Chapter 4, Problem 9P

Summary Introduction

To analyze:

The ABO, Rhesus (Rh) and MN blood group systems.

Determination of the following aspects from the given information:

a. The genotypes for a child with a blood group – A, Rh^-, M

Woman – O, Rh^-, MN

Man – A, Rh⁺, M.

b. The proportion of children born to a man with genotype I^AI^B Rr MN and woman with I^Ai Rr NN will have blood types B Rh^- MN.

c. Paternity of a child having blood group O Rh- MN with a man having blood group B Rh⁺ N, a woman with A Rh⁺ MN.

Introduction:

A) ABO blood group system- The human blood group system is classified using antigens present on the RBC's (Red blood cells or erythrocyte). ABO blood types were revealed by the Austrian physician Karl Landsteiner (1901). ABO blood group is characterized under multiple alleles that show three or more alternative forms of a gene present on the same locus.

B) Rh blood group system:

Rhesus factor or Rhesus antigen is another isoantigen of RBC. It is the second most blood group system after ABO blood group system. The “Rh” factor is first described in Rhesus monkeys. The expression of Rh factors is denoted in Rh⁺ - expressed (antigen present), Rh^- - deletion of the protein leads to the suppression of antigen (absence of antigen). The Rh factor is crucial during transfusion of blood from a donor to a recipient.

If the donor's Rh factor does not match with that of the recipient, it will lead to a transfusion reaction that causes hemolytic anemia. During pregnancy, Rh factor testing is very essential.

- Rh ⁺ can accept the donation of either Rh⁺ or Rh^-.

- Rh^- can only accept Rh- blood, or it will agglutinate.

C) MN blood group system-

MN blood group is discovered by Landsteiner and Levine. The MN Blood groups genes are closely linked genes present on chromosome 4. The alleles M and N show co-dominance that can have both phenotypes (MM, MN, NN).