Conference moira::parenting

This note is being entered for a member of our community who wishes to
remain anonymous.  

     Carol duBois, PARENTING co-moderator

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Hello,

If a woman wanted to have a child by her maternal grandmother's sister's son,
would there be any health issues to consider? 

I know if a father/daughter or mother/son have a child, there are 
consequences with genetics, (ie, possible retardation, physical handicaps, 
etc).

Researching before pursuing... 

Thanks in advance

    I am guessing that this is like a second cousin relationship?
    
    I would imagine risks would depend on the family history on the
    Grandmother's and Great Aunt's side of the family.  If there are
    significant genetic problems on that side of the family there would
    probably be an increased risk of children of this relationship
    inheriting those problems.  
    
    Meg

    Actually, this situation is first cousin, once removed.

I must admit to no training at all in genetics, BUT it seems to me
that 1/16 (one sixteenth) of the genetic material of the person
putting the question and her first cousin once removed is likely to be
in common.  For an autosomal recessive trait possessed by one of the
questioner's and her partner's common ancestors, this means that there
is a 6% chance for each of their offspring of inheriting two copies
(i.e. the defect), which is much more than it would be with totally
unrelated parents, but still pretty small. 

For an autosomal dominant trait, the chance of inheriting the defect
(one copy) is 3/8, on the assumption that the nearest common ancestor
(one of the questioner's relevant great-grandparents) possessed it. 
But a dominant trait is very likely to have been expressed somewhere
in the family, probably in a continuously inherited line, so if there
are no obvious genetic defects there should be no worry. 

    There are several genetic counseling centers you may contact
    in the Boston area. We were counseled by one in Lexington. I
    am a carrier of Trisomy 13 similar to Trisomy 21 (Downs Syndrome).
    Dr. Miller is the doctor in Lexington/Concord area. I think
    the name of the practic is Prenatal Dianostics.  Also, BU has
    a similar program/practice.  Some of the Biotech firms may also
    has counselors specializing in this area.
    
    Whoever you do contact will probably wish to perform a chromesome
    analysis on both you and the relative in question.  I recently
    found out that I most likely inherited this from my mother's side
    of the family.  One of my cousins on my mother's side had the 
    chromesome analysis done and this person is a carrier as well.
    
    The analysis is simple. They just draw some blood.  It may take
    several weeks for the results.  A counselor specializing in this
    field will discuss the outcome and statistics involved if anything
    is found. Finding out greatly helped us come to terms with alot
    of feelings and confusion and gave us a knowledge base for making some
    tough decisions.
    
    Good Luck
    
    -- Pat K.
    
    

I agree completely that genetic counseling can be
valuable in deciding such questions.  But, I am
also reminded of my sociology class from college.

The professor convinced me that restrictions on
marriage between relatives is not genetics driven
as much as we think.  I wish I could remember
exactly what was involved, but I *do* remember
he used hemophilia and Tay Sachs to prove that
cousins have little to no more probability of
having children born with the syndrome than
strangers.  It may have been 2nd cousins (that is,
my child mating with my sister's grandchild).

His point was that such restrictions are more
driven by family affiliations and wealth
distribution than by genetics.  Hence the
classic objection against a child's spousal choice
is against the family's social status, not their
medical history.

Just another little tidbit stored in my brain,
shoving out more important information, such as
where I put my car keys...

Pat

    My anthro teachers agreed: the concept of "incest" is a 
    way of making people marry outside their family and thus
    creating social bonds with a larger group of people than
    marrying inside the family would.  This is a long-term
    benefit: hard times are easier to survive as there are
    more people to help (and to diversity risk); when there's
    conflict between neighboring groups, there are likely to
    be family members (or their children) of one group in the
    other who are natural mediators between the two groups.
    
    But it's not what people want--they want the familiar and
    the local.  So you need a "big hammer" with lots of emotional
    force.
    
    The genetic argument has some force, but not enough to explain
    the fierce prohibitions most societies have.
    
    Or so I was told.
    
    	-John Bishop

    
                      mother  --  father
                            /   |
                           A1   B1
                           /    \
                           A2   B2
                           /    \
                           A3   B3
                           /    \
                           A4   B4
    
    parents have 2 children; A1 and B1. A2 is the child of A1, A3 is the 
    child of A2 (and etc with the B family line). For argument's sake,
    the A's are women and the B's are men.
    
