Congenital and metabolic bone disorders Flashcards
Inheritance of achondroplasia
Autosomal dominant
Mutation in achondroplasia
FGFR3 on chromosome 4, inhibits endochondral growth
Narrow and disorganizes zones of proliferation and hypertrophy of bone
Achondroplasia
Laron dwarfism
Pituitary dysfunction or secondary to a mutation in growth hormone receptor
Inheritance of osteogenesis imperfecta
Autosomal dominant
Deficiencies in type I collagen synthesis related to defects in EC structural proteins
Osteogenesis imperfecta
Mutation in osteogenesis imperfecta
COL1A1 and COL1A2 genes encoding alpha-1 and -2 chains of type 1 collagen due to replacement of glycine
Group of rare genetic disorders characterized by reduced bone resorption due to deficient osteoclast development or function
Osteopetrosis
Mutations and inheritance associated with osteopetrosis
TCIRG1 –> AR
CLCN7 –> AD
CA-II –> AR
Normal function of TCIRG1
Makes an osteoclast proton pump
Normal function of CLCN7
Osteoclast chloride channel
Albers-Schonberg disease
Osteopetrosis caused by CLCN7 mutation
Normal function of CA-II
Generates protons and facilitates the resorption pit acidification by osteoclasts
Deposited bone tends to woven instead of lamellar
Osteopetrosis
Inheritance of infantile osteopetrosis
Autosomal recessive