hemoglobin

The researchers tracked participants' blood pressure, a marker for blood clot and stroke risk; measured hemoglobin levels to check whether the pumps were breaking red blood cells; and monitored patients for other complications.

Part of this is due to changes in the regulation of the EPAS1 gene, which lowers hemoglobin concentrations by regulating the pathway that responds to changing oxygen levels.

This results from either lower than normal levels of red blood cells or a decrease in the quantity or quality of hemoglobin, the protein that allows these cells to transport oxygen.

This is the first time cytoglobin -- or any of the globin proteins like hemoglobin -- has been found to be involved in fetal development and that a paucity could be linked to birth defects.

Sickle cell disease affects hemoglobin, the protein in red blood cells that carries oxygen.