Osteogenesis imperfecta is a disorder of bone that results from abnormalities in a group of genes that code for bone formation. The bones formed are weak and break very easily. Consequently, affected persons will frequently suffer multiple injuries following mild trauma or just spontaneously. It is estimated that close to 7 people are affected per 100,000 of population. The distribution is almost the same worldwide.
There are about eight types of the conditions which are designated type I to type VIII. There are mild differences in signs and symptoms that characterize the different types. Type is the mildest of them all while type II is the most severe; the rest are somewhere between these two. There is on-going research that seeks to identify the genetic factors that are responsible for these differences.
In the mild form such as type I, affected individuals start getting bone fractures early in childhood, adolescence and teenage. In most cases, there is predisposing minor trauma. As they grow older the incidence of fractures is significantly reduced. Accompanying features include hearing loss and a blue-grey tint on the sclera. Height is rarely affected.
In the severe forms, the frequency of fractures is much higher. The problem starts even before the child is born. They suffer multiple fractures while still in the uterus usually without any predisposing trauma. There are other accompanying features that include abnormal teeth, blue sclerae, short stature and respiratory problems. The respiratory problems are caused by fragile ribs and the presence of underdeveloped lungs.
A lot of studies have been carried out in this area. In terms of genetics the genes believed to be responsible for the abnormality include COL1A1, COL1A2, LEPRE1 and CRTAP. Mutations affecting the COL1A1 and COL1A2 alone are responsible for more than 90% of the cases. These genes code for proteins that are required for the synthesis of collagen type 1. This collagen is very important in the integrity of skin and bone as well as other connective tissues.
The type of inheritance pattern that is seen in this condition is what is known as autosomal dominant inheritance. In this kind of inheritance diseases are inherited when a copy of a gene in a pair is mutated as opposed to the autosomal recessive where both copies in the pair have to be mutated. This is the case with types IV and I. Types II and III come about as a result of sporadic gene mutations.
There is no definitive treatment for this disorder at present. The available modes of management are aimed at strengthening the bones so as to reduce the incidence of fractures. The drug alendronate, a bisphosphonate, has undergone several clinical trials to check for its effectiveness but the results are still inconclusive. Other conservative measures include engagement in weight bearing exercises regularly and increasing the intake of calcium and vitamin D. Bone infections should be treated promptly.
Other treatments that have been considered for management of osteogenesis imperfecta include physiotherapy, the use of physical aids and surgery. Physiotherapy is done to improve motility and to minimize fracture risks. The physical aids that can be used include wheelchairs, splints, crutches and grabbing arms. Surgical options include insertion of metallic rods in the long bones and spinal fusion to correct deformities such as scoliosis.
There are about eight types of the conditions which are designated type I to type VIII. There are mild differences in signs and symptoms that characterize the different types. Type is the mildest of them all while type II is the most severe; the rest are somewhere between these two. There is on-going research that seeks to identify the genetic factors that are responsible for these differences.
In the mild form such as type I, affected individuals start getting bone fractures early in childhood, adolescence and teenage. In most cases, there is predisposing minor trauma. As they grow older the incidence of fractures is significantly reduced. Accompanying features include hearing loss and a blue-grey tint on the sclera. Height is rarely affected.
In the severe forms, the frequency of fractures is much higher. The problem starts even before the child is born. They suffer multiple fractures while still in the uterus usually without any predisposing trauma. There are other accompanying features that include abnormal teeth, blue sclerae, short stature and respiratory problems. The respiratory problems are caused by fragile ribs and the presence of underdeveloped lungs.
A lot of studies have been carried out in this area. In terms of genetics the genes believed to be responsible for the abnormality include COL1A1, COL1A2, LEPRE1 and CRTAP. Mutations affecting the COL1A1 and COL1A2 alone are responsible for more than 90% of the cases. These genes code for proteins that are required for the synthesis of collagen type 1. This collagen is very important in the integrity of skin and bone as well as other connective tissues.
The type of inheritance pattern that is seen in this condition is what is known as autosomal dominant inheritance. In this kind of inheritance diseases are inherited when a copy of a gene in a pair is mutated as opposed to the autosomal recessive where both copies in the pair have to be mutated. This is the case with types IV and I. Types II and III come about as a result of sporadic gene mutations.
There is no definitive treatment for this disorder at present. The available modes of management are aimed at strengthening the bones so as to reduce the incidence of fractures. The drug alendronate, a bisphosphonate, has undergone several clinical trials to check for its effectiveness but the results are still inconclusive. Other conservative measures include engagement in weight bearing exercises regularly and increasing the intake of calcium and vitamin D. Bone infections should be treated promptly.
Other treatments that have been considered for management of osteogenesis imperfecta include physiotherapy, the use of physical aids and surgery. Physiotherapy is done to improve motility and to minimize fracture risks. The physical aids that can be used include wheelchairs, splints, crutches and grabbing arms. Surgical options include insertion of metallic rods in the long bones and spinal fusion to correct deformities such as scoliosis.
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