USMLE Step 1 Question of the Week #13

A 26-year-old man presents to ophthalmologist for complain of progressive loss of vision in his right eye for last six months. He has visited multiple doctors till date, but there is no improvement. There is no history of pain or redness in eyes. He often experiences fatigue for last one year. His detailed medical history reveals that he has suffered from fractures of different long bones two times; both the fractures were associated with minor injury. His detailed ophthalmologic evaluation suggests diagnosis of optic atrophy on right side. His recent complete blood counts revealed that his blood hemoglobin level was 9.2 g/dL (5.71 mmol/L). Considering a specific condition as a differential diagnosis, the ophthalmologist orders radiogram of his spine, which confirms the diagnosis. The radiogram is shown below:

Which of the following mechanisms best explains pathophysiology of the condition the man is suffering from?

A. Abnormal accumulation of mucopolysaccharides in chondrocytes

B. Decreased synthetic activity of osteoblasts

C. Primary oversecretion of parathyroid hormone

D. Defective acidification of osteoclast resorption pit

E. Defective assembly of collagen polypeptides.


QID #1838


USMLE Step 1 Question of the Week #12

A male newborn, delivered at full term, has abnormal facies and is suspected to have a chromosomal anomaly. Histological examination of his umbilical cord shows following findings:

Which of the following chromosomal anomalies is most commonly associated with above findings in umbilical cord?


A. Down syndrome

B. Edward syndrome

C. Klinefelter syndrome

D. Patau syndrome

E. Turner syndrome

QID #1023

USMLE Step 1 Question of the Week #12

A 60-year-old man presents to ophthalmologist with history of progressive decline in vision in his right eye for last six months. After complete ocular examination, the ophthalmologist confirms diagnosis of cataract in his right eye. Additionally, he also notes a congenital defect in his iris on both sides. Image of the iris defect in his left eye is shown below.

Failure of closure of choroid fissure during which week of gestation results in above defect?

A. Week 6

B. Week 7

C. Week 8

D. Week 10

E. Week 11

QID #1017