kris@maui.WV.TEK.COM (Kristen McCormick) (08/16/89)
I'm posting here because I didn't know who else to ask. I am probably the only person on earth who never had biology in high school, or anywhere else (I may take it next term though). So my question is, are blood types inherited? Can a father with type A positive blood and a mother with AB negative (I think) have a child with O positive blood? If it helps any, the other child has A positive. My husband and I both have O positive, and so does our daughter, so I'm assuming heredety has something to do with it. But is it always? Is it like, absolute, or are there dominant and recessive like eye color? Anyone? Thanks. kris Kristen McCormick kris@maui.wv.tek.com
werner@aecom.yu.edu (Craig Werner) (08/18/89)
In article <4250@orca.WV.TEK.COM>, kris@maui.WV.TEK.COM (Kristen McCormick) writes: > > I'm posting here because I didn't know who else to ask. > I am probably the only person on earth who never had > biology in high school, or anywhere else (I may take it next > term though). So my question is, are blood types inherited? > > Can a father with type A positive blood and a mother > with AB negative (I think) have a child with O positive blood? > If it helps any, the other child has A positive. > In general, if a father has AB blood and the child has type O blood, that is taken as evidence in most states as legal proof of non-paternity. However, cases of mistaken maternity (as above) are pretty rare. And although the probability of faulty recall is the best explanation of the above, there is a way for an AB mother to have a phenotypically type O child. It's called the Bombay blood group. All blood group markers are genetically determined. There are several dozen of them in all, only a few of which are well known: ABO, Rhesus, MNSs, Duffy, and a few others. ABO is the only one to which people are naturally immune to. The gene (designated I) can be in one of three forms: A, B, or inactive. There are two copies. Hence, OO gives O blood group, AA or AO give A, BB or BO give B, and AB gives AB. The mechanism is that either the A-modification or the B-modification is made to another blood antigen (the H antigen). O is defined as the absence of A and the absence of B, not the presence of anything. Hence, if one lacks the H antigen, one has the A/B enzymes, but nothing to modify, and appears O. This was first described in a family in Bombay, hence is called the Bombay blood group. Note well, however, that if this is really the case and the offspring received multiple transfusions, the child is in trouble. Normal O blood contains the H antigen, Bombay O blood does not. Persons with O(Bombay) can only receive other O(Bombay) blood for transfusions. And, by the way, my father was type A, my mother was type B. I'm type O. My family is thus one of the few combinations where both genotypes and phenotypes are known. -- Craig Werner (future MD/PhD, 4.5 years down, 2.5 to go) werner@aecom.YU.EDU -- Albert Einstein College of Medicine (1935-14E Eastchester Rd., Bronx NY 10461, 212-931-2517) "... Has Determined That Cigarette Smoking Is Dangerous To Your Health"
dg@lakart.UUCP (David Goodenough) (08/19/89)
kris@maui.WV.TEK.COM (Kristen McCormick) asks: > Can a father with type A positive blood and a mother > with AB negative (I think) have a child with O positive blood? > If it helps any, the other child has A positive. Nope - it is not possible. There are three genes for blood type (the O A B AB bit, positive and negative are "handled" elsewhere): O, A and B. A and B are both dominant over O, but are "co-dominant" when together. Or to put this another way: there are six possible combinations of O, A and B: OO O blood type AA A blood type BB B blood type OA A blood type OB B blood type AB AB blood type Now, if one parent is AB, that parent will always pass on either an A or a B gene, thus leading to either A or B or AB in the child. Hence an AB parent cannot have an O child. This does not even begin to address the Rhesus factor (positive or negative) - I believe that pos is dominant over neg, but am not as sure: the Bio I took in High School only covered A, B, and O. > My husband and I both have O positive, and so does our daughter, > so I'm assuming heredety has something to do with it. Correct - I think _ALL_ your offspring will be O pos, however if negative is recessive to positive, it is possible for you to have an O negative child. > But is it always? Is it like, absolute, or are there dominant > and recessive like eye color? Anyone? Yep - as I said above O is recessive to A and B, and I think negative is recessive to positive - perhaps someone else can say more about +ve and -ve - I'd kind of like to know myself -- dg@lakart.UUCP - David Goodenough +---+ IHS | +-+-+ ....... !harvard!xait!lakart!dg +-+-+ | AKA: dg%lakart.uucp@xait.xerox.com +---+
chiafari@umbc3.UMBC.EDU (Mr. Frank Chiafari ) (08/31/89)
This is a response to many articles on the net which were close, but not precisely correct. The ABO blood group marker systemm describes a red cell surface antigen (the H-antigen) which can undergo modification by the addition of sugar moities to the protein structure. Either you possess the capacity to modify the H-antigen (A1,A2,B,etc), or you don't(O), or your missing the H- antigen altogether(O-bombay). The modification enzymes, represented as non-O types, are co-dominant, meaning they can each be expressed without exclusion of the other types. These types are detected using purrified sera (with antibodies) from individuals that are immuno-sensitized to a type. Therefore, "A1" individuals can have antibodies to "B" types, or any other type they do not (generally) possess. The gene for the null enzyme activity, "O", i recessive to all other types because it is the lack of activity; O-bomyay is recessive to normal H-antigen. We inherit two copies of each gene (generally), one from each parent. Therefore, an individual who is typed as an "A" could haveither an AA g genotype or an AO genotype (O-bombay is encoded at the locus that produces the H-antigen, NOT at the locus that produces the modification enzymes).The case you gave as an example indicates non-paternity unless both parents are hetero- zygous at the H-antigen locus for O-bombay (one normal copy, one O-bombay), and happened to give the child their O-bombay genes, making him homozygous, a VERY unlikely event. If this was a real paternity case, other blood group or DNA markers could be tested to resolve the situation, looking for more exclusions. Remem- ber however, that the results and interpretation are only as reliable as the test. Wasn't that simple.