Decoding the ABO Blood Group System: Understanding, Diagnosing, and Utilizing Genetic Testing

Expert Reviewed By: ⁠Dr. Brandon Colby MD

Understanding the ABO Blood Group System

The ABO blood group system is a classification of human blood types based on the presence or absence of specific antigens on the surface of red blood cells. These antigens determine the compatibility of blood transfusions and are also associated with various diseases and conditions. In recent years, studies have shown a potential link between the ABO blood group system and susceptibility to COVID-19, the disease caused by the SARS-CoV-2 virus. By understanding the genetic factors associated with the ABO blood group system, researchers can gain insights into disease susceptibility and potential treatments.

Genetic Components of the ABO Blood Group System

Several genetic factors play a role in determining an individual’s blood type within the ABO blood group system. One such factor is the 3p21.31 gene cluster, which has been associated with comorbidities and COVID-19 [1]. Additionally, the ABO gene, located on chromosome 9, encodes glycosyltransferase enzymes responsible for determining the type of antigens present on red blood cells. The ABO gene has undergone various mutations and polymorphisms throughout human history, as documented in a historical overview of molecular genetic and genomic studies on the ABO blood group system [2].

ABO Blood Group System and COVID-19 Susceptibility

Recent studies have explored the association between blood group types and susceptibility to SARS-CoV-2 infection. A retrospective case-control study from the Middle East and North Africa found a potential link between specific blood group types and the severity of COVID-19 [3]. Furthermore, a study investigating genetic factors associated with the onset and severity of COVID-19 in the Japanese population focused on the IL17A/IL17F gene and the ABO blood group system [4]. These findings suggest that the ABO blood group system may play a role in determining an individual’s susceptibility to COVID-19.

Diagnosing the ABO Blood Group System

Identifying an individual’s blood type within the ABO blood group system is essential for ensuring compatibility during blood transfusions and understanding disease susceptibility. Blood typing is typically performed using serological methods, which involve mixing a blood sample with antibodies specific to A and B antigens. The presence or absence of agglutination (clumping) indicates the blood type. Molecular genetic testing can also be used to identify an individual’s ABO blood group by analyzing the ABO gene.

Uses of Genetic Testing for the ABO Blood Group System

Genetic testing for the ABO blood group system can provide valuable information for various purposes, including:

• Compatibility in blood transfusions: Accurate blood typing is crucial for ensuring the safety and efficacy of blood transfusions. Genetic testing can help identify potential donors and recipients with compatible blood types.
• Disease susceptibility: As research continues to uncover associations between the ABO blood group system and various diseases, including COVID-19, genetic testing can help identify individuals who may be at higher risk for specific conditions.
• Population studies: Understanding the distribution of ABO blood group types within populations can provide insights into human evolution, migration patterns, and disease prevalence.
• Forensic investigations: In some cases, blood group typing can be used as a tool in forensic investigations to help identify individuals involved in a crime.

In conclusion, the ABO blood group system plays a significant role in human health and disease susceptibility. Through genetic testing, researchers and healthcare providers can better understand the role of the ABO blood group system in disease development and inform potential treatments and preventative measures.

About The Expert Reviewer

Dr. Brandon Colby MD is a US physician specializing in the personalized prevention of disease through the use of genomic technologies. He’s an expert in genetic testing, genetic analysis, and precision medicine. Dr. Colby is also the Founder of  and the author of ⁠⁠Outsmart Your Genes.

Dr. Colby holds an MD from the Mount Sinai School of Medicine, an MBA from Stanford University’s Graduate School of Business, and a degree in Genetics with Honors from the University of Michigan. He is an Affiliate Specialist of the American College of Medical Genetics and Genomics (⁠⁠ACMG), an Associate of the American College of Preventive Medicine (⁠⁠ACPM), and a member of the National Society of Genetic Counselors (⁠NSGC)