Which condition is characterized by the presence of HbBarts and is typically lethal?

The presence of HbBarts is specifically associated with alpha thalassemia, particularly in its most severe forms. HbBarts is an abnormal hemoglobin that results from the complete absence of alpha globin chains, which leads to the formation of tetramers consisting only of gamma chains. This condition arises in individuals who have a significant or total loss of alpha globin gene function, leading to an ineffective erythropoiesis and severe anemia.

Alpha thalassemia can present in various degrees of severity depending on the number of alpha globin genes that are deleted or mutated. When all four alpha globin genes are affected, the condition is often referred to as alpha thalassemia major, or HbBarts hydrops fetalis, which is usually lethal in utero.

This understanding of HbBarts being correlated with the most severe manifestation of alpha thalassemia highlights why the choice related to alpha thalassemia is the most accurate in this context. Other conditions listed, such as HbH disease or sickle cell disease, while related to hemoglobin abnormalities, do not produce HbBarts and do not share the lethal outcome associated with complete alpha globin gene deletion.