Biology, Genetics & Bone Healing MCQs

A 4-year-old child presents with bowing of the legs and a waddling gait. Radiographs show widening and cupping of the metaphyses, strongly resembling rickets. However, laboratory investigations reveal normal serum calcium, phosphorus, alkaline phosphatase, and vitamin D levels. What is the most likely diagnosis?

An infant with severe micromelic dwarfism and prominent eyes is found to have widespread irregular, cupped metaphyses on radiographs. Laboratory studies reveal profound hypercalcemia and hypophosphatemia, yet parathyroid hormone levels are undetectable. The defective receptor in this condition physiologically binds to which of the following ligands?

A 3-year-old girl is diagnosed with nutritional rickets due to bowed legs and cupped, widened metaphyses on radiographs. However, her condition does not improve despite 6 months of high-dose vitamin D therapy. Labs show perfectly normal calcium, phosphorus, alkaline phosphatase, and 25-OH vitamin D levels. What is the most likely diagnosis?

A neonate is diagnosed with Jansen metaphyseal chondrodysplasia. Laboratory studies reveal severe hypercalcemia and hypophosphatemia. The genetic mutation associated with this disorder leads to which of the following mechanisms?

A 5-year-old girl is referred for bilateral bowed legs and a waddling gait. Radiographs show widened, irregular metaphyses and coxa vara. Serum calcium, phosphorus, alkaline phosphatase, and 25(OH) vitamin D levels are strictly within normal limits. Based on the most likely diagnosis, how should her condition be initially managed?

A 10-year-old boy presents with progressive facial paralysis and hearing loss. Radiographs show mild metaphyseal flaring of the long bones and severe hyperostosis of the cranial vault and skull base. A mutation in the ANKH gene is identified. The primary mechanism of this disease involves defective:

A 7-year-old boy is diagnosed with pseudoachondroplasia after presenting with short-limbed dwarfism, a waddling gait, and joint laxity. His facial features are entirely normal. Radiographs show small, irregular epiphyses and widened metaphyses. The pathophysiology of this disease involves the intracellular accumulation of an abnormal protein within the rough endoplasmic reticulum. Which gene is mutated?

A 3-year-old boy presents with profound short stature, micrognathia, and hypercalcemia. Radiographs display wide, irregular, and markedly cupped metaphyses. Laboratory evaluation reveals hypophosphatemia and undetectable levels of endogenous parathyroid hormone (PTH). What is the exact pathophysiologic mechanism for his hypercalcemia?

A patient with systemic sclerosis presents with progressive shortening of her distal digits. Radiographs reveal resorption of the terminal phalangeal tufts. Which pathophysiology primarily drives this specific musculoskeletal manifestation?

A 55-year-old female with limited cutaneous systemic sclerosis presents with painful, firm subcutaneous nodules on her fingertips that occasionally extrude a chalky white material.

What is the initial recommended medical therapy to manage these symptomatic lesions?

A 12-year-old girl is diagnosed with a symptomatic, solitary eosinophilic granuloma of the proximal humerus confirmed by biopsy. Which of the following is the most appropriate minimally invasive treatment option that has demonstrated high rates of resolution?

When screening a diabetic patient for loss of protective sensation using the 5.07 Semmes-Weinstein monofilament, which of the following techniques is considered the standard of care?

During screening, a diabetic patient is found to have a localized area of thick callus with underlying ecchymosis on the plantar aspect of the first metatarsophalangeal joint. The skin is intact. How is this lesion classified under the Wagner Diabetic Foot Ulcer Classification System?

During a diabetic foot screening, the examiner uses a 10g Semmes-Weinstein monofilament. What is the proper technique for applying this device to ensure an accurate assessment of Loss of Protective Sensation (LOPS)?

When utilizing the 10-gram (5.07) Semmes-Weinstein monofilament to screen for loss of protective sensation, which of the following describes the correct application technique?

Histological examination of a lesion in a patient with Fibrous Dysplasia typically reveals which of the following features?

A 7-year-old child presents with a waddling gait, bilateral knee pain, and restricted joint mobility. Radiographs demonstrate delayed, irregular ossification of multiple epiphyses and a characteristic "double-layered" patella. A mutation in which gene is most commonly associated with this phenotype?

A 14-year-old male presents with delayed eruption of secondary teeth and the ability to easily approximate his shoulders anteriorly. Radiographs show delayed ossification of the cranial sutures and midline structures. Which gene is mutated in this condition?

An infant with malignant osteopetrosis presents with cranial nerve palsies, hepatosplenomegaly, and recurrent fractures. Radiographs show a "bone-in-bone" appearance. What is the primary cellular defect responsible for this condition?

A newborn presents with respiratory distress, severe anterolateral bowing of the femora and tibiae, and pretibial skin dimpling. Genetic testing reveals a mutation in SOX9. This condition is most closely associated with which of the following anomalies?