Biology, Genetics & Bone Healing MCQs

A 5-year-old boy presents with progressive bowing of his legs and short stature. His mother has a similar history and required bilateral corrective osteotomies as a teenager. Genetic testing confirms a PHEX mutation. Which of the following is the hallmark of the indicated medical treatment?

A 14-year-old female presents for evaluation of shoulder hypermobility. She can easily approximate her shoulders anteriorly in the midline. Examination reveals delayed eruption of permanent teeth. What is the genetic inheritance pattern and associated gene mutation for this condition?

A 6-year-old boy with X-linked hypophosphatemia (XLH) continues to have progressive lower extremity bowing despite standard oral phosphate and calcitriol therapy. Which of the following targeted therapies directly addresses the underlying pathophysiology?

A 45-year-old female presents with diffuse bone pain. Radiographs demonstrate bilateral pseudofractures of the medial femoral neck.

If an iliac crest bone biopsy with double tetracycline labeling is performed, what is the expected histologic finding?

Which of the following statements most accurately distinguishes the underlying pathophysiology of osteomalacia from that of osteoporosis?

A 4-year-old boy presents with progressive bowing of the lower extremities. Labs show normal serum calcium, low serum phosphate, and elevated alkaline phosphatase. Genetic testing reveals a mutation in the PHEX gene. Which of the following is the primary mechanism of this disease?

A 45-year-old female with a history of systemic sclerosis presents with progressive shortening of her distal fingers and painful, chalky subcutaneous nodules on her fingertips. Radiographs reveal resorption of the terminal phalangeal tufts. What is the most appropriate initial management for the subcutaneous nodules if they become acutely inflamed but lack signs of systemic infection?

A 5-year-old boy presents with progressive bowing of the legs and short stature. Labs show normal serum calcium, markedly low serum phosphate, and elevated alkaline phosphatase. Genetic testing reveals a mutation in the PHEX gene. Which of the following best explains the pathophysiology of his condition?

A 45-year-old strict vegan presents with generalized bone pain and a waddling gait. Radiographs show transverse radiolucent bands in the femoral neck and pubic rami. If a bone biopsy were performed following double tetracycline labeling, what would be the expected finding?

A 60-year-old female with a history of celiac disease presents with generalized bone pain and proximal muscle weakness. Her radiographs demonstrate pseudofractures.

Which of the following laboratory profiles is most consistent with her diagnosis?

A 48-year-old woman presents with generalized bone pain and muscle weakness. Radiographs reveal bilateral radiolucent bands perpendicular to the cortex in her femoral necks.

Histological analysis of these bands would most likely demonstrate an accumulation of which of the following?

A 35-year-old patient on long-term phenytoin therapy develops osteomalacia. Which of the following best explains the mechanism of antiepileptic-induced bone disease?

A 5-year-old boy presents with short-trunk dwarfism, a waddling gait, myopia, and a history of cleft palate. Radiographs show delayed ossification of the femoral heads and severe coxa vara. He is diagnosed with spondyloepiphyseal dysplasia (SED) congenita. This disorder is caused by a mutation affecting which of the following proteins?

A 5-year-old girl is diagnosed with X-linked hypophosphatemic rickets (PHEX mutation). Which of the following is the gold standard medical therapy to prevent progression of skeletal deformity?

A 2-year-old boy with a history of anterolateral tibial bowing develops a pseudoarthrosis after a minor fall. He has multiple cafe-au-lait spots. The underlying genetic mutation affects a protein primarily involved in which of the following cellular pathways?

A 17-year-old male presents with chronic neck pain. Radiographs demonstrate an expansile lesion in the posterior elements of C4.

Histologically, the lesion consists of woven bone trabeculae lined by prominent osteoblasts. Which of the following strongly differentiates this lesion from an osteoid osteoma?

A 10-year-old girl is evaluated for a broad skull, delayed fontanelle closure, and the unusual ability to touch her shoulders together anteriorly. Which gene mutation is responsible for her condition?

A 10-year-old girl is evaluated for short stature and delayed primary tooth eruption. On examination, she is able to bring her shoulders together anteriorly. Radiographs reveal absent clavicles and delayed skull ossification. Which transcription factor is mutated in this condition?

A 10-year-old boy is brought in for an abnormal shoulder appearance. He has excessive shoulder mobility and can touch his shoulders together anteriorly. Radiographs show complete absence of the clavicles. Which gene is primarily mutated in this condition?