G6pd deficiency is an inherited condition in which the body doesn't have enough of the enzyme glucose-6-phosphate dehydrogenase, or g6pd, which red blood cells (rbcs) function normally. g6pd deficiency is most common in african-american males. many females are carriers. it is known that africa and the mediterranean basin are high-risk areas for the infectious disease malaria. researchers have found evidence that the parasite that causes malaria does not survive well in g6pd-deficient cells. how can you explain this? natural selection favors g6pd deficiency as compared to malaria. genetic drift is responsible for greater occurrence of g6pd deficiency in these regions. somatic mutations lead to g6pd deficiency in malaria-inflicted regions.

Malaria parasites infect a person by entering the bloodstream through mosquito bites. Then it enters in the liver where it multiplies in the liver cells before going back to the bloodstream where it infects and destroys red blood cells. 

Now since people who have G6PD does not have normally-functioning red blood cells because they lack the enzyme glucose 6-phosphate dehydrogenase, it was observed that they have some sort of protection against the malaria parasites. 

According to the studies done, boys have more protection than girls, because the girls only have one affected X chromosome making them partially G6PD deficient. While 2/3 of the boys who were tested get malaria, it does not progress into severe, life-threatening malaria.

However, the exact reason for this still requires further studies and research.
  

It allows water to resist freezing and thawing cycle.