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holgerholg
2 years ago

Rhesus positive is dominant, Rhesus negative is recessive.

This means that a child is positive exactly when he gets the rhesus gene positively inherited from at least one parent.

Nevertheless, it cannot be judged in the example above without further information.

Since the mother Rhesus is negative, it is clear that the child gets negatively inherited from her the gene for Rhesus, as she has twice the gene for Rhesus negative (dd).

But there are two options for the Rhesus-positive father. If the father has inherited the Rhesus antigen D (Rh+) from his two parents (DD), he inevitably inherits it and the child then has a gene for negative from the mother, a gene for positive from the father and would therefore always be positive (Dd).

But if the father has a gene for Rhesus Negative and a gene for Rheses Positive (Dd), he can either pass on one or the other gene. Then the probability is that the child Rhesus negative (dd) or Rhesus positive (Dd) will be 50:50.

Since the mother is negative, one knows that the child can be negative (dd) or positive (Dd) at the end. Positive (DD) is not possible. In the embodiment itself, DD and Dd are no difference, but in the case of inheritance, as described above.

isebise50
2 years ago

No.

The Mendelian inheritance rules determine in which succession the genes are passed on.

  • Rh-positive + Rh-positive = Rh-positive or Rh-negative
  • Rh-positive + Rh-negative = Rh-positive or Rh-negative
  • Rh-negativ + Rh-negativ = Rh-negativ

Even if both parents are Rhesus positive, there is a small probability that the two recessive alleles might coincide: then the child would be Rhesus negative, although both parents are positive.

How do you know

You know what? The blood group?

In all “rh-negative” mothers, after birth the child’s blood group is determined from the umbilical cord.

Look here:

https://www.blutspendedienst-west.de/magazin/basiswissen-blut/wie- wird-blutgruppenverbt

Happy for you!

isebise50
2 years ago
Reply to  Markus373

If the mutant is rhe­sus­nega­tive and the Va­ter Rhesus­po­sitive, it can be understood that the child is rhe­sus­tive as the mutant. In this case, there is no need for knowledge about the child’s rhesus factor.

However, it is much more evident that the child is rhe­sus-po­sitive than the father, since rhe­sus-po­si­tive is inherited.

If a rhesus-negative woman expects a rhesus-positive child, the maternal blood can form anti-D antibodies. In most cases, the transmission of child blood into the mother’s blood circulation only occurs during birth, so that there is often no danger for the first child.

However, if the mother is again pregnant with a rhesus-positive child, her antibodies can enter the bloodstream of the unborn, severely impair his development and even be life-threatening for the child.

Therefore, each rhesus-negative woman gets a prophylactic injection of anti-D-inhibition louvins in pregnancy, after a birth or miscarriage and also after an abortion.

This general gift was therefore indicated so far, since the rhesus factor of the child could not be determined easily during pregnancy and only after birth was it determined whether the child is rhesus-positive.

However, a safe method for determining the fetal rhesus factor from maternal blood is now offered at the expense of statutory health insurance.

Rhesus-negative pregnant women are usually informed by their gynecologist about the possibility of allowing the rhesus factor of their child to be determined before birth in order to avoid unnecessary anti-D-phylaxis (early from the 12th SSW).

In these pregnant women, if they take advantage of the rhesus factor determination and the child is also “negative”, an anti-D-Prophylaxe can be dispensed with.

PeterP58
2 years ago

No, not necessarily… the Mendel rules are also in place.