Osteogenesis Imperfecta

Question 1

What are the Features of OI?

Answer 1

Low bone mass
Reduce bone mineral strength
Increase bone fragility
Increase bone deformity

Question 2

What are the features of Type 1 OI (Mild Form)?

Answer 2

Mild
Autosomal Dominant
Normal stature
Little or no deformity at birth
Blue sclerae
Hearing loss in 50% of families
Hypermobility of joints and increase bruising of thinner than normal skin
Aortic root dilation and mitral valve prolapse
IA-normal teeth, IB-dentinogenesis imperfecta

Question 3

What are the features of Type 1 OI fractures?

Answer 3

Fractures occur from walking through puberty and then again in 60s
Mostly long bones. Other bones possible.

Question 4

What are the features of Type 2 OI?

Answer 4

AD (rarely AR)
Lethal in perinatal period
Minimal calvarial mineralization
Beaded ribs 
Compressed femurs
Long bone deformity
Platyspondyly 
“Perinatal Leathal” OI

Question 5

What are the features of Type 3 OI “Progressive Deforming”?

Answer 5

AD (AR rare)
Progressively deforming bones
Some deformity at birth
Dentinogenesis imperfecta, blue sclera, hearing loss is common
Short stature
Long bones are short and curved with osteoperosis

Question 6

What are the similarities and differences of Type 1 and Type 3 OI?

Answer 6

Similarities → AD, blue sclera, hearing loss, dentinogenesis
Type 1 → no deformity at birth, normal stature, aortic dilatation and mitral prolapse
Type 3 → deformity at birth, short stature, long bones are short and curved

Question 7

What are the features of Type 4 Mild to Moderate Form OI?

Answer 7

AD
Normal sclera
Mild to moderate bone deformity
Variable short stature
Dentinogenesis imperfecta
Hearing loss in some
More fractures, more deformity, shorter than type 1
May present in adult women as “osteoperosis”
May be mistaken for child abuse → dentinogenesis imperfecta
Long bones are curved and short
Generalized osteoperosis
Scoliosis
Looks like Type 1 or Type 3

Question 8

What are presentation ages of Types 1, 3, 4?

Answer 8

type 1, 3 → < 1 y/o

type 4 → any age

Question 9

What is the mechanism of Osteogenesis Imperfecta?

Answer 9

Type 1 Collagen → skin, tendon, bone, arteries

trimer of two alpha-1 and one alpha-2 monomer
Alpha 1 → COL1A1 on chromo 17q
Alpha 2 → COLA2 on chromo 7q

• thin bones → ↓ periosteal formation, ↓ trabeculae

Question 10

What is Tx for Osteogenesis Imperfecta?

Answer 10

PT for strength
Orthosis for weight bearing
Surgical rod replacement for long bone curvature
Experimental
hGH in Type IV
Cell replacement in BM transplantation
Bisphosphanates

Question 11

When to suspect Osteogenesis Imperfecta?

Answer 11

recurrent fractures with minor trauma
Radiographs “washed out” bone
Unexplained osteoperosis, childhood-juvenile osteoperosis
Hearing loss, short stature, dentiogenesis imperfecta