Erythropoietin Is a Growth Factor Important for the Generation of Red

Multiple Choice

Erythropoietin is a growth factor important for the generation of red blood cells (RBCs) .In the bone marrow, the cells that will differentiate and proliferate to produce RBCs express a cell surface receptor that is activated by erythropoietin (EpoR) .Eero Antero Mäntyranta from Finland was an Olympic skier who was accused of "blood doping" when drug testing revealed that he had abnormally high numbers of RBCs.However, this was a known condition in his family for many generations.A researcher who was studying this family trait discovered that the phenotype was the result of a deletion mutation in the EPOR gene.Mutant EpoR could not be negatively regulated, which resulted in increased production of RBCs.When it comes to competing in competitive sports, this EPOR _______ mutation has proven _______.

A) gain-of-function; harmful
B) loss-of-function; harmful
C) induced; beneficial
D) loss-of-function; beneficial
E) gain-of-function; beneficial