# What if my blood is the Bombay Phenotype testing as O ? **URL:** \ **Category:** Factual Questions\ **Created:** [May 17, 2006, 9:03pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162 "2006-05-17T21:03:14Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![js\_africanus](https://avatars.discourse-cdn.com/v4/letter/j/87869e/32.png) [@js\_africanus](https://boards.straightdope.com/u/js_africanus)\ **Post date:** [May 17, 2006, 9:03pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/1 "2006-05-17T21:03:14Z")
I think I’m O negative, but my parents are both positives (at least one is O positive). Because the family resemblances are so striking, it’s been a source of comic relief for years. My cousin the doctor said I might be a Bombay negative. I never got a chance to grill her on what that means. I’m bored, so I just did a little Googling and read the Wikipedia entry. I confess, I really don’t understand what I’m reading. If I’m O[sub]h[/sub], is my blood super-rare and highly unobtainable, and can O[sub]h[/sub] only _receive_ blood of that type? E.g., should I give blood as much as possible and bank for myself if possible? Don’t be afraid to give more explanation than merely answering the above questions. When I read about blood types, my eyes glaze over and I’ve no idea what I’m reading. Thanks! ---
**Author:** ![Anne\_Neville](https://avatars.discourse-cdn.com/v4/letter/a/b9e5f3/32.png) [@Anne\_Neville](https://boards.straightdope.com/u/Anne_Neville)\ **Post date:** [May 17, 2006, 9:14pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/2 "2006-05-17T21:14:50Z")
> [@js\_africanus](#): > > I think I’m O negative, but my parents are both positives (at least one is O positive). Because the family resemblances are so striking, it’s been a source of comic relief for years. My cousin the doctor said I might be a Bombay negative. I never got a chance to grill her on what that means. You might. Or your parents might each have one copy of the gene for Rh positive (which is dominant) and one copy of the gene for Rh negative, and you just happened to inherit two recessive genes. I’d say that’s probably more likely than your being a Bombay negative. I don’t know my blood type, but I do know that it is positive and my mother’s blood type is negative. So I must have one copy of the Rh-positive gene and one copy of the Rh-negative gene. ---
**Author:** ![FlightlessBird](https://avatars.discourse-cdn.com/v4/letter/f/cdc98d/32.png) [@FlightlessBird](https://boards.straightdope.com/u/FlightlessBird)\ **Post date:** [May 17, 2006, 11:12pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/3 "2006-05-17T23:12:59Z")
Can I add a question? My mother is (O-) “Universal donor” I am (AB+) “Universal receiver” What blood type was my father? (or what blood types could he have been?) ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [May 17, 2006, 11:16pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/4 "2006-05-17T23:16:19Z")
> [@FlightlessBird](#): > > Can I add a question? > > My mother is (O-) “Universal donor” > I am (AB+) “Universal receiver” > What blood type was my father? (or what blood types could he have been?) Wouldn’t he have to have been AB too? ---
**Author:** ![Captain\_Amazing](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Captain\_Amazing](https://boards.straightdope.com/u/Captain_Amazing)\ **Post date:** [May 17, 2006, 11:22pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/5 "2006-05-17T23:22:35Z")
> [@FlightlessBird](#): > > Can I add a question? > > My mother is (O-) “Universal donor” > I am (AB+) “Universal receiver” > What blood type was my father? (or what blood types could he have been?) Are you sure you weren’t adopted? 🙂 ---
**Author:** ![MLS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MLS](https://boards.straightdope.com/u/MLS)\ **Post date:** [May 17, 2006, 11:32pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/6 "2006-05-17T23:32:59Z")
From my limited knowledge of genetics, I don’t see how an O- woman could give birth to an AB+ child, unless there was a particular mutation. Type O and negative are both recessive genes. So she has to pass on a Type O gene and an Rh negative gene. That leaves the father to pass on either an A or a B or neither. He can also pass along either an Rh negative or an Rh positive. That leaves the child as anything else EXCEPT AB+. Either that or my understanding of the heritability of blood types is completely off base, which is also possible. ---
**Author:** ![Captain\_Amazing](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Captain\_Amazing](https://boards.straightdope.com/u/Captain_Amazing)\ **Post date:** [May 17, 2006, 11:41pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/7 "2006-05-17T23:41:08Z")
> [@elfkin477](#): > > Wouldn’t he have to have been AB too? No, not normally. Remember how blood typing works. There are two different clotting proteins in blood, A and B, and each of these are created by a specific allele. So someone with AB blood type has to have both alleles for A and B, which means that they had to inherit an A allele from one parent and a B allele from the other. Someone with blood type O, like Flightless Bird’s mom, can’t have a child who has blood type AB, like Flightless Bird. So, it’s likely thet either Flightless Bird got his/her blood type wrong, his/her mom’s blood type wrong, or that Flightless Bird’s mom isn’t his/her biological mom. ---
