Decoding the Mystery: Bombay Phenotype, Digenic and the Power of Genetic Testing

Expert Reviewed By: ⁠Dr. Brandon Colby MD

The Bombay phenotype is a rare blood group characterized by the absence of the H antigen, which is present in all other ABO blood types. This unusual trait results in unique challenges in blood transfusion and organ transplantation, as well as a higher risk of certain health conditions. In this article, we will explore the genetic basis of Bombay phenotype, digenic inheritance, and the crucial role of genetic testing in understanding, diagnosing, and managing this rare blood group.

Understanding the Bombay Phenotype

The Bombay phenotype is caused by mutations in the FUT1 and FUT2 genes, which play a vital role in the synthesis of the H antigen. These mutations can result in a complete absence of the H antigen (Bombay phenotype) or a reduced expression of the H antigen (para-Bombay phenotype). The rarity of the Bombay phenotype, combined with the potential for serious complications in transfusions and transplantation, makes it essential to accurately identify and understand this blood group.

Genetic and Mechanistic Evaluation of an Individual with Para-Bombay Phenotype

A recent study investigated the molecular mechanism of a para-Bombay AB phenotype individual with two novel FUT1 gene variants. The findings of this study provide valuable insight into the genetic basis of the para-Bombay phenotype and contribute to our understanding of the complex relationship between genotype and phenotype in this rare blood group.

Diagnosing the Bombay Phenotype

Accurate diagnosis of the Bombay phenotype is critical for ensuring appropriate medical care and avoiding life-threatening complications. Traditional blood typing methods may not be sufficient to identify the Bombay phenotype, as they rely on the presence of the H antigen. Genetic testing, however, can provide a definitive diagnosis by examining the FUT1 and FUT2 genes for mutations.

Incidental Discovery of a Patient with the Bombay Phenotype

A recent case study reported the discovery of a Bombay phenotype patient in a North American hospital. This case highlights the importance of genetic testing in the identification of Bombay and para-Bombay phenotypes, as well as the need for increased awareness and understanding of this rare blood group among healthcare professionals.

Using Genetic Testing for Bombay Phenotype Management

Genetic testing is not only essential for diagnosing the Bombay phenotype but also plays a crucial role in managing the potential health implications associated with this blood group. By identifying the specific genetic mutations responsible for the Bombay phenotype, healthcare providers can develop personalized treatment plans, ensure the appropriate selection of blood and organ donors, and monitor patients for potential health risks.

Analysis of Two Novel Variants of FUT1 Gene in a Chinese Family with Para-Bombay Phenotype

A recent study identified two new FUT1 gene alleles (h508dupT and h787C) associated with para-Bombay phenotype in a Chinese family. These findings underscore the importance of genetic testing in understanding the diverse genetic variations underlying the Bombay phenotype and ensuring the best possible care for individuals with this rare blood group.

Conclusion

The Bombay phenotype is a rare and complex blood group with significant implications for blood transfusion, organ transplantation, and overall health. Genetic testing plays a vital role in understanding, diagnosing, and managing this unique blood group, providing invaluable information on the specific genetic mutations involved and guiding personalized treatment plans. As our understanding of the Bombay phenotype continues to grow, so too will our ability to provide the best possible care for individuals with this rare and fascinating blood group.

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)