    
    A1 and B1 are siblings              
    A2 and B2 are 1st cousins           
    A3 and B3 are 2nd cousins
    A4 and B4 are 3rd cousins
    
    A1 and B2 are aunt and nephew 
    A1 and B3 are great aunt and great nephew
    
    A2 and B3 are 1st cousins once removed
    A2 and B4 are 1st cousins twice removed
    
    A3 and B4 are 2nd cousins once removed
    
    
    BTW, I'll agree with the social aspects, since marrying outside the 
    immediate family was recommended long before genetics. However,
    there are a lot of instances were close marriages WERE (and still
    are) the norm to keep within certain social circles (royal families)
    with sometimes very obvious genetic consequences. This was usually
    the case with constant intermarriage though, and not usually the 
    case with isolated incidences.
    
    Monica

>>    A1 and B3 are great aunt and great nephew


grand aunt and grand nephew....as in sister or brother of grand mother or grand
father.

great aunt is sister of great grand mother or great grand father.

michael

    I think we only have a difference in label here - I have always 
    read that my aunt is my daughter's GREAT aunt. NOT grand aunt.
    Although, your way DOES make more sense, I have never heard it used....
    
    Monica

but I heard the terms used by a geneologist one time, and it made so much sense
that it has stuck in my mind ever since.

michael

I use a combination of both. I call my niece's daughter my grand-niece,
and say that I am a great-aunt as I had never heard of grand-aunt before.
I sure do get some strange looks, though, when I say I'm a great-aunt as
people picture someone who is a grandmother or great-aunt to be old, and
I became a great-aunt when I was 26, so I don't fit the stereotype.  But
then, there are only a few years bewteen me and my niece.

Cathy

This note is being entered by a member of our community who wishes to
remain anonymous.

   Carol duBois, PARENTING co-moderator

******************************************************

	Regarding the original question, I believe the risks in your case
would be nil.

	My spouse and I are first cousins.  (Yes, it's legal in about 50%
of the states in the union.)  When we decided to have a baby, we went for
genetic counselling at UMass.  The doctor basically had us give a family
medical history, looking for genetically linked disorders.  There weren't any
evident in the history we were able to give. 

	He didn't bother with any special chromosome tests or anything.
After looking at our info, he told us that our odds of having a problem were
only slightly higher than the general population's, and went so far as to
say that an amnio would not be called for during the pregnancy unless other
circumstances warranted it.  With that reassurance, we went ahead with becoming
pregnant. 

	During the pregnancy, we wanted to put all the odds in the baby's
favor that we could.  Not only because it was generally the right thing to
do, but also because if anything went wrong, people would say that it was
because of our relation.  So no drinking, no visiting smokers or smoky places,
outrageously healthy eating (the guidelines in "What to Expect..." can drive
you nuts), and so on.  Our reward was a rather large birth-weight, extremely 
healthy and beautiful baby.

	Ours is anecdotal evidence, with the caveats that apply.  However,
I think the opinion of the doctor (which amounted to "no big deal") and the
other replies to this note should tell you it's definitely okay in your case.
Get the genetic counselling for peace of mind, and go ahead.

	signed,

	Been_there


P.S.  This is anonymous because society can be a bit brutal on this subject.
You're "allowed" to slam this sort of relationship as deviant and not look
like a bigot or an ignoramous in the process, i.e., sitcoms that refer to 
"cousin-lovin' hillbillies."  ("Grace Under Fire" pops to mind.)  Still
I'd rather not be granted shelter under the "politically correct" umbrella;
we just grin and bear it.  Another caveat for the noter in .1 to consider.

    I remember I've seen in this conference a long time ago the information 
    on the probability of the Trisomy 21 growing with the womans age. Now I
    don't seem to be able to find it. Can someone please refer me to the
    right note?
    
    
    Thanks.
    

    re: .14
    
    There is some discussion about the risks of Trisomy 21 (Down Syndrome)
    in note 82 "CVS, AFP, MSS, Amnio - Prenatal Testing " - particularly
    82.11 has some data on the risks at particular ages. 
    
    Carol Stolicny, PARENTING co-mod

    Anonymous reply from the author of 669.1.

         Carol duBois, PARENTING co-moderator

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As base noter of this topic, I would like to thank all of you for your 
replies. It makes me feel better knowing that the risk appears to be
minimal. 

We WILL, of course, consult with our doctor before seriously pursuing
having a child.

Thanks again!