Osteogenesis imperfecta

A 4-year-old girl is brought to the emergency department by her parent after a fall. The patient was running on the playground when she tripped and fell onto the mulch. She did not hit her head or lose consciousness. Past medical history is significant for several fractures that occured after minor trauma. Her parent also has a history of multiple fractures. The patient has been meeting most developmental goals but is experiencing language delays, for which she is scheduled to receive a hearing test in the upcoming week. The patient is at 15th and 20th percentile for height and weight, respectively. Vitals are within normal limits. Physical examination shows bruising along the left lateral thigh, knee, and elbow. Kyphoscoliosis is also noted. Examination of the patient’s oropharynx reveals the following finding:


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Laboratory results are within normal limits. Plain radiograph shows a fracture of the olecranon. Which of the following is the most likely explanation for the patient’s presentation?