Genetics: Ethnicity

Note:  This original manuscript is slightly different from the final published version because of editorial changes.

Ethnicity is a term used for categorizing the highly diverse human populations into more homogeneous distinct ethnic groups, based on their common ancestry and cultural characteristics. An ethnic group is defined as a category of people that, in a larger population, is set apart (to some extent) and bound together (through preferential intermarriage) by common ties of race, language, nationality, or culture. Commonly recognized American ethnic groups include American Indians, Latinos, Chinese, African Americans ("blacks"), Italians, Irish and other European Americans ("whites"), etc. Ethnic classifications are rather arbitrary, they change over time ("today's ethnicities are yesterday's races"), and they are different in different countries. For example, a person of Pakistani origin is considered "black" or "colored" in the United Kingdom, but would be classified as "white" or "Asian" in the United States. Despite obvious limitations, ethnic classification is useful in aging studies because it allows researchers to explore ethnic differences in aging, longevity, and age-related diseases, as well as the possible role of genetic factors in those differences.

Ethnic groups differ significantly in terms of incidence rates and mortality rates from age-related degenerative diseases including different types of cancer. For example, black Americans have three times higher risk of esophageal cancer; doubled risk for multiple myeloma, liver, cervical, and stomach cancer; and 50% higher risk for cancers of the oral cavity and pharynx, larynx, lung, prostate, and pancreas. In contrast, white Americans have higher incidence rates for melanoma, leukemia, lymphoma, and cancers of the endometrium, thyroid, bladder (in males), ovary, testes, and brain, as well as postmenopausal breast cancer (Perera, 1997). These ethnic differences are attributed to interaction between genetic and lifestyle factors, such as genetic susceptibility to carcinogens (different in different ethnic groups) and ethnic variations in exposure to certain pollutants. In the case of Ashkenazi Jews, a specific mutation (185delAG) has been found in this ethnic group that increases 27-fold the risk of early-onset breast cancer in females (one percent of this ethnic group carries the mutation) (Perera, 1997).

Significant ethnic differences are found for apolipoprotein E genetic polymorphisms, which are important determinants of blood lipid levels, atherosclerosis, and longevity. Specifically, the epsilon 4 allele for this apolipoprotein (APOE4) is more prevalent in African-Americans (21%) than in non-Hispanic whites (12%) or Hispanics (14%) (Pablos-Mendez et al., 1997). The frequency of this allele is inversely correlated with human longevity (Castro et al., 1999), and persons with APOE4 have doubled risk of Alzheimer's disease (Havlik et al., 2000).

Sensational reports have often been published in the past in newspapers and magazines claiming an unusually high percentage of centenarians in some exotic ethnic groups, remote geographic areas, and isolated religious communities. The most famous claims of unusual longevity were made for the Vilcabamba population in Ecuador, for Caucasus and Altay remote populations in the former Soviet Union, and for the Old Order Amish religious communities. Later studies found that these claims were either unsubstantiated or even incorrect because of systematic age exaggeration. Thus, the relationship between ethnicity and exceptional longevity remains to be thoroughly studied. It is interesting to note that the highest longevity world records (122 years and 117 years) that were scientifically validated belong to women of French ethnicity (Gavrilov, Gavrilova, 2000).


Castro, Elena,Ogburn, Charles E., Hunt, Kristin E.,Tilvis, Reijo, Louhija, Jukka, Penttinen, Risto, Erkkola, Risto, Panduro, Arturo, Riestra, Roberto, Piussan, Charles, Deeb, Samir S., Wang, Lan, Edland, Steven D., Martin, George M., and Oshima, Junko. "Polymorphisms at the Werner locus: I. Newly identified polymorphisms, ethnic variability of 1367Cy/Arg, and its stability in a population of Finnish centenarians." American Journal of Medical Genetics 82 (1999): 399-403.

Havlik, Richard J., Izmirlian, Grant, Petrovitch, Helen, Ross, G.Webster, Masaki, Kamal, Curb, J. David, Saunders, Ann M., Foley, Dan J., Brock, Dwight, Launer, Lenore J., and White, Lon. "APOE-epsilon4 predicts incident AD in Japanese-American men: the honolulu-asia aging study." Neurology 11 (2000): 1526-1529.

Pablos-Mendez, Ariel, Mayeux, Richard, Ngai, Colleen, Shea, Steven, and Berglund, Lars. "Association of apo E polymorphism with plasma lipid levels in a multiethnic elderly population." Arterioscler Thromb Vasc Biol 17 (1997): 3534-3541.

Perera, Frederica P. "Environment and cancer: who are susceptible?" Science 278 (1997): 1068-1073.

Gavrilov, Leonid A., and Gavrilova, Natalia S. "Validation of exceptional longevity. Book Review." Population and Development Review 26 (2000): 40-41.