Difference Between Genotype and Blood Group

Main Difference – Genotype vs Blood Group

Genotype and blood group are two different phenomena that are used to discriminate between different types of humans. The main difference between genotype and blood group is that genotype is the genetic makeup of the cells of humans whereas blood group is the different types of human blood, which are determined by different antigens present on the surface of red blood cells. Based on the type of hemoglobin present in the red blood cells, six genotypes of humans can be identified. These six genotypes are AA, AS, AC, SS, SC, and CC. The determination of the blood group is done based on two grouping systems. They are ABO blood group and RH blood group. Based on the two blood group systems, eight phenotypes of humans blood can be identified as A-Positive, A-Negative, B-Positive, B-Negative, AB-Positive, AB-Negative, O-Positive, and O-Negative. 

Key Areas Covered

1. What is Genotype
      – Definition, Types and Associated Syndromes, Determination
2. What is Blood Group
      – Definition, Types and Associated Genotypes, Determination
3. What are the Similarities Between Genotype and Blood Group
      – Outline of Common Features
4. What is the Difference Between Genotype and Blood Group
      – Comparison of Key Differences

Key Terms: ABO Blood Group, Genotype, Hemoglobin A, Hemoglobin C, Hemoglobin S, Red Blood Cells, RH Blood Group, Thalassemia

What is Genotype

Genotype is the genetic makeup of the cell. The genotype is unique to a person and it can be revealed by personal genome sequencing. The word ‘genotype’ is also used to describe a gene or a set of genes that determine a particular trait of an organism. The six genotypes of humans are AA, AS, AC, SS, SC, and CC. The red blood cells are involved in the determination of the genotype of humans. The red blood cells of humans consist of hemoglobin, which is an iron-containing, oxygen-transport protein. A hemoglobin molecule is composed of two pairs of globin proteins and a heme part. The two pairs of globin proteins is composed of two alpha and two beta globin chains. Any amino acid substitutions that occur in these chains bring different types of hemoglobin. These amino acid substitutions in the globin proteins are classified under thalassemia. The hemoglobin A, S, and C are the three types of hemoglobin and hemoglobin C is rare. Each type of hemoglobin varies by the amino acid present in the sixth position in the globin chain. The type of hemoglobin and the amino acid found in the sixth position of the globin chain is shown in table 1.

Table 1: Type of hemoglobin and the amino acid present in the sixth position

Any individual may have two types of hemoglobin, each type is inherited from each parent. This pairing of hemoglobin types brings the six different genotypes in humans; AA, AS, AC, SS, SC, and CC. The regular, healthy genotype is AA. The genotypes, SS, SC, and CC may produce various signs, symptoms, and syndromes. Since these genotypes are inherited from parents, the partners should be matched in such a way to not to produce these genotypes. The signs and symptoms of each genotype are shown in table 2.

Genotype and their Signs and Symptoms

Figure 1: Normal and sickle cell anemia red blood cells

What is Blood Group

The blood group refers to different types of blood in humans, which are determined by the presence or absence of different types of antigens on the surface of the red blood cells. Due to the presence of different antigens and antibodies in the blood, it is important to determine the blood group prior to blood transfusion. The determination of the blood group is done under two major criteria. They are ABO blood group system and RH blood group system. Therefore, the blood group of a human is represented as a combination of above two blood groups.

ABO Blood Group System

ABO blood group of a human is determined by the presence or absence of the two antigens, antigen A, and antigen on the surface of the red blood cells. The ABO blood group antigens are encoded by gene I and gene I is composed of three alleles. They are I^A, I^B, and i. The gene products of each allele are involved in attaching the blood group antigens onto the surface of the red blood cells. Six genotypes are involved in the determination of the ABO blood group. Four ABO blood group phenotypes can be identified based on these six genotypes. Environmental exposure may induce the production of corresponding antibodies in the serum of each blood group. The phenotypes of ABO blood group, their corresponding genotypes, and corresponding antibodies in the serum are shown in table 3.

 Blood Types and their Genotypes

Figure 2: Antigens present in different blood types

RH Blood Group

The RH blood group is determined by the presence or absence of Rh factor on the surface of the red blood cells. The Rh factor is also called the ‘Rhesus factor’. There are about 49 different antigens that can be considered as the Rh factor. The most significant antigens among them are antigen D, C, E, c, and e. Generally, the presence of antigen D on the red blood cells’ surface is considered as Rh-positive and the absence of the antigen D is considered as the Rh-negative. 

Figure 3: Eight blood types in humans

Similarities Between Genotype and Blood Group

• Genotype and blood group are two different phenomena used to classify humans.
• Both genotype and blood group are determined by the inherited alleles from parents.
• Both genotype and blood group follow simple Mendelian inheritance patterns.
• The red blood cells are involved in the determination of both genotype and blood group of humans.

Difference Between Genotype and Blood Group

Definition

Genotype: The genetic makeup of a cell is referred to as the genotype.

Blood Group: The blood group refers to different types of blood types in humans, which are determined by different antigens present on the surface of the red blood cells.

Phenotypes

Genotype: The six phenotypes in humans are AA, AS, AC, SS, SC, and CC.

Blood Group: The eight phenotypes of the blood group in humans are A-Positive, A-Negative, B-Positive, B-Negative, AB-Positive, AB-Negative, O-Positive, and O-Negative.

Determination

Genotype: The genotype is determined by the amino acid sequence of the hemoglobin in red blood cells.

Blood Group: The blood group is determined by the presence or absence of blood group antigens on the surface of the red blood cells.

 Conclusion

Genotype and blood group are two phenomena used to categorize humans. Genotype is the genetic makeup of a human, which is unique to an individual. Based on the amino acid sequence of the globin protein, six human genotypes can be identified: AA, AS, AC, SS, SC, and CC. Blood group is determined as a collection of two major grouping systems, ABO blood group and RH blood group. Based on those two blood group systems, eight blood phenotypes can be identified as A-Positive, A-Negative, B-Positive, B-Negative, AB-Positive, AB-Negative, O-Positive, and O-Negative. The main difference between genotype and blood group is the criteria used in the classification of humans in each phenomenon.

Reference:

1. Oluseye, Ajayi. “The AS, AC, SC, SS and CC genotype.” Healthematics, 6 Nov. 2014, Available here. Accessed 15 Aug. 2017.
2. Dean, Laura. “The ABO blood group.” Blood Groups and Red Cell Antigens [Internet]., U.S. National Library of Medicine, 1 Jan. 1970, Available here. Accessed 15 Aug. 2017.
3. Dean, Laura. “The Rh blood group.” Blood Groups and Red Cell Antigens [Internet]., U.S. National Library of Medicine, 1 Jan. 1970, Available here. Accessed 15 Aug. 2017.

Image Courtesy:

1. “Risk-Factors-for-Sickle-Cell-Anemia (1)2” By Diana grib – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “ABO blood group diagram” By InvictaHOG – Own work (Public Domain) via Commons Wikimedia
3. “1968457” (Public Domain) via Pixabay