The original question was:
How could four major blood types (A, B, AB, and O) and two Rhesus factors (positive and negative), come from only one pair of Humans? What blood type were Adam’s and Eve? Is there any possibility genetic mutations generated blood type changes?

Answer by Diane Eager

ABO Inheritance

The ABO and Rh blood grouping systems can easily have been inherited from one couple. Let’s start by looking at the way the ABO groups are inherited today. Genes for the ABO system come in three variations A, B and O. Because you have two copies of each gene it is possible to inherit two different variations. However, A and B genes always predominate over O genes. Therefore, to be blood group A you can either have two A genes, i.e. a genotype of AA, or one A and one O, i.e. genotype AO. Blood group B people can have two B genes, i.e. genotype BB, or a B and an O gene, i.e. genotype BO. Group AB people have one A and one B gene, i.e. genotype AB. Group O people have two O genes, i.e. genotype OO.

A couple whose gene combinations are AO and BO could give rise to all four groups in their children. Let’s work it out. Suppose the mother was AO and the father BO. Children inherit one gene from each parent. Therefore, children could inherit the following combinations:

Mother’s A plus Father’s B: child’s blood group AB (genotype AB)

Mother’s A plus Father’s O: child’s blood group A (genotype (AO)

Mother’s O plus Father’s B: child’s blood group B (genotype (BO)

Mother’s O plus Father’s O: child’s blood group O (genotype (OO)

The ABO genes are not linked to the sex of the parents or the children, so the same combinations could occur if the mother was BO and the Father AO. However, I don’t think Adam and Eve were the above combination because O is a mutation that stops the formation of the A molecule. In the beginning, everything God made was very good. There would not have been any defective genes.

ABO Genes

Let’s look at what the A and B groups actually refer to on the blood cells. The A and B of the ABO blood groups refer to two different molecules that are attached to the surfaces of red blood cells. Group A people only make the A molecule. Group B people only make the B molecule. Group AB people make both, and Group O people make neither. These molecules are attached to the red cell surface by another molecule named H, so the ABO blood group system is sometimes called the ABH system, as the vast majority of Group O people still have the H molecule. There is a rare form of Group O where H is missing, so even if these people could make the A or B molecules there is nowhere for them to attach it to the cell.

The A and B genes actually code for two different enzymes that attach differing sugar molecules to the end of the H molecule. The A enzyme attaches a molecule named N-acetyl-galactosamine molecule to the H molecule. The B enzyme attaches a molecule named galactose. The gene for O is a deletion/frameshift mutation of A, and produces a non-functional protein that doesn’t attach any other molecules to the H molecule.

Because the O gene is very common and is present in all races, I suspect the O mutation occurred fairly early in the history of the human race. Most likely it was already present in Noah’s family at the time of the Flood when the human population was reduced to eight people. Therefore, even if only one of Noah’s sons or daughters-in-law had it, it would be a significant proportion of the gene pool. It seems to be a harmless mutation, so it would have spread easily through the population, without causing any loss of fitness or reproductive life.

What about Rh?

The Rh system is expressed as positive and negative. It involves two genes named RHD and RHCE which code for two proteins embedded in the red cell membrane. In general the presence or absence of the RHD gene determines Rh status. In most Rh negative people, the RHD gene is missing altogether. In others the gene is present but a mutation causes it to be non-functional.

Like the ABO genes, each person has two copies of the Rh genes, but only one normal RHD gene is required for a person to be Rh positive. Rh negative people have two negative, i.e. missing or mutated genes. Rh negative status can cause serious disease and even death in babies of Rh negative mothers. Since death has resulted only from man’s disobedience, you can be assured God did not build this problem into a good world. Therefore, Rh negative genes are the result of the general degeneration of the human genome that occurred after the Fall, or more likely, after the Flood.

What were Adam and Eve’s Blood Groups?

Adam and Eve would not have had any missing or defunct genes. Therefore, they would have had the A and B genes and normal Rh genes. Therefore, they both could have been AB positive, or one could have been A positive and the other B positive.

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