In the context of hematology, what does G-6-PD deficiency primarily affect?

G-6-PD deficiency primarily affects red blood cell integrity under oxidative stress. This enzyme, glucose-6-phosphate dehydrogenase, is crucial for the pentose phosphate pathway, which helps to protect red blood cells from oxidative damage. When there is a deficiency of G-6-PD, red blood cells become more vulnerable to oxidative agents such as certain medications, infections, or foods like fava beans. This vulnerability can lead to hemolytic anemia, particularly after exposure to these stressors, as the red blood cells break down more easily than normal. Thus, the lack of sufficient G-6-PD compromises the red blood cells' ability to maintain their structural integrity when faced with oxidative threats.