Fibrous Extracellular Matrix Proteins

Question 1

Describe the main characteristics of osteogenesis imperfecta, “brittle bone disease”.

Answer 1

• Type I collagen mutation - often glycine > cysteine = disruption of alpha helix
• Autosomal dominant
• Hearing loss
• Blue sclera

Question 2

Describe the main characteristics of achondrogenesis.

Answer 2

• Type II collagen mutation
• Severe effects on development of cartilage and bones - e.g. lack of pelvic ossification

Question 3

Ehlers-Danlos syndrome, which features joint hypermobility, skin hyperextensibility, rupture of blood vessels and tissue fragility, is caused by what type of mutations?

Answer 3

Type III or type V collagen mutations

Question 4

In hypertension, there is increased deposition of what two substances in blood vessel walls?

Answer 4

Collagen and elastin

Question 5

Outline the pathophysiology of pulmonary emphysema.

Answer 5

• Loss of elastin - reduced elasticity of lungs
• Sometimes due to deficiency of α1-anti-trypsin
• α1-anti-trypsin normally inhibits elastase
• Too much elastase = excessive degradation

Question 6

Mutations in the fibrillin gene can cause what syndrome?

Answer 6

Marfan syndrome