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drspleen - 03-14-11 23:29
A 2-month-old newborn male is brought to you by his parents, who report that 3 days ago he developed severe sunburn after only 90 minutes of sun exposure. Both parents are healthy. On examination, you note the child is very pale, except for the sun-exposed areas which remain erythematous and tender. If a genetic defect is responsible for these clinical findings, which will accumulate in this patient?
# A. Multiple double-strand breaks in the patient’s chromosomes
# B. Bulky distortions of the patient’s DNA
# C. Frameshift mutations
# D. Multiple single-strand nicks in the patient’s DNA
# E. G-T pairings
drspleen - 03-14-11 23:29
A 2-month-old newborn male is brought to you by his parents, who report that 3 days ago he developed severe sunburn after only 90 minutes of sun exposure. Both parents are healthy. On examination, you note the child is very pale, except for the sun-exposed areas which remain erythematous and tender. If a genetic defect is responsible for these clinical findings, which will accumulate in this patient?
# A. Multiple double-strand breaks in the patient’s chromosomes
# B. Bulky distortions of the patient’s DNA
# C. Frameshift mutations
# D. Multiple single-strand nicks in the patient’s DNA
# E. G-T pairings
The correct answer and explanation will be available after you answer.
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Re: 1 babbu5508 - 03-19-11 14:36 My answer is: b.
B. Bulky distortions of the patient’s DNA due to the pyrimidine dimers which form in patients with xeroderma pigmentosum..
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Re: 1 sudha2015 - 03-21-11 00:52 My answer is: b.
. Both parents are healthy. On examination, you note the child is very pale, except for the sun-exposed areas which remain erythematous and tender. If a genetic defect is responsible for these clinical findings
#4
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drspleen - 03-22-11 07:33 In XP, nucleotide excision repair mechanisms are absent, leading to accumulation of thymine dimers that are generated by UV damage. These dimers are bulky and cause distortions in the DNA. Patients are at 1000-fold increased risk for developing melanoma and squamous cell carcinoma of the skin.
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