A 45-year-old male with a history of osteoporosis is found to have low bone density on a DEXA scan. Laboratory tests show normal calcium and phosphate levels.  What is the most likely explanation for his low bone density? 

What is the significance of increased sporadic DNA mutations in older adults? 

A 30-year-old male athlete experiences increased bone density in his lower limbs after a period of intense training.  Which cells are primarily responsible for this adaptive response? 

What is the first step in the degeneration process of herniated disc disease? 

A 40-year-old male is diagnosed with Li-Fraumeni syndrome, a hereditary cancer syndrome associated with mutations in the TP53 gene.  What is the primary function of the TP53 gene in normal cells? 

A 7-year-old girl presents with headaches, vomiting, and difficulty walking. MRI reveals a mass in the posterior fossa.  What is the most likely diagnosis? 

A 65-year-old male with a history of rheumatoid arthritis presents with fatigue and joint pain. Laboratory tests show a hemoglobin level of 11 g/dL, MCV of 85 fL, and elevated inflammatory markers.  What is the most likely cause of his anemia? 

What is a common degenerative disease that affects the knee joint? 

What is the primary structural difference between hemoglobin A and hemoglobin S? 

A 22-year-old female basketball player presents with knee pain and swelling after landing awkwardly from a jump. She reports hearing a “pop” at the time of injury. Physical examination reveals a positive Lachman test.  What is the most likely diagnosis?