A 22-year-old man has recurrent low-trauma fractures, short stature, persistently open cranial sutures, hypoplastic clavicles and resorption of the di...

Question

A 22-year-old man has recurrent low-trauma fractures, short stature, persistently open cranial sutures, hypoplastic clavicles and resorption of the distal phalanges. Bone density is diffusely increased. Which cellular defect best explains this phenotype?

Accepted Answer

Impaired osteoclast collagen degradation because of cathepsin K deficiency

Answer

Failure of osteoblast WNT signalling because of LRP5 deficiency

Answer

Defective acidification of the osteoclast resorption lacuna from TCIRG1 deficiency

Answer

Constitutive TGF-beta signalling within diaphyseal osteoblasts

Answer

Failure of type I collagen N-terminal processing

Atrial Fibrillation — MRCP Part 1 MCQ

A 22-year-old man has recurrent low-trauma fractures, short stature, persistently open cranial sutures, hypoplastic clavicles and resorption of the distal phalanges. Bone density is diffusely increased. Which cellular defect best explains this phenotype?