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There are many different antigens on the membranes of red blood cells. Some of these...

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tchrome | eNoter

Posted May 28, 2013 at 1:56 PM via web

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There are many different antigens on the membranes of red blood cells. Some of these can be used to determine paternity (e.g. the ABO group, the MN series and the Rhesus factor). This is a relatively quick, cheap and easy process that can be carried out on a simple blood sample.

In a court case concerning a paternity dispute, each of two men claimed three children to be his own. On the basis of the blood groups of the men, the children and their mother shown below, can the paternity of the 3 children be established?

Person      ABO group      MN series     Rhesus factor
Husband         O                  M                Rh+
Lover            AB                MN                Rh-
Wife               A                 N                  Rh+
1st child         O                 MN                Rh+
2nd child        A                  N                 Rh+
3rd child         A                 MN               Rh-

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jerichorayel | College Teacher | (Level 1) Senior Educator

Posted May 30, 2013 at 7:57 AM (Answer #1)

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In this problem, the blood types of the parents are enough to determine who the father of the three children is. Let us do the punnett square to see the possible blood type of the offspring.

Wife: Blood type A 
Genotype: AA or AO

Lover: Blood type AB
Genotype: AB

Husband: Blood type O
Genotype: OO

Wife x Lover

     A     A

A   AA   AA

B   AB   AB

     A     O

A   AA   AO

B   AB   BO

 

Wife x Husband

     A     A

O  AO   AO

O  AO   AO

 

     A     O

O  AO    OO

O  AO    OO

 

Results:

Wife and the Lover will have offspring with blood types A, AB and B.

Wife and her husband will have offspring with blood types A and O.

 

Conclusion:

The Husband is absolutely the father of the first child.

The genotype of the mother should be AO not AA


The second and third child is in question. 

-------------------------------------------------------

We need to use the MN and/or Rh of the second and third child.

Wife: phenotype N; genotype NN

Lover: Phenotype MN; genotype MN

Husband: phenotype M; genotype MM

Wife x Lover

     M     N

N   MN   NN

N   MN   NN

 

Wife x Husband

     M    M

N   MN  MN

N   MN  MN

 

Conclusion:

The Lover is the father of the second child

 

 

Sources:

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