Osteogenesis Imperfecta Flashcards
heterogenity
> 1 gene, similar phenotype
pleiotrophy
many effects, 1 gene
OI is
heterogenous heritable disorder of bone matrix formation and homeostasis
genetics of OI
types 1-6 are autosomal dominant, type 7 auto recessive
severity of OI
variable
type 2 is lethal
cardinal features of all OI
decrease in bone mass, decrease in bone mineral strength
increase in bone fragility, increase in bone deformity
characteristics of OI-1
normal stature with little to no deformity
blue sclera, hearing loss
hypermotility of jj and increase bruising of thin skin
aortic root dilation and mitral valve prolapse**
healing in O1
heal normally with normal callus formation
OI1 rarely affects
ribs, hands, feet
OI1 trajectory
rare during pregnancy and infancy, starts during childhood with walking and decreases after puberty then increases again with old age
OI1a vs OI1b
normal teeth vs dentinogenesis
OI2
minimal calvarial mineralization, beaded ribs, compression femurs and makred long bone derformity
(rib deformities–>lung hypoplasia–>death)
**perinatal lethal
OI3
progressive deformity
hallmarks of OI3
very short stature, perfectly healthy aside from boen deformity
progressively deforming bones–short curved bones with osteoporisis and an accordione ffect
other issues with OI3
scleral hue varies, hearing loss common, dentinogenesis
when do you know you have OI3
first few days
lethality in OI3
middle age
OI4 is
a cross between 1 and 3
type 1 collagen in OI
fibrillar collagen
fibrillar collagen formaton
trimer of two a1 and one a 2 monomer
genes for fibrillar collagen
expressed by COL1A1 on 17q and COL1A2 on 7q genes respectively
rare AR cases of OI have..
normal COL1A1 and COL1A2 genes (therefore normal pro-collagen) but abnormal post-translational modification (type 5-7)
tx options of OI
rehab
surgical rod placement
experiemental drugs in type 4
