A 5-year-old boy is brought to the pediatric clinic by his parents due to recurrent fractures over the past two years. They report that he has sustained fractures in his forearm and femur with minimal trauma, such as tripping while walking or falling from a low height. The parents also note that he has had delayed milestones in walking. The family history reveals that the father had frequent fractures as a child but improved with age. On physical examination, the child has short stature and bowing of the legs. His teeth appear discolored and brittle, suggestive of dentinogenesis imperfecta. Radiographs show osteopenia, multiple healed fractures, and mild deformities of the long bones. Genetic testing is performed and confirms a mutation in the COL1A1 gene. Which of the following findings is most characteristic of this disorder?
