Biology, Genetics & Bone Healing MCQs

A 12-year-old boy is diagnosed with Camurati-Engelmann disease based on classic radiographic findings of bilateral femoral diaphyseal thickening and a confirmed TGFB1 mutation. He reports severe, debilitating leg pain and progressive muscle weakness. Which of the following is the most effective medical therapy for his symptoms?

A newborn presents with micromelic shortening of the limbs, severe clubfeet, rigid "hitchhiker" thumbs, and cystic swelling of the pinnae. Radiographs show a first metacarpal that is short and oval-shaped. Which of the following is the defective cellular process in this dysplasia?

A 16-year-old male presents with knee pain. Radiographs reveal an eccentric, lytic lesion with a sclerotic margin in the proximal tibial metaphysis.

Which of the following is the hallmark histological feature of this lesion?

A 12-year-old girl with a known TGFB1 mutation presents with severe bilateral leg pain, muscle weakness, and a waddling gait.

Radiographs confirm progressive diaphyseal dysplasia (Camurati-Engelmann disease). Which pharmacological treatment is considered first-line to improve her symptoms and walking tolerance?

A 14-year-old boy presents for evaluation of frequent shoulder dislocations. Examination reveals he can touch his shoulders together in the midline. Dental examination shows delayed eruption of secondary teeth. The underlying mutation involves a transcription factor essential for which of the following cellular processes?

A 9-year-old child presents with severe leg pain, waddling gait, and profound muscle weakness. Radiographs demonstrate bilateral symmetric cortical thickening of the long bone diaphyses with sparing of the epiphyses and metaphyses.

Which of the following medications is considered first-line for relieving symptoms and improving strength in this condition?

A 24-year-old male presents with a dull ache in his proximal leg. Radiographs demonstrate an eccentric, sharply circumscribed lytic lesion in the proximal tibial metaphysis with a sclerotic margin.

Biopsy demonstrates a lobular arrangement of spindle or stellate cells in an abundant myxoid background, with osteoclast-like giant cells at the lobule periphery. What is the most appropriate definitive management for this lesion?

During fracture healing, intramembranous ossification occurs without a cartilage intermediate. Which of the following transcription factors is most essential for the differentiation of mesenchymal stem cells into osteoblasts during this process?

A 70-year-old female who has been taking alendronate for 12 years presents with an atraumatic, dull, aching pain in her right thigh. Radiographs demonstrate lateral cortical thickening and a transverse radiolucent line in the subtrochanteric region of the right femur. What is the most appropriate management?

A 30-year-old female presents with an expansile, lytic lesion in the distal radius. Biopsy confirms a giant cell tumor of bone. She is treated medically with denosumab prior to surgery. What is the specific target of this medication?

A diaphyseal tibial shaft fracture is treated with a rigid compression plate, achieving absolute stability and anatomic reduction. Which mechanism of bone healing will predominantly occur in this scenario?

Biopsy of a radiolucent, eccentrically located metaphyseal lesion in a 14-year-old female reveals blood-filled spaces lined by mononuclear cells and multinucleated giant cells, lacking true endothelial lining. Cytogenetic analysis is most likely to show an abnormality in which gene?

A 12-year-old boy with a history of recurrent fractures, hepatosplenomegaly, and anemia is diagnosed with osteopetrosis. The primary cellular defect in this condition is characterized by:

A newborn infant is noted to have very dense, thick bones on a skeletal survey, with a "bone-in-bone" appearance. The parents are informed the child may require a bone marrow transplant. What is the primary cellular defect in this condition?

A 7-year-old girl is evaluated for delayed dental eruption and abnormal shoulder mobility. Physical examination reveals the ability to approximate her shoulders anteriorly in the midline. Radiographs show absent clavicles and delayed closure of cranial sutures. Which transcription factor is primarily defective in this syndrome?

A 14-year-old female presents with an impending pathologic fracture of the proximal femur with a characteristic "shepherd's crook" deformity. Radiographs show a "ground-glass" medullary appearance. Which of the following represents the genetic etiology of her condition?

A 7-year-old child presents to the orthopedic clinic with extreme shoulder hypermobility, allowing the patient to touch the bilateral shoulders together anteriorly in the midline. The patient also has delayed closure of the cranial sutures. A mutation in which of the following genes is responsible?

An infant presents with recurrent fractures, cranial nerve palsies, and pancytopenia. Radiographs show a "bone-within-bone" appearance and generalized osteosclerosis. The infantile malignant form of this disease is most commonly due to a defect in which of the following?