What about the Rh factor?

The Rh factor

        The Rh factor genetic information is also inherited from our parents, but it is inherited independently of the ABO blood type alleles. There are 2 different alleles for the Rh factor known as Rh+ and Rh-.

        Someone who is "Rh positive" or "Rh+" has at least one Rh+ allele, but could have two. Their genotype could be either Rh+/Rh+ or Rh+/Rh-. Someone who Rh- has a genotype of Rh-/Rh-.

Rh factor	Possible genotypes
Rh+	Rh+/Rh+ Rh+/Rh-
Rh-	Rh-/Rh-

     Just like the ABO alleles, each biological parent donates one of their two Rh alleles to their child

     A mother who is Rh- can only pass an Rh- allele to her son or daughter. A father who is Rh+ could pass either an Rh+ or Rh- allele to his son or daughter. This couple could have Rh+ children (Rh- from mother and Rh+ from father) or Rh- children (Rh- from mother and Rh- from father).

Mother	Father	Child
Rh-	Rh+	Rh+
Rh-	Rh-	Rh-

Blood Types

Blood Types Tutorial

The Human ABO markers: The A, B, and O alleles

Human blood type is determined by co-dominant alleles. An allele is one of several different forms of geneticinformation that is present in our DNA at a specific location on a specific chromosome.

Blood Types

    There are three different alleles for human blood type

Blood types	For simplicity, we call these
IA	A
IB	B
i	O

Genotypes

      Each of us has two ABO blood type alleles, because we each inherit one blood type allele from our biological mother and one from our biological father. A description of the pair of alleles in our DNA is called the genotype.

      Since there are three different alleles, there are a total of six different genotypes at the human ABO genetic locus.

Allele from Parent 1	Allele from Parent 2	Genotype of offspring	Blood types of offspring
A	A	AA	A
A	B	AB*	AB
A	O	AO	A
B	A	AB*	AB
B	B	BB	B
B	O	BO	B
O	O	OO	O