Spondyloperipheral dysplasia is an

autosomal An autosome is any chromosome that is not a sex chromosome. The members of an autosome pair in a diploid cell have the same morphology, unlike those in allosomal (sex chromosome) pairs, which may have different structures. The DNA in autosomes ...

dominant disorder of

bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, an ...

growth. The condition is characterized by flattened bones of the spine (

platyspondyly Congenital vertebral anomalies are a collection of malformations of the spine. Most, around 85%, are not clinically significant, but they can cause compression of the spinal cord by deforming the vertebral canal or causing instability. This condi ...

) and unusually short fingers and toes (

brachydactyly Brachydactyly (Greek βραχύς = "short" plus δάκτυλος = "finger"), is a medical term which literally means "short finger". The shortness is relative to the length of other long bones and other parts of the body. Brachydactyly is an in ...

). Some affected individuals also have other skeletal abnormalities, short stature, nearsightedness (

myopia Near-sightedness, also known as myopia and short-sightedness, is an eye disease where light focuses in front of, instead of on, the retina. As a result, distant objects appear blurry while close objects appear normal. Other symptoms may include ...

), hearing loss, and

mental retardation Intellectual disability (ID), also known as general learning disability in the United Kingdom and formerly mental retardation, Rosa's Law, Pub. L. 111-256124 Stat. 2643(2010). is a generalized neurodevelopmental disorder characterized by signif ...

. Spondyloperipheral dysplasia is a subtype of collagenopathy, types II and XI.

Genetics

Spondyloperipheral dysplasia is one of a spectrum of skeletal disorders caused by mutations in the ''

COL2A1 Collagen, type II, alpha 1 (primary osteoarthritis, spondyloepiphyseal dysplasia, congenital), also known as COL2A1, is a human gene that provides instructions for the production of the pro-alpha1(II) chain of type II collagen. Function This g ...

gene In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...

, located on

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...

12q13.11-q13.2. The protein made by this gene forms type II collagen, a molecule found mostly in cartilage and in the clear gel that fills the

vitreous humour The vitreous body (''vitreous'' meaning "glass-like"; , ) is the clear gel that fills the space between the lens and the retina of the eyeball (the vitreous chamber) in humans and other vertebrates. It is often referred to as the vitreous humo ...

(the eyeball). Type II collagen is essential for the normal development of bones and other connective tissues (the tissues that form the body's supportive framework). Mutations in the ''COL2A1'' gene interfere with the assembly of type II collagen molecules. The protein made by the altered ''COL2A1'' gene cannot be used to make type II collagen, resulting in a reduced amount of this type of collagen in the body. Instead of forming collagen molecules, the abnormal protein builds up in cartilage cells (

chondrocytes Chondrocytes (, from Greek χόνδρος, ''chondros'' = cartilage + κύτος, ''kytos'' = cell) are the only cells found in healthy cartilage. They produce and maintain the cartilaginous matrix, which consists mainly of collagen and prote ...

). These changes disrupt the normal development of bones, leading to the signs and symptoms of spondyloperipheral dysplasia. The disorder is believed to be inherited in an autosomal dominant manner. This indicates that the defective gene responsible for the disorder is located on an autosome (chromosome 12 is an autosome), and only one copy of the defective gene is sufficient to cause the disorder, when inherited from a parent who has the disorder.

Diagnosis

Management

References

''This article incorporates public domain text from ''

External links

* {{Scleroprotein disease Congenital disorders Autosomal dominant disorders Skeletal disorders Rare diseases