Question

Due to the recent death of Gill Bates, noted software "rich guy", lawyers for his estate are searching for a child thought to be his offspring. Only two traits are known about the long-dead mother: she was blood type O and was Rh negative. Rh is a blood antigen produced by a dominant allele (R), whereas the negative phenotype is homozygous recessive (rr). Gill was blood type AB and Rh positive (RR). Several individuals have approached the lawyers claiming to be the "lost heir". After months of investigations, they have reduced the number of possibilities to four people. Since these legal beagles avoided taking Genetics by going to law school (the "easy way out"), they pay you as a consultant to decide this issue. Which of the four individuals is most likely to be Gill Bates' child?

1) Person A
2) Person B
3) Person C
4) Person D

Answer 1

To identify Gill Bates' child, we must look for someone with either type A or B blood with Rh+ or Rh- since Gill was type AB Rh+ and the mother was type O Rh-. Type O is not a possibility in a child from an AB parent, making the individual with type A or B blood and any Rh factor the most probable heir.

Step-by-step explanation:

To determine which individual could potentially be Gill Bates' child, we must consider both the ABO blood types and the Rh factor. The ABO blood type is determined by the presence of antigens on the surface of red blood cells. The alleles involved are:

• IA for the A antigen
• IB for the B antigen
• i for the lack of these antigens (Type O)

Type AB blood indicates the presence of both A and B antigens, hence the genotype must be IAIB.

The Rh factor is determined by the presence (Rh+) or absence (Rh-) of the D antigen. A Rh+ individual can be either homozygous (RR) or heterozygous (Rr) for the Rh factor allele, while an Rh- individual must be homozygous recessive (rr).

Given that Gill Bates was blood type AB Rh+, with a possible genotype of IAIBRR or IAIBRr, and the mother was type O Rh-, with a genotype of ii rr, the child would have to inherit an i allele from the mother and either an IA or IB allele from the father for the ABO blood type. For the Rh factor, the child could be either Rh+ (Rr) or Rh- (rr), given that we do not know Gill Bates' exact Rh genotype.

The child's blood type could only be A or B, either Rh+ or Rh-, since type O is impossible with an AB parent. Therefore, out of the four individuals under consideration, the one with either type A or type B blood, and negative or positive Rh factor is the most likely heir.