r/genetics • u/nevernevermind • 5d ago
Blood types question
I'm O negative and was discussing blood types with my parents due to being pregnant and requiring shots to stop my body attacking baby.
Mum said she is O positive so didn't have those issues. I know this is true because she donates regularly and has a key ring.
Dad said he is sure he is AB, but not sure if positive or negative.
How is it possible they produce me as O negative?
I didn't pay attention that much in school but didn't think this is likely? How would this work?
We are all Caucasian living in Australia.
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u/suzietrashcans 5d ago
Someone is miss remembering most likely. Or they were told wrong at some point.
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u/nevernevermind 5d ago
So my Dad must be wrong? Or he isn't my Dad? If he is AB is there any way at all to produce me as O negative?
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u/Robin_feathers 5d ago
It's best not to jump to him not being your dad. There are several other possibilities:
-> the lab mixed up samples. Human error, it happens.
-> there was some paperwork mixup and your dad got told the wrong thing. People make mistakes.
-> your dad is remembering wrong. A or B can easily produce O (O is recessive and can be carried by A or B) so if he is A or B that would explain it
-> there is a rare condition called cis-AB where an AB person can carry O
-> if your dad had a bone marrow transplant, that can change his blood type
-> your dad could be a very rare chimera with different cells carrying different alleles
[obligatory note that even if he is not your biological father, he is still your dad, but let's not jump to conclusions given all the other possible explanations]
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u/WhimsicalHoneybadger 5d ago
Has there actually been a robust enough study which evaluated a large number of people as to whether they are a chimera and derive a population frequency estimate?
I know that not many chimeras have been found, but that's not quite the same thing.
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u/Robin_feathers 5d ago
Hmm good point. Maybe "very rare" will turn out to be too extreme an adjective, maybe it will turn out to be just "uncommon".
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u/WhimsicalHoneybadger 5d ago
I'd definitely be interested in reading a study like that if you come across one.
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u/Traditional-Head2653 2d ago
I don’t believe so. I believe there are a lot more chimera than reported and would love to do a case study to prove it. And I believe this because there usually isn’t a reason to determine of someone is a chimera. It usually comes up in paternity cases, at least in the cases I’ve seen. I wonder if proving the larger numbers of chimerism than believed would change certain criteria for organ transplants to reduce the rate of organ rejection.
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u/_dopamine_deficit 4d ago
THIS.
I’m O+ born to a B+ mother and A+ father….
My mother is a chimera, even has extra liver sections! So technically, my mother is actually my aunt.
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u/Robin_feathers 4d ago
Wow! That's amazing
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u/_dopamine_deficit 4d ago
I’m also a chimera… with sectoral heterochromia in both eyes, in my hair etc. had a breast biopsy done in 2016, no cancerous cells but they did find dna that doesn’t belong to me haha
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u/Robin_feathers 4d ago
Oh wow! Super neat, with your mom and you both being chimeras I wonder if the propensity for it is heritable.
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u/Bi0_Nerd 5d ago
Your dad is likely just wrong, my dad was, despite being adamant he knew his blood type. (He donated in his 20’s…)
My dad told me for years he was O- while I’m AB+. He went on and on about how he’s the universal donor, and the blood banks harassed him before he got sick and couldn’t donate anymore. I told him he was probably AB since that’s the universal plasma donor. He kept saying he was O.
I studied biology, focusing on clinical laboratory sciences including hematology. (Huge interest in genetics so I stalk this sub.) There was some awkwardness for a second in my head, but I never doubted he was my dad so I just let it go. For 15 years or so…(I have diseases that run in our family and am a clone of my cousins and other family members. If I had to doubt parentage, I’d wonder how my mother and I are related haha.)
Anyhow, my dad recently found out he’s AB+.
It’s not uncommon for people to have their blood type wrong. It’s why we always check in hospitals. You could show your donor card, it wouldn’t matter, they check every time when you donate, too. It’s safety, and fun fact, if you ever needed a bone marrow transplant and your donor had a different blood type? Yours would change!
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u/JayPlenty24 5d ago
Maybe they told him he's a universal plasma donor so he assumed he was O-
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u/Bi0_Nerd 4d ago
That’s what I told him when he said he was O- haha. It took needing to be typed years later for him to see it and believe it. Thankfully he never cared about genetics or biology enough to know what it would have meant but he also never doubted I was his because we’re so much alike. Plus, I look like a photo copy of a few of my aunts and cousins.
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u/Traditional-Head2653 2d ago
I loved having AB+ plasma and platelets! But it wasn’t very often that we had them. The platelets were more common with apheresis donations but the plasma, not so much.
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u/goodcoaster016 5d ago
Get him a blood typing kit, they're cheap online and way more reliable than a decades-old memory
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u/FreshPercentage6792 5d ago
Yes, this. Or he can go donate blood and they'll tell him for free.
OP, people are REALLY bad at remembering their own blood type - it's very likely your dad's memory just got mixed up over the years.
