Basic Population Genetics

Ethnic background influences immune response to TB

Your ethnic background could influence the way in which your body fights tuberculosis. Over the thousands of years that humans have been infected with TB, people of different ethnicities have evolved different immune mechanisms for handling the bacteria, a finding that could affect the outcome of planned trials for new TB drugs.
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Normally such variations in immune response result from differences in the strain of the bacterium causing the infection, says Martineau. But the contrasting changes in markers in the two groups did not relate to the strain of TB involved. They did, however, correlate closely with an individual's genetic variant of a protein that carries vitamin D in the blood, and that is also involved in several immune reactions. This protein varies between ethnic groups. What's more, the differences in immune reactions between Africans and Eurasians in Martineau's study became even more pronounced when they started taking medication for their TB.

Vitamin D production is inversely related to melanin concentration in the skin.   Melanin also has other immune properties.  Varying immune response between differently pigmented populations is what one should expect for most diseases.