发信人: yuffie (天天想你), 信区: Biology
标 题: Re: [转载] 求教：表兄妹结婚，后果真的很严重吗？
发信站: The unknown SPACE (Sat Apr 29 20:20:16 2000) WWW-POST

To make this more clear, I think my caculation won't differ
a lot
from the real world. Although, if we are talking a
perticular
disease, the danger is indeed not very high. Considering
there are
hundreds of locus for deadly genetic defect, another maybe
hundreds of
locus can increase your danger for cancer, heart attack, or
other
common diseases (which is not 100% controlled genetically).
It is
safe to say, first degree cousin marriage will sure give you
at
least one of the defect within those locus, whereas common
marriage
will only have very little danger to get you one. You may
argue that
the child born seems to be normal, if you are lucky enough
to avoid
those deadly locus. The thing you do not know is he/she
might be
100 or 1000 times easier to develop lung cancer, or some
other
diseases only occur after adulthood.
In genetics, it is called lost of heterogeneity by
inbreeding.
I strongly suggest that everyone should consider this before
making
that kind of marriage, unless you surely believe that you
are a lucky
person.

But in another words, inbreeding will be good for genetics
study. It
is very good to have a pedigree with indreeding when analyze
human
disease. It becomes harder and harder nowadays, because
less inbreeding.
:)



【 在 aquestion (aquestion) 的大作中提到: 】
: 【 在 yuffie (天天想你) 的大作中提到: 】
: : 几率大了很多。
: : 因为每个人都携带几十个隐性致病基因，正常情况，父母携带相同的
: : 隐性致病基因的概率很小。
: : 但是，表兄妹这种情况严重的多。
: : 假设每人携带20个隐性致病基因，兄妹之间将共享（Share）大约10
: : 个，
: : 表兄妹，是1/2*1/2*10＝2.5个。每一个隐性共享致病基因，后代患
: : 病
: : 的概率是1/4。2.5个，将是大约1-(3/4)^2.5＝51%。比较一般的遗传
: : 病
: : 的发病几率，大了1000倍左右。
:
: Are you sure your calculation is correct? Since I read
: following article from
: internet. Thanks a lot for your help.
: **************************************
: I'm married to my first cousin. We just hopped across
: the border to
: New York as Ohio has one of those nasty marriage laws. Have
: been in love with
: him all
: my life. We have a son who is perfect. The birth defect
: scare is a crock unless
: there
: have been multiple generations of close intermarriage (we
: are after all members of
: the
: animal kingdom). The genetic center we went to told us that
: the defect rate was
: only 2%
: & they were utterly unconcerned that we were first cousins!
: We were very
: surprised by
: their attitude because social propaganda had us believing
: all the lies. They were
: much
: more concerned about my age (38) & Downs than any problem
: related to our
: consanguinity. Which goes to show you that most of the
: material one reads about
: cousin
: marriages is nonsense. We've been together for six years and
: our family has
: always
: been very supportive. ...
:
:

--
人的发展史，就是生物系学生的一部血泪史。
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