245. Inherited C.T. Disorders Flashcards
How are children Xrays different?
- Cartilage precursors of bone not mineralized = not visible
- Growth plate radiolucent until growth ceases
- Epiphysis lucent (dark), mineralizing at predictable times during childhood/adolescence
Good to compare bone age to chronological age
Achondroplasia
Type, Sx, Imaging
Metaphyseal Dysplasia
Most common cause of dwarphism
Shortening of proximal limbs, trident hand, macrocephaly, kyphosis, cor pulmonale (RV problems), apnea, normal intelligence
Pelvis: horizontal acetabular roof “paddle w/o handle”
Vertebrae: distance b/w pedicles decreases down spine
Abnormally long fibula
Genetics of Achondroplasia (Pathophysiology, possible tx)
AD inheritance/de novo (more likely in older fathers) Mutated FGFR3 (Gly380Arg) = constitutively active = always inhibits chondrocyte proliferation in zone of hypertrophy
CNP analoge - binds NPR-B = could inhibit FGF as possible tx
Osteogenesis Imperfecta (type, genetics, sx, tx)
Metaphyseal Dysplasia (brittle bone disease)
Abnormal type 1 collaged
AD - haploinsufficiency/dominant negative
Wide rande of severity - fractures with minimal trauma, blue sclera, “wormian” islands bones of skull
Tx: bisphosphonates: harden bone
Ehlers-Danlos Syndrome
type, genetics, sx
Collagenopathy - Type V collagen defect
Soft, velvety skin - hyperelastic/fragile - easy to tear/bruise
Joint hypermobility, dislocations
MV prolapse, hiatal hernia, anal prolapse, flat feet
Genetics: mutation in COL5A1/2 = null allele (AD)
Marfan Syndrome
Pathophysiology, Genetics
AD, 30% de novo
Fibrillin 1: forms microfibrils as scaffold for elastic fiber formation and bind TGF B
Defect in fibrillin: problem with elastic tissue and TGF B released in excess
Marfan Syndrome Sx
Scoiliosis, Arachnodactyly, Joint Laxity, Ocular Abnormalities (Myopia) CV Disease (MV Prolapse, Aortic root dilation, dissection, aneurysm) Pts are long, lean, long limbs, sternum abnormality Flat feet, +thumb-and-wrist sign