital abnormal protein metabolism. Dietz et al. (1991) mapped the gene to 15q15-q21.3 by linkage analysis. In many tissues of the human body, such as endocardium, heart valves, large blood vessels, bones and so on, there are accumulation of chondroitin sulfate A or C and other mucopolysaccharides, which affect the structure and function of elastic fibers and other connective tissue fibers, resulting in the corresponding organ dysplasia and abnormal function.

Through the family linkage gene mapping dominant inheritance, it can be proved from the increase of urine hydroxyproline excretion that the disease is elastic fiber defect, that is, abnormal collagen metabolism. Connective tissue fiber is a very important component in the organizational structure of the body. Therefore, when it is abnormal, it will affect the organs of the whole body (mesoderm tissue), especially the bone and cardiovascular system. In spider fingers and sunken chest or boat chest, it indicates that the longitudinal axis of tubular bone, fingers and ribs of limbs is overgrown, which may be due to the defect of periosteal fiber composition. There was acid mucopolysaccharide deposition in the middle of aorta and pulmonary artery.

Pathological changes of cardiovascular system: under the microscope, there were sparse and fragmented elastic tissue in the middle layer of aorta, with irregular thread like changes of smooth muscle, increased collagen content, and metachromatic substances scattered in the middle layer as cystic vacuoles. In patients with aortic dissection, cystic necrosis and moderate degeneration of elastic fibers were found, accompanied by disturbance of smooth muscle bundle. The histopathological changes of aortic valve were destruction and loss of normal structure, cystic degeneration and loss of tissue fibroblasts.

matters needing attention

Reed pyeritz of Johns Hopkins University Medical Center in Baltimore reported that myofibrillar protein deficiency can cause Marfan syndrome. Myofibrillar protein is one of the main components of the microfibrin system. The fibers of microfibrin form the scaffold of elastin, which is bound to the elastic tissue. This structural deletion leads to defects associated with Marfan syndrome, such as mitral valve prolapse and aortic aneurysm.