Osteogenesis Imperfecta

Question 1

What is osteogenesis imperfecta?

Answer 1

A brittle bone disease characterised by the bending of bone. It has both autosomal recessive and dominant forms and is a collagen type I related disease

Question 2

In classical AD osteogenesis imperfecta there is a mutation in what gene?

Answer 2

COL 1A1 or COL1A2

Question 3

What are the four types of AD osteogenesis imperfecta?

Answer 3

Type I mild non deforming
Type II perinatal lethal
Type III severe deforming
Type IV moderate deforming

Question 4

In which type of osteogenesis imperfecta is there no defect in collagen but merely a lack of collagen due to a lack of pro-alpha 1 chain?

Answer 4

Type I mild non deforming AD OI

Question 5

Which gene is mutated in recessive osteogenesis imperfecta?

Answer 5

SERPINH1 which codes for HSP 47

Question 6

How does a mutation in the gene for HSP 47 lead to osteogenesis imperfecta?

Answer 6

HSP binds to the triple helix collagen in the cell to stop it from aggregating until it has left the cell. A mutation stops HSP from functioning so collagen aggregates within the cell causing a delay in the secretion of collagen

Question 7

What type of mutation of glycine can cause osteogenesis imperfecta?

Answer 7

Dominant negative missense mutation of glycine