Biology, Genetics & Bone Healing MCQs

A patient with spondyloepiphyseal dysplasia (SED) congenita has widespread epiphyseal involvement and spinal abnormalities. The genetic defect responsible for this condition predominantly affects which of the following collagens?

A 2-year-old presents with bowing of the lower extremities and delayed walking. Radiographs demonstrate metaphyseal flaring and lucency mimicking rickets. However, laboratory evaluation reveals normal serum calcium, normal phosphorus, and normal vitamin D levels, but notably low serum alkaline phosphatase. What is the most likely diagnosis?

A 12-year-old girl is evaluated for delayed dental eruption and abnormal shoulder mobility. Physical exam reveals she can bring her shoulders together anteriorly. Radiographs show absent clavicles and delayed ossification of the pubic symphysis. Which transcription factor is mutated in this patient?

A 22-year-old female presents with severe back pain and neurological deficits. Imaging reveals a large, expansile, aneurysmal bone cyst in the sacrum that is deemed surgically unresectable. Which of the following medical therapies targets the RANKL pathway and is most appropriate for this lesion?

A neonate presents with severe bowing of the tibias, respiratory distress due to tracheomalacia, and a 46,XY karyotype but female external genitalia. This condition is associated with a mutation in which of the following?

A 9-year-old girl is able to bring her shoulders together anteriorly in the midline. She has delayed eruption of her secondary teeth. Radiographs demonstrate absent clavicles and a widened symphysis pubis. Which transcription factor is mutated in this disorder?

A 4-year-old boy with recurrent fragility fractures, blue sclerae, and dentinogenesis imperfecta is treated with cyclic intravenous pamidronate. What is the expected and characteristic radiographic finding on long bone X-rays following multiple cycles of this therapy?

A 68-year-old male presents with generalized fatigue, worsening back pain, and a recent humeral shaft fracture after a minor fall. Radiographs demonstrate multiple punched-out lytic lesions.

Which of the following factors is primarily responsible for the suppression of osteoblastic activity in this patient's disease process?

Which of the following describes the earliest biochemical change occurring in the articular cartilage during the pathogenesis of osteoarthritis?

A 35-year-old male undergoes curettage and cementation of a giant cell tumor of the distal femur. Six months later, he develops a massive recurrence that is deemed unresectable. Medical therapy with denosumab is initiated. What is the mechanism of action of this medication?

A 10-month-old infant is evaluated for short stature, frontal bossing, and a waddling gait. Radiographs reveal widening of the physes, cupping of the metaphyses, and bowing of the long bones. Laboratory studies show normal calcium, low phosphorus, and elevated alkaline phosphatase. Which of the following describes the underlying histologic defect?

A 30-year-old female presents with distal femur pain. Imaging reveals an eccentric, lytic, epiphyseal-metaphyseal lesion extending to the subchondral bone. Biopsy confirms Giant Cell Tumor (GCT). If medical therapy is considered, what is the mechanism of action of Denosumab?

A 70-year-old man presents with progressive hearing loss and increasing hat size. Radiographs demonstrate thickened cortices and coarsened trabeculae in the skull and pelvis. Paget's disease is diagnosed. The mixed phase of this disease is characterized by which of the following cellular activities?

In the pathophysiology of multiple myeloma bone disease, which cytokine pathway is primarily responsible for the uncoupled osteoclast activation leading to the characteristic lytic lesions?

What is the first-line medical treatment for managing severe bone pain and improving clinical symptoms in patients with Camurati-Engelmann disease (progressive diaphyseal dysplasia)?

A 65-year-old male presents with severe mechanical back pain. A skeletal survey demonstrates multiple punched-out lytic lesions in the skull and spine.

Which of the following molecules, secreted by the malignant cells in this condition, is primarily responsible for the uncoupling of bone remodeling by directly inhibiting osteoblast differentiation?

A 28-year-old female presents with knee pain. Radiographs show an eccentric, lytic epiphyseal lesion in the distal femur. Biopsy reveals multinucleated giant cells interspersed among mononuclear spindle cells. She is prescribed denosumab. What is the precise cellular target and mechanism of this medication in her condition?

A 22-year-old female undergoes corrective osteotomy for a 'shepherd's crook' deformity of the proximal femur. Pathology demonstrates a stroma of bland spindle cells with irregularly shaped trabeculae of woven bone lacking osteoblastic rimming. This condition is caused by a somatic activating mutation in which gene?

A newborn is noted to have a large anterior fontanelle, delayed closure of cranial sutures, and hypermobility of the shoulders, allowing them to be approximated in the anterior midline. Radiographs reveal hypoplastic clavicles. This condition is caused by a mutation in a gene essential for the differentiation of which cell type?

A 32-year-old female presents with knee pain. Radiographs show an eccentric, purely lytic lesion in the distal femur epiphysis extending to the subchondral bone. A biopsy reveals multinucleated giant cells. Which of the following targeted therapies is most appropriate for unresectable disease?