Kniest syndrome

Kniest dysplasia is a rare form of dwarfism caused by a mutation in the COL2A1 gene on chromosome 12. The COL2A1 gene is responsible for producing type II collagen. The mutation of COL2A1 gene leads to abnormal skeletal growth and problems with hearing and vision. What characterizes Kniest dysplasia from other type II osteochondrodysplasia is the level of severity and the dumb-bell shape of shortened long tubular bones. Kniest dysplasia is a rare form of dwarfism caused by a mutation in the COL2A1 gene on chromosome 12. The COL2A1 gene is responsible for producing type II collagen. The mutation of COL2A1 gene leads to abnormal skeletal growth and problems with hearing and vision. What characterizes Kniest dysplasia from other type II osteochondrodysplasia is the level of severity and the dumb-bell shape of shortened long tubular bones. This condition was first diagnosed by Dr. Wilhelm Kniest in 1952. Dr. Kniest noticed that his 50-year-old patient was having difficulties with restricted joint mobility. The patient had a short stature and was also suffering from blindness. Upon analysis of the patient's DNA, Dr. Kniest discovered that a mutation had occurred at a splice site of the COL2A1 gene. This condition is very rare and occurs less than 1 in 1,000,000 people. Males and females have equal chances of having this condition. Currently, there is no cure for Kniest dysplasia. Alternative names for Kniest Dysplasia can include Kniest syndrome, swiss cheese cartilage syndrome, Kniest chondrodystrophy, or metatrophic dwarfism type II. Because collagen plays an important role in the development of the body, people with Kniest Dysplasia will typically have their first symptoms at birth. These symptoms can include:. Most symptoms are chronic and will continue to worsen as the individual ages. It is essential to have regular checkups with general doctors, orthopedist, ophthalmologists, and/or otorhinolaryngologists. This will help to detect whether there are any changes that could cause concern. Studies have shown that a mutated COL2A1 gene is responsible for all type II chondroldysplasias, including Kniest dysplasia. It is believed that point mutations or the alteration of splice sites in COL2A1 domains will result in Kniest Dysplasia. The COL2A1 domain typically spans between exon 12 and 24. Mutations that occur at a splice donor site results in the loss of function at that site. This leads to the skipping of the exon and deletion of amino acids. The loss of these amino acids result in an abnormal procollagen II structure. The structure is not stable like the normal procollagen II structure and is normally degraded at a faster rate. Kniest dysplasia is an autosomal dominant condition. This means that the person only needs to have one copy of the mutated gene in order to have the condition. People with a family history are at a higher risk of having the disease than people with no family history. A random mutation in the gene can cause a person with no family history to also have the condition. A combination of medical tests are used to diagnosis Kniest dysplasia. These tests can include: The images taken will help to identify any bone anomalies. Two key features to look for in a patient with Kniest dysplasia is the presence of dumb-bell shaped femur bones and coronal clefts in the vertebrae. Other features to look for include: