Osteogenesis Imperfecta

Question 1

What molecule is not working as expected in OI?

Answer 1

Collagen
Mild - not enough strands
Severe - strands are made wrong

Question 2

Put the four types of OI in order from most to least severe

Answer 2

II - Perinatal Lethal
III - Progressively deforming OI
IV - Common variable OI with normal sclerae
I - Classic non-deforming OI with blue sclerae

Question 3

Clinical features of classic non-deforming OI with blue sclerae

Answer 3

few to 100s of fractures, nondeforming
blue sclerae
could have dentiogenesis imperfecta
normal stature
joint hypermobility
progressive hearing loss

Question 4

Etiology of OI Type I

Answer 4

AD
Nonsense mutation in COL1A1 or COL1A2

60% simplex cases

Question 5

T/F: In inherited cases of OI Type I, parents sometimes come to attention when their child is diagnoses

Answer 5

T - OI Type I can present quite mildly

Question 6

Clinical features of OI Type II (Perinatal Lethal)

Answer 6

multiple fractures prior to birth, birth trauma can also cause many fractures
deformed bones, small chest (leads to pulmonary insufficiency)

Question 7

Mortality rate of OI Type II

Answer 7

60% day 1

80% week 1

Question 8

What kinds of mutations cause OI Type II

Answer 8

mutations changing the structure in the middle or near the C-terminus of the molecule leading to abnormal collagen incorporation in bone

Question 9

Inheritance of OI Type II

Answer 9

new AD mutation

some overlap with AR versions –> family and pregnancy history is important

Question 10

What is the RR for OI Type II?

Answer 10

7% (gonadal mosaicism)

Question 11

Clinical features of OI Type III

Answer 11

deforming, progressive
short stature
may have significant fractures and deformities at birth
NO pulmonary insufficiency
sclerae slightly blue (can normalize overtime)