Glucose-6-Phosphate Dehydrogenase Deficiency (G6PD) is an enzyme found
in tissues in most individuals. This enzyme reduces the risk of red
blood cells when they are exposed to certain medications. What are
these medications? Why does this enzyme effect people that are
African-American or Kurdish Jewish population more than other
populations? If these individuals are exposed to the above
medications, can it be life-threatening to the individual?

Fava beans.

G6PD is an enzyme used by red blood cells to produce NADPH, a
substance which protects the red cell from oxidative stress.  In
addition to fava beans (which affects the Mediterranean variant), they
are also susceptible to primaquine and some sulfa drugs, some
infections, and other metabolic abnormalities.  When they are
stressed, they undergo hemolysis (rupture of the cell membrane). 
While it could be life threatening, the hemolytic anemia that ensues
is typically mild.  G6PD deficiency is probably more dangerous to
babies, who may develop neonatal jaundice and subsequent kernicterus
(brain damage due to high bilirubin levels).

The reason for the ethnic distribution is thought to be because a
deficiency in G6PD may protect an individual against severe malaria. 
So in the parts of the world with (historically) endemic malaria
(Africa, Mediterranean countries, etc), the gene was preferrably
selected.  That said, there are studies that have not supported this
idea, but most do.

Hope this helps.
Here's a pretty complete list of drugs that can cause hemolysis:
http://www.g6pd.org/g6pd/table2.htm
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