Biology, Genetics & Bone Healing MCQs

A 35-year-old woman presents with chronic, deep aching pain in her right lower extremity and decreased range of motion in her knee. Radiographs reveal dense, irregular, eccentric hyperostosis along the cortex of the femur and tibia, resembling 'dripping candle wax'. Which of the following is the most likely diagnosis?

A 5-year-old child presents with a "hitchhiker" thumb, bilateral rigid clubfeet, and cauliflower ears. Radiographs reveal short, thick tubular bones. Which of the following genes is most likely mutated in this patient?

A 3-year-old is being evaluated for short stature, frontal bossing, and delayed closure of cranial sutures. The clavicles are completely absent on chest radiographs. Which transcription factor is primarily affected in this disorder?

A neonate presents with multiple fractures, blue sclerae, and profound osteopenia. The parents are carriers of a severe recessive form of this disease. Which of the following best describes the fundamental defect in the most common dominant forms of this condition?

A 4-year-old boy presents with knock-knees and short stature. Labs show normal serum calcium, normal phosphorus, normal alkaline phosphatase, and normal vitamin D levels. Radiographs show coxa vara, bowing of the femurs, and flared, irregular metaphyses. What is the most likely diagnosis?

A newborn is diagnosed with an autosomal recessive condition characterized by severe osteopetrosis, recurrent infections, and cranial nerve palsies. The underlying genetic defect most likely disrupts which of the following cellular components?

An 18-month-old girl presents with short stature, severe hypercalcemia, and hypophosphatemia. Radiographs show widespread metaphyseal cupping and fraying with striking osteopenia. Genetic testing reveals a mutation in the PTHR1 gene. What is the diagnosis?

A newborn presents with micromelic severe short stature, rigid equinovarus foot deformities, and bilaterally abducted "hitchhiker" thumbs. Physical examination also reveals cystic swelling of the external ear. What is the underlying genetic defect in this condition?

A 10-year-old boy presents to the orthopedic clinic with a wide waddling gait and the unusual ability to appose his shoulders anteriorly across his chest. Radiographs show widening of the symphysis pubis and coxa vara. Which transcription factor is primarily mutated in this syndrome?

An infant presents with failure to thrive, hepatosplenomegaly, and severe anemia. Radiographs demonstrate diffusely dense bones with a "bone-within-a-bone" appearance and loss of medullary canals. Which of the following represents the primary cellular mechanism defective in this severe condition?

A newborn presents with severe respiratory distress, shortened and anteriorly bowed lower extremities, and skin dimpling over the tibial bows. Karyotype analysis reveals a 46,XY genotype, but the external genitalia appear female. A mutation in which of the following genes is the definitive cause?

A 10-year-old boy with blue sclerae, dentinogenesis imperfecta, and multiple prior fractures is scheduled for rodding of his tibiae. His condition is caused by a dominant mutation in COL1A1. Which of the following best describes the fundamental defect in his bone collagen?

A 4-year-old boy presents with short stature, waddling gait, and progressive bowing of the lower extremities. Laboratory studies demonstrate normal calcium, phosphorus, and alkaline phosphatase levels. Radiographs show coxa vara and flared, irregular metaphyses, but the epiphyses are normal. A defect in which collagen type is most likely responsible?

A 5-year-old child presents with recurrent fractures, severe anemia, and hepatosplenomegaly. Radiographs exhibit a generalized increased bone density with a classic "bone-within-bone" appearance. What is the primary cellular defect responsible for this condition?

A 10-year-old boy presents to the orthopedic clinic with the ability to touch his shoulders together anteriorly across his chest. Examination reveals delayed closure of the fontanelles and multiple supernumerary teeth. Which transcription factor is mutated in this condition?

A newborn with phenotypic female genitalia is found to have a 46,XY karyotype. The infant exhibits marked anterolateral bowing of the tibiae and femora, hypoplastic scapulae, and severe respiratory distress. A mutation in which gene is responsible for this condition?

A 4-year-old child presents with short stature, severe bowing of the legs, and a waddling gait. Radiographs demonstrate flaring and irregularity of the metaphyses with widened physes mimicking rickets, but serum calcium and phosphorus are normal. Mutation in the gene encoding which collagen type is responsible?

A 12-year-old girl presents with a chronic limp and mild thigh pain. Radiographs reveal a ground-glass expansile lesion in the proximal femur with a characteristic shepherd's crook deformity. What is the underlying molecular pathogenesis of this condition?

The neurovascular theory of Charcot arthropathy suggests that autonomic neuropathy leads to which of the following physiological changes?

Fibrous dysplasia is caused by a somatic activating mutation in which of the following genes?