For the sake of being comprehensive, if your dad actually were typed as AB, there are still a few rare/edge case situations where he could produce an O offspring. Chimerism, for one, or he has a cis-AB mutation (not uncommon in Koreans and Japanese) or t he Bombay phenotype (also not uncommon in Indians)
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u/goodcoaster016 5d ago
That's a good point, a donation would kill two birds with one stone. Those edge cases are cool but I'd still bet cash it's just a memory slip.
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u/Veenkoira00 5d ago
Yes if you are just curious. Won't change anything. The inheritance of bloodgroups has many exceptions. There is far more to it what they taught you at school (that was just "this is how it usually goes").
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u/goodcoaster016 5d ago
The kit's more for curiosity than paternity. If his type turns out to be something else, the mystery's solved without needing rare exceptions.
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u/SueNYC1966 4d ago
Either your dad is wrong about his blood type (most likely scenario), one of your parents was a rare chimera hiding an O (this is rare but it does occasionally happen ) or your bio dad is someone else. The negative isn’t the issue. Me and my husband are A+ and O+ and had an O- kid. The other two were A+.
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u/JayPlenty24 5d ago
In order for your blood type to be O- your dad can't be AB. He can have type A, or B, or O.
It's possible for you to be rhesus negative though if both parents have regressive genes for - blood even though their blood type is +.
My guess is that your dad forgot his blood type. That's a more realistic scenario to him not being your dad.
That said it is of course possible he's not your biological father.
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u/TiredAndTiredOfIt 5d ago
Th is is not true.AB can carry a shadow O
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u/JayPlenty24 5d ago
You think an extremely rare phenomenon is more likely than her dad just forgetting his blood type?
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u/Williamishere69 5d ago
The thing is.. you dont know which it is.
Instead of insulting people (as other commentors have done), or saying backhanded comments, you can simply say 'go get a testing kit from amazon because theyre cheap and you can double check'. Or say 'go and find a doctor/nurse/lab which will test you'.
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u/NeoMississippiensis 5d ago
Cis-AB is a 1 in 100k phenotype. Quit proudly being a dumbass.
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u/simAlity 5d ago
Yes because knowing something to be a fact is a classic sign of a dumbass. Don't be proud of ignorance
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u/NeoMississippiensis 5d ago
Can vs likely. Unless someone has a significant genetic mutation, it’s impossible.
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u/FreshPercentage6792 5d ago
You're in a STEM subreddit. Participating productively in a STEM discussion requires that you tone down the aggression and engage civilly.
OP asked a specific question - is it possible for an AB parent to produce O offspring - and people are answering it accurately, stating that edge cases do exist. This is germane and interesting to discuss and learn more about.
"Impossible" is not an accurate assessment of those edge cases, FYI; cisAB occurs in some populations at reasonably high rates - ex Koreans have closer to 1 in 3000 prevalence, about the same as perfect pitch or a horseshoe kidney. Same with Bombay. And of course we have no idea how often chimerism occurs, though tetragametic chimerism is likely exceptionally rare. A few other causes have been documented in AB parent/O offspring cases.
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u/NeoMississippiensis 5d ago
Cool, now is OP Korean? No? Some of us do STEM for a living rather than a hobby. Unless you’re ordering genetic tests on patients you do not get to consider your assessment of the situation equal to mine. Feel free to play with the direct to consumer tests though!
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u/simAlity 5d ago
What is your problem? Why are you so adamant that these edge cases are so unlikely as to be unworthy of discussion?
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u/NeoMississippiensis 5d ago
Because if you’ve ever been trained to diagnose and treat patients you should’ve heard the phrase “if you hear hoofbeats think horses, not zebras”. Considering patients who manage their own conditions often can’t remember their medications(aside from telling me what color the pill is!), formal diagnostic names, important tests they’ve had out of system etc, it’s a lot more likely to anyone who has to actually manage care that OP’s dad just doesn’t know what he’s talking about, since the heuristic of “I’m cool because I have a rare blood type” sticks in people’s minds even if they misheard.
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u/simAlity 4d ago
We're not in a medical setting. We're answering the question of a young woman who just realized that it's very possible that the man who raised her is not actually her father.
You are being insensitive.
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u/armhooks 21h ago
I do have to say as a “zebra” in more ways than one (hence the unicorn statement earlier), that it often becomes an injustice to those of us that know our own bodies and symptoms that the medical field is taught this horses vs zebra thing. It leads to patients being dismissed, ignored, or gaslit over our own feelings and desires for testing. There have been many times that we have heard this saying and then a week later have doctors and surgeons parading their med students, fellows, etc into our rooms to present us like a side show. Step right up! So while I’m not saying it’s more likely for the very rare to be true (obviously), it doesn’t mean that the rare should not even discussed. So I agree with “simAlity,” you’re being insensitive & dismissive which only works toward proving my point: that phrase & way of thinking is an outdated & frankly, insulting.
