Osteogenesis imperfecta is disorder of bone formation. It is caused by an abnormality in the genes that control synthesis of bone components. The affected persons will frequently suffer multiple fractures when subjected to mild trauma or even in the absence of the same. In terms of epidemiology, the prevalence has been estimated to stand at 6 to 7 persons per 100,000 of population. The distribution is more or less the same worldwide.
At least 8 types of the disorder have been profiled to date. These are type I through VII. The different types have many overlapping features and a few differences in terms of signs and symptoms. Type I is regarded as the least severe and type II is the most severe. The rest are somewhere in-between. Studies are going on to try and establish the reason as to why some people are affected by one type and not the other.
In type I and all the other milder forms, bone fractures start in childhood and adolescence. In most cases there is preceding minor trauma. As the children grow into adulthood, the incidence of fractures is significantly reduced. The affected persons have a blue-grey tint on their sclera and often develop hearing loss later in adulthood. The height is usually normal in most cases.
The severe forms are associated with frequent bone fractures that typically start before birth without any predisposing factors. Other characteristics of the severe forms include blue sclerae, respiratory problems, abnormal teeth, hearing problems and a short stature. The respiratory problems are the result of extremely fragile ribs and underdeveloped lungs. Children may succumb shortly after birth due to respiratory distress.
Several studies have been carried out in an attempt to find the aetiological factors. The genes believed to carry the greatest responsibility in this disorder include CRTAP, COL1A1, COL1A2 and LEPRE1. Most cases of the conditions come about as a result of mutations that involve COL1A1 and COL1A2 genes. These are the genes that are responsible for the manufacture of collagen type 1 which is important in the integrity of connective tissues such as skin and bone.
The inheritance in this disorder is what is known as autosomal dominant pattern. This simply means that the disorder will manifest so long as one of the pairs of the copies of the gene pair involved in collagen synthesis is mutated. This is what is usually seen as regards collagen type I and IV. As for types II and III, there is no positive family history and the mutations are believed to be sporadic.
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.
At least 8 types of the disorder have been profiled to date. These are type I through VII. The different types have many overlapping features and a few differences in terms of signs and symptoms. Type I is regarded as the least severe and type II is the most severe. The rest are somewhere in-between. Studies are going on to try and establish the reason as to why some people are affected by one type and not the other.
In type I and all the other milder forms, bone fractures start in childhood and adolescence. In most cases there is preceding minor trauma. As the children grow into adulthood, the incidence of fractures is significantly reduced. The affected persons have a blue-grey tint on their sclera and often develop hearing loss later in adulthood. The height is usually normal in most cases.
The severe forms are associated with frequent bone fractures that typically start before birth without any predisposing factors. Other characteristics of the severe forms include blue sclerae, respiratory problems, abnormal teeth, hearing problems and a short stature. The respiratory problems are the result of extremely fragile ribs and underdeveloped lungs. Children may succumb shortly after birth due to respiratory distress.
Several studies have been carried out in an attempt to find the aetiological factors. The genes believed to carry the greatest responsibility in this disorder include CRTAP, COL1A1, COL1A2 and LEPRE1. Most cases of the conditions come about as a result of mutations that involve COL1A1 and COL1A2 genes. These are the genes that are responsible for the manufacture of collagen type 1 which is important in the integrity of connective tissues such as skin and bone.
The inheritance in this disorder is what is known as autosomal dominant pattern. This simply means that the disorder will manifest so long as one of the pairs of the copies of the gene pair involved in collagen synthesis is mutated. This is what is usually seen as regards collagen type I and IV. As for types II and III, there is no positive family history and the mutations are believed to be sporadic.
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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