Osteogenesis Imperfecta (OI)

Question 1

What is OI?

Answer 1

• Inherited connective tissue disorder characterized by bone fragility and fractures
• OI refers to a broad range of clinical presentations that may be first apparent from early in pregnancies to late in life
• The extent of bone deformity and fracture predisposition is variable

Question 2

Other symptoms of OI

Answer 2

• Blue sclerae
• Adult onset hearing loss
• Joint laxity
• Short stature
• Dentinogenesis imperfecta (DI)

Question 3

Inheritance pattern in OI

Answer 3

• Autosomal dominant, however, new mutations are common and recessive inheritance does occur

Question 4

Genes responsible for ~90% of OI cases

Answer 4

• COL1A1
• COL1A2
  (encode the chains of type I collagen, the major protein of bone)

Question 5

OI Type II

Answer 5

Lethal perinatal type (can detect on U/S at 14 weeks +)

Question 6

Type of OI that is Autosomal Recessive

Answer 6

OI type VII

Question 7

Laboratory testing for OI

Answer 7

• For pregnancies at risk for most forms of OI on basis of family history:
• Biochemical analysis of type I collagen from cultured CVS cells can be offered if collage screening studies have been completed on the affected parent or previous affected infant