written by: DulceCorazon•edited by: Paul Arnold•updated: 6/27/2011
Osteogenesis imperfecta, an inherited disease caused by genetic mutations affecting connective tissues in the body, has several types. This article focuses on type I osteogenesis imperfecta, its symptoms, diagnosis and the specific genes involved.
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Overview of Type I Osteogenesis Imperfecta
Type 1 osteogenesis imperfecta is one of the many subtypes of osteogenesis imperfecta, a hereditary condition brought about by genetic mutations exerting its effect on the production of type 1 collagen in the human body. It is the mildest form among the many types of osteogenesis imperfecta. And in some patients, it is so mild that the condition is not diagnosed until later in life. Other names of type I osteogenesis imperfecta are osteogenesis imperfecta tarda and Van der Hoeve syndrome.
The maintenance of bony structures and connective tissues in the body such as ligaments and tendons is the main responsibility of type 1 collagen. The production of Type I collagen depends on COL1A1 and COL1A2 genes. In the case of type 1 osteogenesis imperfecta, mutated COL1A1 and COL1A2 genes result in a decrease in the amount of type 1 collagen.
The decrease in type 1 collagen causes weakening of the bones, tendons, ligaments and other supporting structures in the body which translates to the signs and symptoms exhibited and felt by the patient with type 1 osteogenesis imperfecta. This genetic mutation does not cause abnormalities in the type 1 collagen but rather, it significantly decreases the amount produced. This is a differentiating characteristic of type 1 from the other types, since other forms of osteogenesis imperfecta result from abnormalities in the type 1 collagen itself.
Type I osteogenesis imperfecta is inherited through an autosomal dominant pattern. Simply put, one abnormal gene from one affected parent is enough for a child to inherit the condition. In some instances where neither parent is affected, the condition is acquired through new, spontaneous genetic mutations.
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Diagnosis and Clinical Manifestations
Since type 1 osteogenesis imperfecta is a hereditary condition, it is usually diagnosed through the patient’s family history. Other means used for diagnosis are biochemical tests conducted in the laboratory as well as DNA-sequencing. More importantly, the signs and symptoms manifested by the patient are taken into consideration when determining the type of osteogenesis imperfecta.
The signs and symptoms differ from one individual to another. Common among these are bones that fracture easily, blue sclerae, muscle weakness, a predisposition to dislocations, skin that tends to bruise easily, mild scoliosis, dental problems, growth problems, short limbs especially the legs, and hearing problems. The patient may also present with a large head and a face that resembles that of a triangle.
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The care of patients with type 1 osteogenesis imperfecta is mainly through the provision of support. Assistive devices, such as the use of wheelchair and walking aids, help prevent fractures brought about by falls. Physical and ccupational therapy, by means of safe exercises, proper nutrition and a healthy lifestyle, are cornerstones in the management of type 1 osteogenesis imperfecta.