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From: louanne ellison <>
Subject: [CHS] Genetics and blood typing
Date: Fri, 18 Aug 2000 23:50:54 -0700


Hi,

For some reason I can't respond to people using their given email if they
are from England, so I'm sending this directly to the list.

Blood types are directly inherited and not influenced at all by environment.



Genetics was my favorite subject in college, but it was awhile ago. Gene
distribution hasn't changed though so here goes.

First, one carries two genes for the Rhesus portion of their blood type and
two for the A,B, and O portion.

Second Rhesus - means the Rhesus factor is not present. O type means the A
and B factors are not present. In other words, - and O means there are no
genes present for these typings.

Rhesus + is always dominant whether someone carries one or two. Therefore
Rhesus - is recessive and doesn't show unless someone is carrying two of
these non-Rhesus + genes.

A and B always show up when they are present because they are both equally
dominant. Therefore O only shows up when neither A or B are present.

Now when you are Rhesus-, O type you have no genes present for either
typing, Rhesus + or A/B factors.

What this also means is that both your parents were carrying a Rhesus - and
an O factor. Otherwise you would have had to have been one of the dominant
typings that they are, because each parent gave you one of their two genes
for each of these factors. O- is fairly rare because of this requirement
and the ability to have children with this typing can be hidden for
generations.

Information about the prevalency of various blood types per regions of the
earth should be available from Genetic Counseling sources at hospitals,
genetic data banks, etc.

Possible blood types: AA++, AA--, AA+-, AB++, AB--, AB+-, BB++, BB--, BB+-,
AO++, AO--, AO+-, BO++, BO--, BO+-, 00++, 00--, OO+-.

AO--, AO-+, BO--, BO+-, and OO--, OO+- are parental possibilities for a 00--
child otherwise known as Rhesus neg O type, or O negative type child.

Hope this helps.

Best wishes and regards
Louanne
in San Jose by the San Francisco Bay




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