COL11A2 is a human
Humans are the only living species in the Homo genus...

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...

 that is one of several genes that provide instructions for the production of type XI collagen. The COL11A2 gene produces one component of this type of 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...

, called the pro-alpha2(XI) chain. Type XI collagen adds structure and strength to the tissues that support the body's muscle
Muscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...

s, joint
A joint is the location at which two or more bones make contact. They are constructed to allow movement and provide mechanical support, and are classified structurally and functionally.-Classification:...

s, organ
Organ (anatomy)
In biology, an organ is a collection of tissues joined in structural unit to serve a common function. Usually there is a main tissue and sporadic tissues . The main tissue is the one that is unique for the specific organ. For example, main tissue in the heart is the myocardium, while sporadic are...

s and skin
Human skin
The human skin is the outer covering of the body. In humans, it is the largest organ of the integumentary system. The skin has multiple layers of ectodermal tissue and guards the underlying muscles, bones, ligaments and internal organs. Human skin is similar to that of most other mammals,...

 (the connective tissue
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...

). Type XI collagen is normally found in 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...

, the tissue that cushions bones and joints and makes up the flexible portions of the nose
Human nose
The visible part of the human nose is the protruding part of the face that bears the nostrils. The shape of the nose is determined by the ethmoid bone and the nasal septum, which consists mostly of cartilage and which separates the nostrils...

 and ear
The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....

s. It is also part of 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 inner ear, and the center portion of the discs between the vertebrae in the spine (nucleus pulposus
Nucleus pulposus
Nucleus pulposus is the jelly-like substance in the middle of the spinal disc. It is the remnant of the notochord . It functions to distribute hydraulic pressure in all directions within each disc under compressive loads. The nucleus pulposus consists of chondrocyte-like cells, collagen fibrils,...

). Type XI collagen also helps maintain the spacing and diameter of type II collagen fibrils. Type II collagen is an important component of the eye and mature cartilage tissue. The size and arrangement of type II collagen fibrils is essential for the normal structure of these tissues.

The pro-alpha2(XI) chain combines with pro-alpha1(XI) and pro-alpha1(II)collagen chains to form a procollagen molecule. These triple-stranded, ropelike procollagen molecules must be processed by enzymes in the cell. Once processed, these procollagen molecules leave the cell and arrange themselves into long, thin fibrils that cross-link to one another in the spaces around cells. The cross-linkages result in the formation of very strong mature type XI collagen fibers.

The COL11A2 gene is located on the short (p) arm of chromosome 6
Chromosome 6 (human)
Chromosome 6 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 6 spans more than 170 million base pairs and represents between 5.5 and 6% of the total DNA in cells...

 at position 21.3, from base pair
Base pair
In molecular biology and genetics, the linking between two nitrogenous bases on opposite complementary DNA or certain types of RNA strands that are connected via hydrogen bonds is called a base pair...

 33,238,446 to base pair 33,268,222.

Related conditions

Nonsyndromic deafness, autosomal dominant: Mutations in the COL11A2 gene have been shown to cause hearing loss without other signs or symptoms (nonsyndromic deafness) in two large families. One family carries a mutation that substitutes the amino acid cysteine (a building block of proteins) for the amino acid arginine at position 549 (written as Arg549Cys) in the alpha 2 chain of type XI collagen. A second family has a mutation that substitutes the amino acid glutamic acid for the amino acid glycine at position 323 (written as Gly323Glu) in this protein. These mutations prevent the normal assembly of type XI collagen. Type XI collagen plays an important role in the structure and function of the inner ear. When mutations in the COL11A2 gene affect the structure of collagen fibrils, hearing loss can result.

Otospondylomegaepiphyseal dysplasia
Otospondylomegaepiphyseal dysplasia
Otospondylomegaepiphyseal dysplasia is an autosomal recessive disorder of bone growth that results in skeletal abnormalities, severe hearing loss, and distinctive facial features...

: Approximately 10 mutations identified in the COL11A2 gene are responsible for otospondylomegaepiphyseal dysplasia (OSMED). Most of these mutations result in a complete lack of pro-alpha2(XI) chains, which leads to a loss of function of type XI collagen. Some mutations affect the production of the pro-alpha2(XI) chain and disrupt normal collagen assembly. Because this type of collagen is an important component of cartilage and other connective tissues, these mutations result in the characteristic signs and symptoms of OSMED.

Stickler syndrome, COL11A2: Stickler syndrome
Stickler syndrome
Stickler 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...

 is a disorder that causes problems with skeletal development, vision, and hearing. Mutations in the COL11A2 gene cause a form of Stickler in which vision is not affected. COL11A2 mutations cause abnormal production of the pro-alpha2(XI) chain, part of type XI collagen. As a result, type XI collagen is impaired and cannot function properly, causing the skeletal and hearing problems characteristic of Stickler syndrome. The pro-alpha2(XI) chain, however, is not made in the eyes. Instead, another type of collagen chain replaces pro-alpha2(XI) to form type XI collagen in the vitreous of the eye. COL11A2 mutations, therefore, do not affect vision.

Weissenbacher-Zweymüller syndrome
Weissenbacher-Zweymüller syndrome
Weissenbacher–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...

: At least one identified mutation in the COL11A2 gene is responsible for Weissenbacher-Zweymüller syndrome. This mutation causes the amino acid glycine to be replaced with the amino acid glutamic acid at position 955 in the alpha 2 chain of type XI collagen (written as Gly955Glu). This mutation prevents collagen molecules from being assembled properly, which disrupts the structure of type XI collagen. These changes result in the characteristic signs and symptoms of Weissenbacher-Zweymüller syndrome.

External links

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