**Author:** ![Rysdad](https://avatars.discourse-cdn.com/v4/letter/r/7cd45c/32.png) [@Rysdad](https://boards.straightdope.com/u/Rysdad)\ **Post date:** [May 18, 2006, 12:36am UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/8 "2006-05-18T00:36:49Z")
> [@Captain Amazing](#): > > Someone with blood type O, like Flightless Bird’s mom, can’t have a child who has blood type AB, like Flightless Bird. So, it’s likely thet either Flightless Bird got his/her blood type wrong, his/her mom’s blood type wrong, or that Flightless Bird’s mom isn’t his/her biological mom. See if I get this right… Someone with AA or AO is an A, and someone with BB or BO (no jokes, please) is a B, right? Someone with O must be OO, right? Therefore, someone with OO could _not_ have passed on either the A or the B to an AB child. Right? ---
**Author:** ![Antigen](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Antigen](https://boards.straightdope.com/u/Antigen)\ **Post date:** [May 18, 2006, 12:44am UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/9 "2006-05-18T00:44:32Z")
> [@js\_africanus](#): > > I think I’m O negative, but my parents are both positives (at least one is O positive). Because the family resemblances are so striking, it’s been a source of comic relief for years. My cousin the doctor said I might be a Bombay negative. I never got a chance to grill her on what that means. Blood types are based on the type of substances (glycoproteins) present on the red cells. I explained it all over in [this thread](http://boards.straightdope.com/sdmb/showpost.php?p=7400559&postcount=61) if you’d like to have a quick look. The thing is, the A and B substances aren’t directly attached to the red cell themselves. Essentially, they’re two chemical modifications of a third substance, called the H substance, which is embedded in the red cell membrane of nearly everyone on the planet. If your cells only have the unmodified H substance on them, you’re Type O. (I know, makes more sense to call it Type H, but there you have it.) The whole H thing is usually never discussed, because it can get confusing and it’s not really going to affect anything with routine blood typing. The Bombay O phenotype occurs when the H gene is missing, and is _extremely_ rare. It’s a separate gene from the A/B gene, and so even if you’ve got the genetics to be a type AB, and you’re missing the H substance, you’re going to type as an O in the lab. The problem with transfusing a Bombay O phenotype person is that the body makes antibodies against things it doesn’t recognize. So this person will have antibodies against A and B and H, and since everyone else’s blood has at least the H substance, even Oneg people, we can’t use it to transfuse him. These people, then, are encouraged to make autologous donations, which are then frozen and kept in case a transfusion is ever needed. But… and I may be wrong, so hopefully someone with more blood experience can help me out here… as far as I know the Rh system is completely isolated from the ABO (and H) system and so just the fact that you’re type Oneg when your parents are Opos really shouldn’t be causing anyone to whip out the O bombay suggestion. Like \*\*Anne Neville \*\*said, your parents probably have one Rh pos gene each, and you got the recessives and ended up negative. ---
**Author:** ![js\_africanus](https://avatars.discourse-cdn.com/v4/letter/j/87869e/32.png) [@js\_africanus](https://boards.straightdope.com/u/js_africanus)\ **Post date:** [May 18, 2006, 12:57am UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/10 "2006-05-18T00:57:08Z")
> [@Antigen](#): > > But… and I may be wrong, so hopefully someone with more blood experience can help me out here… as far as I know the Rh system is completely isolated from the ABO (and H) system and so just the fact that you’re type Oneg when your parents are Opos really shouldn’t be causing anyone to whip out the O bombay suggestion. Well, she was only in her residency at the time, and you know how _they_ can be. 😃 ---
**Author:** ![cerberus](https://avatars.discourse-cdn.com/v4/letter/c/71e660/32.png) [@cerberus](https://boards.straightdope.com/u/cerberus)\ **Post date:** [May 18, 2006, 1:17am UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/11 "2006-05-18T01:17:06Z")
From [Wiki Does Bombay](http://en.wikipedia.org/wiki/Blood_type), the Bombay type is its’ own thing, and apparently only people with Type Bombay can only donate/receive type Bombay. > [@](#): > > Bombay phenotype > > Individuals with the rare Bombay phenotype (hh) do not express substance H on their red blood cells, and therefore do not bind A or B antigens. Instead, they produce antibodies to H substance (which is present on all red cells except those of hh genotype) as well as to both A and B antigens, and are therefore compatible only with other hh donors. > > Individuals with Bombay phenotype blood groups can only be transfused with blood from other Bombay phenotype individuals. Given that this condition is very rare to begin with, any person with this blood group who needs an urgent blood transfusion may be simply out of luck, as it would be quite unlikely that any blood bank would have any in stock. Those anticipating the need for blood transfusion (e.g. in scheduled surgery) may bank blood for their own use (i.e. an autologous blood donation) but this option is not available in