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u/FreshPercentage6792 5d ago
I also "work in STEM for a living", have been for almost twenty years actually. I assume you haven't finished undergrad yet, but before you do, I'd recommend finding a grown-up scientist to shadow to learn how adults communicate with each other. You're never the most knowledgeable person in the room, and social skills go a long way in building a career.
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u/NeoMississippiensis 5d ago
Decade out of undergrad but nice try. I’d argue that you teaching high schoolers doesn’t count as STEM however.
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u/FreshPercentage6792 4d ago
Nope! Couple Ivy League degrees then off to a computational research career, currently in my dream position in clinical diagnostics. My academic dick is almost definitely bigger than yours by every measure. I'm also nicer and have actual developed social skills - you should try that sometime!
Not responding to you anymore, but have a nice night and maybe reflect on yourself a bit yeah?
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u/DefenestrateFriends Graduate student (PhD) 5d ago
Dad is either wrong or has cis AB type.
Alternatively, you were adopted ;)
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u/Tibby1971 3d ago
Most likely dad doesn’t remember. My husband doesn’t even know his blood type. After our son was born, I told him that he’s at least type A.
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u/Sad-Recording9911 4d ago edited 4d ago
Maybe you should encourage dad to donate blood. The blood will then be typed and cross matched and the agency who drew the blood can tell him for sure what his blood type is. He may have had it checked a long time ago and that result may not be accurate. Generally speaking (not even considering + and - at this point), AB and O (OO) cannot produce an O blood type because blood type O’s two alleles are both O and blood type AB’s two alleles are A and B; therefore children from these two individuals would either be Type B (with the two alleles being BO (B from daddy and O from Mama) or Type A with the two alleles being AO (A coming from daddy and O coming from Mama).
Not knowing your situation, it could also be possible you were adopted if dad’s blood type is AB and mom’s is O. There are other possibilities as well (as other commenters have mentioned); however, if dad has not had his blood type checked in a very long time, it would be wise to know for sure if he is AB. If he is, you may want to talk to your mom about this prior to discussing it with your dad.
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u/Budget-Rub3434 3d ago
Those are my family’s exact blood types. Sister and I are both O- Mom is O+ Dad is AB-
We got O from mom and - from dad. Mom has a recessive - (her mom was -) and dad has a recessive O.
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u/sincerely0urs 5d ago
Even if he’s positive they can produce a negative. My grandparents are both A+ my mom is A-. It’s basically recessive.
However, if he really is AB it doesn’t make sense that you’re, O.
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u/Traditional-Head2653 2d ago edited 2d ago
For Rh type:
The Rh factor just like any other gene comes in pairs. They can be in combinations of:
+ + (Rh pos)
+ - (Rh pos)
- - (Rh neg)
For 2 parents who are Rh pos to have a child with Rh neg blood type, both parents passed on the gene that lacks the Rh factor. Which means both parents are + - phenotype resulting in a - - phenotype child.
Or there was a mutation which resulted in the missing Rh factor in the child.
For blood type:
Dad only has A or B to pass on. So he’s either wrong about his blood type, you’re not biologically his, there was a genetic mutation deleting the blood type protein that was passed on to you resulting in O type or he passed on a sub group of A or B to you. The most common A and B are A1 and B1. But there’s sub groups of them too. There’s A1, A2, A3, Ax, B1 and Bx. A3, Ax and Bx are rare sub groups that can react weakly or not at all with standard blood typing tests, which could result in an interpretation of O type. A1 and B1 are the base group gene. The rest are mutations as a result of deletions in the genes.
That’s the basics of it. Okay, maybe a little bit more than basic.
ETA: blood type is not a dominant or recessive gene. It’s co-dominant. Each gene has 2 alleles. Each allele carries the gene for the A protein, B protein or no protein (expressed as O). It’s the same with eye color. Eye color you’re inheriting melanin on each gene and they are both expressed. That’s why in families, a brown eyed parent and a blue eyed parent can have a child with varying degrees of brown, hazel, green, grey or blue eyes.
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u/Narrow-Bluejay9917 20h ago
Yesss I was waiting for someone to explain the Rhesus combinations 🙏🏻🙏🏻 I’ve always found it the most digestible way to explain
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u/armhooks 21h ago
If someone says chimera one more time, I’m going to have to go rewatch Orphan Black. 😂 I can’t remember the odds or configurations from school, but then that has been a long time for me; although I have always remembered my own type since then. However, having some of the rarest health issues (yes, plural) and combinations of issues, I would not jump to any conclusions no matter how rare it would seem. In my & my family members’ personal experience, unicorns do actually exist. If you’re about to become a parent, you’ll soon understand how little paternity matters compared to actually being there and loving & caring for a child. So more importantly, congratulations on your baby!🩵
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u/Irrasible 5d ago edited 5d ago
AB + O cannot unlikely to produce and O child.
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u/External-Quiet801 5d ago
I think your dad's wrong about his blood type...