What type of collagen is defective in osteogenesis imperfecta?

What type of collagen is defective in osteogenesis imperfecta?

A reduction in type I collagen causes bones to be brittle and to fracture easily. The mutations that cause osteogenesis imperfecta types II, III, and IV occur in either the COL1A1 or COL1A2 gene. These mutations typically alter the structure of type I collagen molecules, resulting in abnormal type I collagen.

Which type of collagen is affected by mutations in osteogenesis imperfecta?

Osteogenesis Imperfecta types I through IV are caused by mutations in the COL1A1 or COL1A2 genes. These genes carry instructions for the production of type 1 collagen. Collagen is the major protein of bone and connective tissue including the skin, tendons and sclera.

What type of mutation is osteogenesis imperfecta?

About 80%–90% of OI cases are caused by autosomal dominant mutations in the type 1 collagen genes, COL1A1 and COL1A2. Mutations in one or the other of these genes cause the body to make either abnormally formed collagen or too little collagen.

What is the pathophysiology of osteogenesis imperfecta?

The most common form of OI is caused by mutations in the two collagen type I genes. Stop mutations usually lead to reduced collagen amount resulting in a mild phenotype, while missense mutations mainly provoke structural alterations in the collagen protein and entail a more severe phenotype.

Why does OI cause blue sclera?

Blue sclera is the most commonly known ocular sign for osteogenesis imperfecta and it is caused by thin scleral collagen allowing the underlying darker choroid vasculature to be seen. Patients with OI have shown a reduction in thickness of the corneal and scleral collagen fibers which can result in low ocular rigidity.

What is the cause of blue sclera?

Blue sclera: a bluish coloration of the whites of the eyes. The blue color is caused by thinness and transparency of the collagen fibers of the sclera, allowing the veins in the underlying tissue to show through. Blue sclerae are characteristic of a number of conditions, particularly connective tissue disorders.

What body systems are affected by osteogenesis imperfecta?

In more severe forms of osteogenesis imperfecta, there may be bone deformities, poor lung development and lung problems, a barrel-shaped chest, poor muscle development in the arms and legs. Osteogenesis imperfecta is caused by a faulty gene that affects the body’s ability to produce collagen.

Which types of the osteogenesis imperfecta are most common?

Type I: This is the mildest and most common form of OI. Type I leads to broken bones (bone fractures) or muscle weakness.

What research is being done on osteogenesis imperfecta?

Amgen is sponsoring a multicenter clinical trial to study the safety and efficacy of the investigational drug Denosumab on bone mineral and fracture occurrence in children who have OI. Currently, 34 sites in the United States and multiple other countries are participating in this clinical research study.

Does osteogenesis imperfecta cause blue eyes?

Osteogenesis imperfecta is predominantly known as a bone disease that can also have systemic manifestations. Blue sclera is the most commonly known ocular sign for osteogenesis imperfecta and it is caused by thin scleral collagen allowing the underlying darker choroid vasculature to be seen.

What is osteogenesis imperfecta type II (oII)?

Osteogenesis imperfecta type II is a lethal type of osteogenesis imperfecta (OI; see this term), a genetic disorder characterized by increased bone fragility, low bone mass and susceptibility to bone fractures. Patients with type II present multiple rib and long bone fractures at birth, marked deformities, broad long bones,…

Where can I find information about genetic testing for osteogenesis imperfecta?

GeneTests lists the names of laboratories that are performing genetic testing for different types of osteogenesis imperfecta. To view the contact information for the clinical laboratories conducting testing, click here and click on “Testing” next to the type of OI in which you are interested.

Is osteogenesis imperfecta autosomal dominant or recessive?

Osteogenesis imperfecta (OI) types I, II, III, IV, V and VI, are inherited in an autosomal dominant manner. This means that having only one changed (mutated) copy of the responsible gene in each cell is enough to cause features of OI.

What is the difference between IIc and OI Type IIa?

Type IIC is extremely rare and its existence is even doubted. OI type IIA is caused by mutations of the COL1A1 and COL1A2 genes (17q21.31-q22 and 7q22.1 respectively) and transmission is autosomal dominant.