A 21-year-old man visits his opthamologist because of a sudden loss of vision in his left eye.
He was playing golf with his father two days ago when he noticed his left vision was blurry.
The next morning, vision in his left eye was completely lost. He says that both his mother and
grandmother lost their vision one eye after the other. Fundoscopic examination of the left eye
reveals enlarged peripapillary vessels. There is no pupillary response in the left eye. Direct
pupillary constriction in the right eye is slow. A family pedigree of the patient (IV-4) is shown.
What term best explains why I-2 and II-3 are not affected?
- A. Pleiotropy
- B. Allelic heterogeneity
- C. Locus heterogeneity
- D. X inactivation (lyonization)
- E. Heteroplasmy
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A 19-year-old man visits his physician with a deep 5 cm (2 in.) laceration on the mid-posterior
region of his right arm. He was involved in a gang fight 30 minutes ago. The wound bleeds
profusely. Physical examination reveals he cannot extend his right arm at the elbow or
extend his right hand at the wrist. An X-ray of the humerus shows no fractures. If left
untreated, what is the likely fate of his limb in the pursuing months?
- A. Infarction due to vessel coagulation
- B. Infarction due to fat embolism
- C. Permanent paralysis due to nerve death
- D. Permanent paralysis due to wallerian degeneration
- E. Full recovery with scar formation
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A seven-year-old girl was brought to the physician by her father because of abnormal
behavior. Yesterday morning she was complaining of a headache. By the evening she
complained of hearing voices and refused to eat or drink. She has not slept in 48 hours.
Physical examination shows two sets of scars on the right forearm that resemble bite marks.
The most likely causative agent entered the cerebrum through which transport molecule?
- A. Dynein
- B. Kinesin
- C. Albumin
- D. Transferrin
- E. Hemoglobin
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