What Is Kniest Chondrodystrophy?
Kniest Chondrodystrophy which is also known by the name of Kniest Dysplasia is a genetic condition which is characterized by dwarfism. This condition is caused by mutation in gene COL2A1. The function of this gene is to produce a protein which forms collagen II which is responsible for normal development of bones and connective tissues. An abnormality in the production of collagen II leads to abnormal skeletal growth including a variety of dwarfism which is the characteristic feature of Kniest Chondrodystrophy.
Short stature is the primary presenting feature of Kniest Chondrodystrophy. Additionally, the affected individual might also have abnormally large knees and cleft palate which can be seen at birth. The other characteristics may be visible only after two to three years of life of the child with Kniest Chondrodystrophy.
What Causes Kniest Chondrodystrophy?
As stated above, the root cause for the development of Kniest Chondrodystrophy is the mutation in the gene COL2A1. This gene produces collagen II which is responsible for normal growth and development of bones and connective tissues.
This condition follows an autosomal dominant pattern of inheritance meaning that one copy of the defective gene from either parent is good enough for the development of Kniest Chondrodystrophy.
In some cases there may be de novo mutations meaning that there is mutation in gene for no reason and it occurs spontaneously leading to the development of Kniest Chondrodystrophy.
What Are The Symptoms Of Kniest Chondrodystrophy?
The primary symptom of Kniest Chondrodystrophy is the affected individual will be of abnormally short height. There will be visible deformity of the upper and lower extremities, a barrel shaped chest and an abnormally long trunk.
As the child grows the abnormally long trunk takes the shape of a curvature of the spine. There are also certain ocular abnormalities in individuals with Kniest Chondrodystrophy. Such individuals tend to have protruding eyes with low nasal bridge.
Additionally, the individual may have myopia along with drooping of the eyelids, and in some cases even blindness which may be partial or complete. There can also be detachment of the retina and lens dislocations.
Cataracts are also one of the common findings in individuals with Kniest Chondrodystrophy. There is also presence of a cleft palate along with speech impairments which may come into light when the child is at the age where he or she begins to speak.
Musculoskeletal wise, the individual may have contracted hips which can make walking difficult for the individual. There may also be flattening of the vertebrae of the spine.
Inguinal and umbilical hernias may also be seen in individuals with Kniest Chondrodystrophy. Hearing loss and delayed motor development is also one of the characteristic features of Kniest Chondrodystrophy.
How Is Kniest Chondrodystrophy Diagnosed?
The characteristic presenting features of this condition at the time of birth including abnormally large trunk and extremities is a big give away when it comes to the diagnosis of Kniest Chondrodystrophy.
Once this condition is suspected, a molecular testing can be done which will clearly show mutations in the COL2A1 which will confirm the diagnosis of Kniest Chondrodystrophy. Additionally advanced imaging in the form of CT and MRI scans also aid in confirming the diagnosis of Kniest Chondrodystrophy.
How Is Kniest Chondrodystrophy Treated?
The main aim of treatment for Kniest Chondrodystrophy is to correct the visible deformities that the child has. This includes stabilization of the joints that are lax. For this, the child may have to undergo a variety of surgical procedures.
Surgery may also be required to treat detached retina and other ocular abnormalities found in Kniest Chondrodystrophy. Cleft palate may also be treated with surgery. Other than this, the treatment is only symptomatic and supportive for Kniest Chondrodystrophy.