Wistar Institute researchers have identified a variant in an important tumor suppressor gene found only in Africans and African-Americans that might explain the disparities in the incidence of certain cancers and poor clinical outcomes, including lymphoma, observed among African-descent populations.
The research paper, “An African-specific polymorphism in theTP53 gene impairs p53 tumor suppressor function in a mouse model,” was published in the journal Genes and Development.
Cancer clinical data shows that African-Americans, among patients with commonly diagnosed cancers, have higher death rates and overall worse survival outcomes. As an example, the American Cancer Society lists being an African-American as a risk factor for non-Hodgkin lymphoma. In attempts to explain the higher incidence and lower survival of this ethnic group, researchers have previously focused on the contribution of socioeconomic factors to these statistics, but research has now been looking into possible genetic factors.
The team focused on a gene variant, the S47 variant of p53, a tumor suppressor gene that is mutated in a large number of cancers. The S47 variant exists only in people of African descent, and was never observed in Caucasian populations, occurring in 2 percent of African-Americans and 8 percent of Africans. To study the impact of this gene variant, researchers created a mouse model of S47, observing that spontaneous cancer occurred in 80 percent of these animals. Among the cancer cases, liver cancer, lymphoma, and colorectal cancer were the more common malignancies.
Researchers believe this data suggests the S47 variant may contribute to an increased cancer risk for people of African descent, highlighting the need to further assess its contribution to cancer risk in these populations.
“Validation of these results in humans will require a large population to determine the significance it has on cancer risk among those of African descent,” said senior author Dr. Maureen Murphy. “However, we now have some of the strongest evidence ever obtained for a genetic basis for this disparity and a larger, population-based study is warranted.”