Kniest dysplasia is one of several forms of dwarfism that is caused by a change (mutation) in a gene known as COL2A1. This gene is involved in the production of a particular protein that forms type 2 collagen, which is essential for the normal development of bones and other connective tissue. Changes in the composition of type 2 collagen lead to abnormal skeletal growth and, thus, to a variety of dwarfing conditions known as skeletal dysplasias.
Some of the signs and symptoms of Kniest dysplasia, such as short stature, enlarged knees, and cleft palate, are usually present at birth. Other characteristics may not appear for two or three years.
Kniest dysplasia is one of a spectrum of skeletal disorders caused by mutations in the COL2A1 gene. This gene provides instructions for making a protein that forms type II collagen. This type of collagen is found mostly in the clear gel that fills the eyeball (the vitreous) and in cartilage. Cartilage is a tough, flexible tissue that makes up much of the skeleton during early development. Most cartilage is later converted to bone, except for the cartilage that continues to cover and protect the ends of bones and is present in the nose and external ears. Type II collagen is essential for the normal development of bones and other connective tissues that form the body's supportive framework.
Most mutations in the COL2A1 gene that cause Kniest dysplasia interfere with the assembly of type II collagen molecules. Abnormal collagen prevents bones and other connective tissues from developing properly, which leads to the signs and symptoms of Kniest dysplasia.
The COL2A1 gene is located on the long (q) arm of chromosome 12 at position 13.11.
More precisely, the COL2A1 gene is located from base pair 47,972,964 to base pair 48,004,553 on chromosome 12.
Read more about the COL2A1 gene.
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
In some cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.
The signs and symptom information on this page attempts to provide a list of some possible signs and symptoms of Kniest dysplasia. This medical information about signs and symptoms for Kniest dysplasia has been gathered from various sources, may not be fully accurate, and may not be the full list of Kniest dysplasia signs or Kniest dysplasia symptoms. Furthermore, signs and symptoms of Kniest dysplasia may vary on an individual basis for each patient. Only your doctor can provide adequate diagnosis of any signs or symptoms and whether they are indeed Kniest dysplasia symptoms.