cases of accidental injury. > > Patients who test as type O may have the Bombay phenotype if they have inherited two recessive alleles of the H gene, (their blood group is Oh and their genotype is “hh”), and so do not produce the “H” carbohydrate that is the precursor to the “A” and “B” antigens. It then no longer matters whether the A or B enzymes are present or not, as no A or B antigen can be produced since the precursor antigen is not present. > > Despite the designation O, Oh negative is not a sub-group of any other group, not even O negative or O positive. When this blood group was first encountered, it was found not to be of either group A or B and so was thought to be of group O. But on further testing, it did not match even for O negative or O positive because of the absence of antigen ‘H’. The H antigen is a precursor to the A and B antigens. For instance, the B allele must be present to produce the B enzyme that modifies the H antigen to become the B antigen. It is the same for the A allele. However, if only recessive alleles for the H antigen are inherited (hh), as in the case above, the H antigen will not be produced. Subsequently, the A and B antigens also will not be produced. The result is an O phenotype by default since a lack of A and B antigens is the O type. The blood phenotype was first discovered in Bombay, now known as Mumbai, in India. **Non-Wiki References** [What Is The Bombay Phenotype?](http://www.knowledgene.com/public/view.php3?db=gene_school&uid=59#6) [The A, B, and H Blood Group Structures](http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=glyco.section.1068) [ABO BLOOD GROUP SYSTEM:ANTIGENS AND ANTIBODIES](http://matcmadison.edu/is/hhps/mlt/mljensen/BloodBank/lectures/abo_blood_group_system.htm) > [@](#): > > The Bombay blood group lacks H gene and therefore cannot make H antigen (H substance). Since the H substance is the precursor for the A and B antigens, these antigens also are not made. The cells type as O and the serum has anti-A, anti-B, and anti-H since the individual lacks all of these antigens. Anti-H agglutinates O cells. The only cells Bombay individuals do not **agglutinate** are from other Bombay blood people since they lack the H antigen. ---
**Author:** ![cerberus](https://avatars.discourse-cdn.com/v4/letter/c/71e660/32.png) [@cerberus](https://boards.straightdope.com/u/cerberus)\ **Post date:** [May 18, 2006, 1:21am UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/12 "2006-05-18T01:21:52Z")
From the first non-Wiki link above: > [@](#): > > What Is The Bombay Phenotype? > > As with most things in life, there is an exception to the rule of blood types. Sometimes a child can display a phenotype that does not correspond to the phenotypes of the parents. For example, a Type A father and a Type O mother can give birth to a baby with the blood type AB. Logically this seems impossible; how can a mother with type O and father with Type A have a baby that is neither type A nor type O? The answer lies within another antigen. **The H antigen is the precursor to the A and B antigens. If the H antigen is inherited as recessive (hh), it will never develop into an A or a B antigen.** The result is that the phenotype (the trait that is actually expressed in the person) will appear to be O, even though the genotype (the combination of the two alleles) might be A or B. When this occurs, it is possible for a child to have a phenotype that does not correspond with the parents. [Hence, blood tests for paternity purposes are not as accurate as those performed by testing DNA.] The H factor is not related to the Rh factor, so Rh status has doodly squat to do with Bombay. ---
**Author:** ![Captain\_Amazing](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Captain\_Amazing](https://boards.straightdope.com/u/Captain_Amazing)\ **Post date:** [May 18, 2006, 2:30pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/13 "2006-05-18T14:30:43Z")
> [@Rysdad](#): > > See if I get this right… > > Someone with AA or AO is an A, and someone with BB or BO (no jokes, please) is a B, right? Someone with O must be OO, right? Therefore, someone with OO could _not_ have passed on either the A or the B to an AB child. > > Right? That’s right. ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [May 18, 2006, 4:21pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/14 "2006-05-18T16:21:14Z")
> [@FlightlessBird](#): > > Can I add a question? > > My mother is (O-) “Universal donor” > I am (AB+) “Universal receiver” > What blood type was my father? (or what blood types could he have been?) If you are in fact AB then neither of your parents could have been O. This means you have an error in your facts somewhere… either you are not AB or your mother is not O. ---
**Author:** ![Antigen](https://avatars.discourse-cdn.com/v4/letter/a/848f3c/32.png) [@Antigen](https://boards.straightdope.com/u/Antigen)\ **Post date:** [May 18, 2006, 4:36pm UTC](https://boards.straightdope.com/t/what-if-my-blood-is-the-bombay-phenotype-testing-as-o/357162/15 "2006-05-18T16:36:55Z")
> [@Brain Wreck](#): > > If you are in fact AB then neither of your parents could have been O. This means you have an error in your facts somewhere… either you are not AB or your mother is not O. Unless she’s a Bombay O, in which case she may have the genes for A and/or B but just isn’t expressing them. But the chances of that are spectacularly small.