Collagenopathy, types II and XI
Encyclopedia
The type II and XI collagenopathies are a group of disorders that affect connective tissue
, the tissue that supports the body's joints and organs. These disorders are caused by defects in type II or type XI collagen
. Collagens are complex molecules that provide structure, strength, and elasticity to connective tissue. Type II and type XI collagen disorders are grouped together because both types of collagen are components of the cartilage
found in joints and the spinal column, the inner ear, and the jelly-like substance that fills the eyeball (the vitreous
). The type II and XI collagenopathies result in similar clinical features.
The system for classifying collagenopathies is changing as researchers learn more about the genetic causes of these disorders.The clinical features of the type II and XI collagenopathies vary among the disorders, but there is considerable overlap. Common signs and symptoms include problems with bone
development that can result in short stature, enlarged joints, spinal curvature, and arthritis
at a young age. For some people, bone changes can be seen only on X-ray
images. Problems with vision and hearing, as well as a cleft palate with a small lower jaw, are common. Some individuals with these disorders have distinctive facial features such as protruding eyes and a flat nasal bridge.
s cause collagenopathy, types II and XI. These genes carry instructions for the protein strands that make up type II and type XI collagen. All collagen molecules are made of three protein strands (called alpha chains). The alpha chains may be identical or different, depending on the type of collagen. Type II collagen is made by combining three copies of the alpha chain made by the COL2A1 gene. Type XI collagen, on the other hand, is composed of three different alpha chains: the products of the COL2A1, COL11A1, and COL11A2 genes.
Mutations in these genes interfere with the proper assembly of type II and XI collagens or reduce the amount of these collagens. Defective or reduced numbers of collagen molecules affect the development of bones and other connective tissues, causing the signs and symptoms of the type II and XI collagenopathies.
This article incorporates public domain text from The U.S. National Library of Medicine
Connective tissue
"Connective tissue" is a fibrous tissue. It is one of the four traditional classes of tissues . Connective Tissue is found throughout the body.In fact the whole framework of the skeleton and the different specialized connective tissues from the crown of the head to the toes determine the form of...
, the tissue that supports the body's joints and organs. These disorders are caused by defects in type II or type XI collagen
Collagen
Collagen is a group of naturally occurring proteins found in animals, especially in the flesh and connective tissues of mammals. It is the main component of connective tissue, and is the most abundant protein in mammals, making up about 25% to 35% of the whole-body protein content...
. Collagens are complex molecules that provide structure, strength, and elasticity to connective tissue. Type II and type XI collagen disorders are grouped together because both types of collagen are components of the cartilage
Cartilage
Cartilage is a flexible connective tissue found in many areas in the bodies of humans and other animals, including the joints between bones, the rib cage, the ear, the nose, the elbow, the knee, the ankle, the bronchial tubes and the intervertebral discs...
found in joints and the spinal column, the inner ear, and the jelly-like substance that fills the eyeball (the vitreous
Vitreous humour
The vitreous humour or vitreous humor is the clear gel that fills the space between the lens and the retina of the eyeball of humans and other vertebrates...
). The type II and XI collagenopathies result in similar clinical features.
Types
Genetic changes are related to the following types of collagenopathy, types II and XI.- achondrogenesis type 2Achondrogenesis type 2Infants with achondrogenesis, type 2 have short arms and legs, a small chest with short ribs, and underdeveloped lungs. Achondrogenesis, type 2 is a subtype of collagenopathy, types II and XI. This condition is also associated with a lack of bone formation in the spine and pelvis...
- hypochondrogenesisHypochondrogenesisHypochondrogenesis is a severe genetic disorder causing malformations of bone growth. The condition is characterized by a short body and limbs and abnormal bone formation in the spine and pelvis....
- Kniest dysplasiaKniest dysplasiaKniest dysplasia is an uncommon inherited disorder of bone growth. The condition is characterized by dwarfism, enlarged joints, and other skeletal abnormalities, and problems with vision and hearing...
- otospondylomegaepiphyseal dysplasiaOtospondylomegaepiphyseal dysplasiaOtospondylomegaepiphyseal dysplasia is an autosomal recessive disorder of bone growth that results in skeletal abnormalities, severe hearing loss, and distinctive facial features...
- spondyloepimetaphyseal dysplasia, Strudwick typeSpondyloepimetaphyseal dysplasia, Strudwick typeSpondyloepimetaphyseal dysplasia, Strudwick type is an inherited disorder of bone growth that results in dwarfism, characteristic skeletal abnormalities, and problems with vision. The name of the condition indicates that it affects the bones of the spine and two regions near the ends of bones...
- spondyloepiphyseal dysplasia congenitaSpondyloepiphyseal dysplasia congenitaSpondyloepiphyseal dysplasia congenita is a rare disorder of bone growth that results in dwarfism, characteristic skeletal abnormalities, and occasionally problems with vision and hearing...
- spondyloperipheral dysplasiaSpondyloperipheral dysplasiaSpondyloperipheral dysplasia is an autosomal dominant disorder of bone growth. The condition is characterized by flattened bones of the spine and unusually short fingers and toes . Some affected individuals also have other skeletal abnormalities, short stature, nearsightedness , hearing loss, and...
- Stickler syndromeStickler syndromeStickler syndrome is a group of genetic disorders affecting connective tissue, specifically collagen. It was first studied and characterized by Gunnar B. Stickler in 1965. Stickler syndrome is a subtype of collagenopathy, types II and XI...
- Weissenbacher-Zweymüller syndromeWeissenbacher-Zweymüller syndromeWeissenbacher–Zweymuller syndrome , also called Pierre-Robin syndrome with fetal chondrodysplasia, is an autosomal recessive congenital disorder, linked to mutations in the COL11A2 gene , which codes for the α2 strand of collagen type XI...
The system for classifying collagenopathies is changing as researchers learn more about the genetic causes of these disorders.The clinical features of the type II and XI collagenopathies vary among the disorders, but there is considerable overlap. Common signs and symptoms include problems with bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
development that can result in short stature, enlarged joints, spinal curvature, and arthritis
Arthritis
Arthritis is a form of joint disorder that involves inflammation of one or more joints....
at a young age. For some people, bone changes can be seen only on X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
images. Problems with vision and hearing, as well as a cleft palate with a small lower jaw, are common. Some individuals with these disorders have distinctive facial features such as protruding eyes and a flat nasal bridge.
Causes
Mutations in the COL11A1, COL11A2, and COL2A1 geneGene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
s cause collagenopathy, types II and XI. These genes carry instructions for the protein strands that make up type II and type XI collagen. All collagen molecules are made of three protein strands (called alpha chains). The alpha chains may be identical or different, depending on the type of collagen. Type II collagen is made by combining three copies of the alpha chain made by the COL2A1 gene. Type XI collagen, on the other hand, is composed of three different alpha chains: the products of the COL2A1, COL11A1, and COL11A2 genes.
Mutations in these genes interfere with the proper assembly of type II and XI collagens or reduce the amount of these collagens. Defective or reduced numbers of collagen molecules affect the development of bones and other connective tissues, causing the signs and symptoms of the type II and XI collagenopathies.
This article incorporates public domain text from The U.S. National Library of Medicine