Causes of undifferentiated connective tissue dysplasia
Last reviewed: 23.04.2024
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Undifferentiated connective tissue dysplasia is a multifactorial disease, often associated with an anomaly of collagen or other connective tissue proteins (elastin, fibrillin, collagenases). In the synthesis of 27 types of collagen, 42 genes are involved, more than 1,300 mutations are described in 23 of them. The variety of mutations and their phenotypic manifestations complicates the diagnosis. Given the wide representation of connective tissue in the body, this group of disorders often complicates the course of diseases of organs and systems. Skin, musculoskeletal system, heart valves, all layers of the esophagus wall (except epithelium) have a mesenchymal origin. Pre-school and junior school age is allocated as critical periods for the formation of connective tissue failure. The main target organs are skin, musculoskeletal system, cardiovascular system, nervous system. The degree of changes in internal organs is closely related to the number of external manifestations of NDT.
Undifferentiated connective tissue dysplasia is a genetically heterogeneous group that serves as the basis for the formation of various chronic diseases. There are acquired forms that arise as a result of the influence of various unfavorable factors on the fetus during its intrauterine development. The data of the pedigrees testify to the accumulation in the families of sick children of such pathology as osteochondrosis, osteoarthritis, varicose veins, hemorrhoids, etc. A number of phenotypic signs of DST and microanomalies are distinguished, which can be divided into external ones, revealed during physical examination, and internal, that is, CNS damage and organ pathology. Prognostic factors of the genealogical anamnesis for the formation of DST - the presence of signs in relatives of I and II degree and sibs of deformity of the chest, mitral valve prolapse, hypermobility of the joints, hyperextension of the skin, spine pathology, myopia. Antenatal criteria for unfavorable prognosis: age of mother over 30, unfavorable course of pregnancy, acute illness of mother in I trimester.
Undifferentiated connective tissue dysplasia is diagnosed in cases where the patient's set of phenotypic traits does not fit into any of the differentiated syndromes. The reason is considered multifactorial effects on the fetus during fetal development, capable of causing defects in the genetic apparatus. Differentiation of such connective tissue structures as the spine, skin, valvular valves, large vessels occurs at the same time as fetal development, therefore the combination of dysplastic changes in these systems is most likely.
Undifferentiated connective tissue dysplasia plays a great aetiological role in the formation of neurocirculatory dysfunction. According to our data, about a third of the children surveyed for neurocirculatory dysfunction have a complex of DST symptoms. The initial background for its formation is the weakness of the subendothelial layer of the vessels, the developmental anomaly and the weakening of the vertebral ligament apparatus; in childbirth because of this, hemorrhages and injuries of the cervical spine are frequent. Juvenile osteochondrosis and high growth rate in the pubertal period increase blood flow disorders in the vertebrobasilar basin. A high incidence of allergic diseases, among which bronchial asthma prevails.
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