Connective Tissue Disorders

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton, Elaine Lonnemann and Admin  

Introduction

The connective tissue disorders (CTDs) form a large heterogeneous group of conditions that are linked by a disease process that primarily involves the connective soft tissues of the body and often the vasculature too, due to shared structural proteins, such as collagen and elastin. There are over 200 documented disorders of connective tissue

Diseases of the connective tissue can be divided into

1. A group of relatively uncommon genetic disorders that affect the primary structure of connective tissue eg Marfan syndrome and osteogenesis imperfecta.
2. A number of acquired disorders in which the connective tissues are the site of several more or less distinctive immunological and inflammatory reactions eg rheumatoid arthritis, systemic lupus erythematosus, rheumatic fever, and osteoarthritis.

Anatomy & Physiology

A “tissue” in simple terms is a collection of similar cells. The human body is basically made of four different types of tissues.

1. Epithelial tissue
2. Connective tissue - the most abundant and diverse type of animal tissue
3. Muscular tissue
4. Nervous tissue.

Similar to a framework of a house, connective tissue serves to provide structure, support, and protection throughout the human body.

Connective tissue is an umbrella that encompasses a variety of tissue types, including loose and dense connective tissue, adipose, cartilage, bone, and blood. Although connective tissue is diverse, all connective tissue consists of three main components:

1. Ground substance
2. Fibers
3. Cells

Together, the ground substance and fibers make up the extracellular matrix, which is the structural support of surrounding cells throughout the body. The composition of the extracellular matrix varies tremendously from organ to organ, which allows for the diverse types of connective tissue.

Examples of Connective tissue:

• In the abdominal cavity, most organs are suspended from the abdominal wall by a membranous band (the mesentery) which is supported by connective tissue, others are embedded in adipose tissue (a form of connective tissue in which the cells are specialized for the synthesis and storage of energy-rich reserves of fat, or lipid).
• The entire body is supported from within by a skeleton composed of bone, a type of connective tissue endowed with great resistance to stress owing to its highly ordered laminated structure and to its hardness, which results from deposition of mineral salts in its fibres and amorphous matrix.
• The individual bones of the skeleton are held firmly together by ligaments, and muscles are attached to bone by tendons, both of which are examples of dense connective tissue in which many fibre bundles are associated in parallel array to provide great tensile strength.
• At joints, the articular surfaces of the bones are covered with cartilage, a connective tissue with an abundant intercellular substance that gives it a firm consistency well adapted to permitting smooth gliding movements between the apposed surfaces.
• The synovial membrane, which lines the margins of the joint cavity and lubricates and nourishes the joint surfaces, is also a form of connective tissue.
• Blood vessels, both large and small, course through connective tissue, which is therefore closely associated with the nourishment of tissues and organs throughout the body.

Hereditary Disorders Of Connective Tissue

Hereditary disorders of connective tissue are a heterogeneous group of generalized single-gene-determined disorders that affect one or another of the primary elements of the connective tissues (collagen, elastin, or ground substance [glycosaminoglycans]). Many cause skeletal and joint abnormalities that may interfere seriously with normal growth and development. These conditions are rare compared with the acquired connective tissue diseases. Examples include:

• Marfan syndrome
• Ehlers-Danlos syndrome
• osteogenesis imperfecta
• Stickler syndrome
• epidermolysis bullosa
• arterial tortuosity syndrome
• Loeys-Dietz syndrome

Acquired Diseases Of Connective Tissue

The acquired connective tissue diseases display certain common clinical features, including inflammation of the joints (polyarthralgia and arthritis), serous (fluid-exuding) membranes (pleurisy and pericarditis), and small blood vessels (vasculitis) and a high frequency of involvement of various internal organs that are particularly rich in connective tissue (e.g., the lungs). The walls of inflamed blood vessels, portions of which may become necrotic, are often found to contain characteristic deposits of hyaline (translucent) material called fibrinoid.

Classic connective tissue diseases

• systemic lupus erythematosus (SLE)
• systemic sclerosis (SSc)
• Sjogren syndrome (SS)
• mixed connective tissue disease (MCTD)
• polymyositis
• dermatomyositis

Seronegative connective tissue diseases

• ankylosing spondylitis
• psoriatic arthritis
• reactive arthritis
• enteropathic arthropathy

Resources

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References

• Dermatomyositis
• Ehlers-Danlos Syndrome
• Marfan Syndrome
• Polymyalgia Rheumatica