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The connective tissues are a challenging entity to define precisely
in isolation, as they are a component of every system of the body.
They can be characterized as an ordered array of cells and extracellular
matrix (specific protein fibers and amorphous ground substance).
From a functional perspective, connective tissues provide structure,
support, protection, delineate tissue boundaries, and serve as a
medium for cellular transport, nutrient exchange and storage and
play an especially significant role in the normal operation of skeletal,
dermatologic, cardiovascular, humoral, and sensory systems.
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From a histologic perspective, connective tissues are primarily
composed of an extracellular, proteinaceous substance or matrix
secreted from chief cells that populate the localized region. Connective
tissues are usually described by these chief cells and the matrix
they manufacture. The chief cells are almost entirely derived from
the mesoderm and include fibroblasts, osteocytes, chondrocytes,
mast cells, myocytes, lymphoid cells, adipose cells, macrophages,
and granulocytes. The many different forms of collagen account for the
vast majority of protein fibers that are found within the matrix.
Other important proteins include elastin, fibronectins, laminins,
and fibrillins. The amorphous ground substance is primarily composed
of glycosaminoglycans, proteoglycans, and glycoproteins.
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Disorders of connective tissue are segregated by their associated
medical complications and comorbid features. It is important to
realize that these manifestations (Table 181-1)
are nonspecific to an individual diagnosis and may present, to some
degree, within the entire community of these disorders. Having a
good knowledge base regarding the signs and symptoms of connective
tissue disease will enable the identification of individuals with
connective tissue disease and those who are potentially at medical
risk. The distinctive, recognizable syndromes will tend to have more
pronounced and medically important characteristics. In addition
to revised treatments of the Marfan and the Ehlers-Danlos syndromes,
the Stickler syndromes and the newly characterized Loeys-Dietz syndromes will
also be presented in this chapter.
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Marfan syndrome is a potentially life-threatening disorder with
cardinal features involving cardiovascular, skeletal, and ocular
systems as well as the dural coverings. It is caused by mutations ...