作者c20001222 (机哥)
看板medstudent
标题[申覆] 医学二 97
时间Tue Feb 22 21:59:08 2011
[申覆] 医学二 (97)
答案为A 申覆：AC 或 送分
出处：Robbins and Cotran Pathology Basis of Disease 8th edition p.287
In familial cases, children inherit one defective copy of the RB gene in the
germ line(one hit); the other copy is normal. Retinoblastoma develops when
the normal RB allel is mutated in retinoblasts as a result of spontaneous
somatic mutation(second hit). Because only a single somatic mutation is
required for loss of RB function in retinoblastoma families, familial
retinoblastoma is inherited as an autosomal dominant trait.
答案A：『由Rb 基因的单点突变所引起』，推测考试重点为"two hits theory"，
然因无英文以供中英对照，
故"单点突变"、"点突变"、"单一点突变"之间，或有语意上混淆之嫌，
如选项改为类似『由Rb 基因唯一一个位置上的点突变所引起』等叙述法，
则或许较无题意模糊之疑虑。
且於familial cases中，其两个异常alleles，一者为遗传(one hit)，
一者为後天突变(second hit)，亦即先天有突变之allel只有其中一个位置，
也可作为答案A可行之佐证。
因上述原故，答案建议改为 送分 。
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※ 编辑: c20001222 来自: 61.231.26.40 (02/22 22:00)
1F：推 Aramis:我觉得好像可以喔，因为後面写着: "...they lose the intac 02/22 22:33
2F：→ Aramis:t copy in the retinoblast through some form of somatic 02/22 22:34
3F：→ Aramis:mutation(point mutation, interstitial deletion of 13q14 02/22 22:35
4F：→ Aramis:or ever complete loss of normal chromosome 13). 02/22 22:35