What is the mechanism by which a dominant mutation in the EPO gene increases erythrocyte production?

• A. The mutant EPO allele increases circulating erythrocytes
• B. The mutant EPO allele decreases affinity for EPOR
• C. The mutant EPO allele produces a protein with increased affinity for EPOR
• D. The mutant EPO allele alters erythrocyte morphology

Answer: (C)

The mechanism by which a dominant mutation in the EPO gene increases erythrocyte production involves the production of an EPO protein that has an increased affinity for its receptor, the erythropoietin receptor (EPOR). EPO is a hormone that stimulates the production of red blood cells (erythrocytes) primarily in the bone marrow.

When the mutant EPO allele produces a protein with increased affinity for EPOR, it means that even low concentrations of this mutant EPO can more effectively bind to its receptor. This enhanced binding leads to a more robust activation of the signaling pathways responsible for erythrocyte production. As a result, the bone marrow becomes more responsive to EPO and can produce more erythrocytes. This mechanism explains how the dominant mutation can result in increased erythrocyte production without the need for increased EPO levels in circulation.

Understanding this pathway allows insight into how genetic mutations can lead to physiological changes, such as in conditions related to erythrocyte production, which can be crucial for both understanding certain diseases and developing targeted therapies.