How Does a Baby Get Its Blood Type

-A curious adult from Massachusetts

November eighteen, 2004

Well, your blood is definitely all your own. But because of how the genetics of blood type works, it could seem like you have your mom's blood type, your dad's claret blazon, or a mix of the two.

For every gene, you go two copies -- one from your mom and one from your dad. Even though the two copies are for the same gene, you tin can become dissimilar versions from each parent. These dissimilar versions are called alleles.

Alleles are a piffling similar cars -- the aforementioned make and model of car can come with either ii doors or iv doors. The cars do the same matter (get you where you're going!) simply they are slightly different.

At present allow's talk nearly the genes for claret type. There are ii main genes. I factor is for the ABO type. This gene codes for a protein that is on the surface of your blood cells. The different versions or alleles for the blood blazon protein are called A, B, and O.

The other gene is for another protein on your blood cells called the Rh factor. The alleles are called plus (+) and minus (-). You can learn more about the Rh factor and its implications for wellness in the respond to another question here:

It doesn't thing what type your blood is unless you demand a blood transfusion. In that case it is very important that you receive claret that is of the same blazon equally yours (or type 0-, which I'll talk about at the end). If yous get the wrong type of claret your trunk volition see the transfused claret cells as foreign attackers and will destroy the new blood cells, making you very ill.

The two genes for blood blazon are inherited separately, so nosotros'll talk about them individually, and then put it all together at the end.

Let's take an case of a mom who has claret blazon AB, and a dad who has claret type A. You might observe that the mom has ii letters in her blood type. This is because she has the two different alleles she got from her parents (A and B). But so why does the dad but take one letter of the alphabet? It's because he either has two A alleles or he has i A allele and one O allele. This is simply the manner people write these things.

There isn't any way to tell what kind of blazon A claret the dad has unless we know the blood types of his parents. For now we're going to assume that he has one A allele and one O allele, and we're going to write out both alleles when we talk nearly the possible blood types of the kids to make things easier for us.

To effigy out what blood type the kids of these two parents can have, nosotros can utilise a genetics tool called a Punnett foursquare. Information technology'southward really just a chart that helps us organize the genes. We'll put the mom'due south alleles across the peak, and the dad's alleles down the side.

Each box in the chart represents a possible combination of the alleles donated by each parent (each box gets ane entry from mom, one entry from dad). Nosotros tin can say what pct chance a child has of having a item blood type by how many times that blood type shows upwards in the chart (one out of iv is 25%, 2 out of four is 50%, etc.).

If nosotros fill in the possible mixtures of alleles each child could go far our case, nosotros get a chart that looks like this.

So the possible blood types are AA, AB, AO, and BO. Like I explained for the dad'south blood type before, people with two A alleles (AA) and people with one A allele and one O allele are both chosen type A (the same thing goes for type B). And then, the kids of these parents take a 50% take a chance of being what we call blazon A, a 25% take chances of being blazon B, and a 25% chance of being blood type AB.

You tin can do the same with the Rh gene factor. Let's say that the mom was Rh-positive (with i + allele and i - allele, though she could as well have 2 + alleles) and the dad is Rh-negative (meaning both of his Rh alleles are -).

There are 2 possibilities for the Rh-status of the kids. They have a fifty% risk of being Rh-positive (+/-) and a 50% chance of existence Rh-negative (-/-).

Permit'south put it all together. The mom was claret type AB+, and the begetter was blood blazon AO-. A Punnett square for this is shown below.

The possibilities for their kid's blood type are. AA+, AA-, AB+, AB-, AO+, AO-, BO+, and BO-. (The Punnett square can also tell us that at that place is a one in 4 adventure for either A+ or A-, and a 1 in viii run a risk each for AB+, AB-, B+, and B-.)

Y'all tin can see that two of these, AB+ and AO- (in blue), are exactly like i of the parents. All the others are mixtures of the 2.

This is simply one of the many examples of how the instructions for making you that are in your genes make you lot like your parents, only at the same fourth dimension unique.

I said at the first that if you needed a blood transfusion that you lot could either get the same blood type as your own, or else you could become O- blood. Simply why?

People with O- blood are called universal donors because they can give blood to anyone. The reason is that the O and the - really mean that their blood cells don't have any versions of either of the two proteins coded for past these gene on their surface. And then at that place is nothing for a person's body to encounter as a foreign assailant. Unfortunately for these people, it too ways that their bodies will see all other blood types as foreign attackers and that they tin can only receive other O- blood.

Is there a universal acceptor claret type? Yes, it is AB+. These people are lucky considering their bodies are used to seeing both the A and B versions of the protein, and they are used to seeing the Rh+ gene. Then no matter what kind of blood they receive, their bodies won't see it equally a foreign assaulter. Just well-nigh 3% of the population is this lucky (http://chapters.redcross.org/br/northernohio/INFO/bloodtype.html).

By Erin Cline

rodriguezswitithe.blogspot.com

Source: https://genetics.thetech.org/ask/ask71

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