Bone Disease Part 4 Flashcards
What are the 3 main congenital bone diseases
- Brittle bone disease (osteogenesis imperfecta)
- Achondroplasia
- Osteopetrosis
what is another name for brittle bone disease
osteogenesis Imperfecta
what is the cause of brittle bone disease
defective synthesis of collagen I and disruption of the structure of triple helix
what does brittle bone disease result in
results in fragile skeleton and too little bone
where are extra skeletal manifestations of brittle bone disease found
Extra skeletal manifestations of brittle bone disease found on: skin, joints, eyes: (blue sclera)
- How many types of brittle bone disease exist
4 types
describe the clinical outcome of type I brittle bone disease
increased childhood fractures (pre-puberty) but normal stature
describe the clinical outcome of type II brittle bone disease
fatality in utero or perinatal babies
describe the clinical outcome of type III brittle bone disease
can be progressive and deforming and short stature
describe the clinical outcome of type IV brittle bone disease
increased childhood fractures and short stature
- What causes achondroplasia
Caused by mutation on the fibroblast growth factor receptor 3 resulting in activation
what are genetic features of achondroplasia
(autosomal dominant and heterozygous)
What does FGFR3 activation result in
FGFR3 activation inhibits chondrocyte proliferation: affects growth plates
- What happens to the growth plates in achondroplasia
Growth plates are disorganised and hypoplastic
- What bones are affected by achondroplasia
All bones that develop by endochondral ossification are affected
In what 4 ways does achondroplasia affect stature?
- Short stature with stunted extremities (esp. proximal)
- bowed legs
- frontal bossing
- pronounced lordosis/kyphosis
- How is osteopetrosis characterised
by high bone mass
- How do you get osteopetrosis
It is inherited
- Why does osteopetrosis happen and what does this lead to?
happens due to interference with osteoclast formation and differentiation directly affecting their action, leading to defective bone remodelling
- what are features of bones affected by osteopetrosis
Dense ‘stone bone’ but brittle and easily fractured
- What does deposited bone stay as?
Remain as woven bone
- Give 4 clinical effects of osteopetrosis
- fractures
- spinal nerve compression (excess bone)
- recurrent infection (reduced bone marrow cavity).
- Hepatosplenomegaly
why does hepatosplenomegaly happen in osteoporosis
happens due to haematopoiesis outside the bone.
How can osteopetrosis be treated
Bone marrow transplant to provide healthy osteoclast precursors
