Which of the following pediatric congenital disorders is caused by a glycine substitution in the procollagen molecule?

a. Scurvy

b. Osteogenesis imperfecta

c. Ochronosis

d. Fibrous dysplasia



Synonyms =

  • Ø fragilitas ossium
  • Ø Osteopsathyrosis
  • Ø Lobstein’s disease
  • Ø Vrolik’s disease
  • Ø Brittle bone disease


The disease is mainly due to defect in type 1 Collagen due to glycine substitution in the pro collagen molecule


Triad of OI =

  • Ø Blue Sclerae
  • Ø Dentinogenesis imperfect
  • Ø Generalized osteoporosis


Classification = ( Shapiro et al )

  • Ø Congenita A ( fractures in utero / birth with 100% mortality )
  • Ø Congenita B ( fractures in utero / birth with 8% mortality )
  • Ø Tarda A ( fractures before walking age )
  • Ø Tarda B ( fractures after walking age )


Extra skeletal tissues and organs affected by type 1 collagen defects

  • Ø Sclera
  • Ø Dentin
  • Ø Bone
  • Ø Ear
  • Ø Skin
  • Ø Heart valves
  • Ø Vessels
  • Ø Capillaries


The most common cause of spontaneous multiple fractures all over the body ,  without any history of trauma , in different stages of healing , mainly involving the long bones , is Osteogenesis Imperfecta provided there are no superficial marks of any violence e.g abrasion , laceration , incised wound etc. , else the most common cause becomes Battered baby syndrome / Caffey ‘s syndrome.



  1. sir kindly put all possible mcqs. of IO SO THIS topic would be clear here itself ! if possible for you ! thanks !

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