Penn Study finds genetic mutations linked with ethnic disparities in cancer

Sept. 10, 2014

One goal of genome sequencing is to identify genetic mutations associated with increased susceptibility to disease. Yet by and large these discoveries have been made in people of European or Asian ancestry, resulting in an incomplete picture of global genetic variation in disease vulnerability.

In a new study published in the journal BMC Medical Genomics, University of Pennsylvania researchers address this omission. Their investigation identifies more than 30 previously undescribed mutations in important regulatory molecules called microRNAs. Many of these mutations influence whether a person develops cancer or the severity of the disease.

One variant has been associated with breast cancer mortality, and the team’s discovery could help explain why, once diagnosed with breast cancer, women with African ancestry are more likely to die from the disease than other women. Knowing about these differences could inform efforts to develop diagnostic tests.

Because miRNAs have the potential to affect a host of genes, scientists are interested in their role in disease. Several miRNAs have been implicated as biomarkers for diseases including diabetes, asthma, and various cancers.

To better understand miRNA diversity, the team searched for miRNA variants in the genome sequences of 69 individuals from 14 populations from Europe, Asia, the Americas, and Africa. The samples included genetic material from diverse African populations. Overall, the researchers found that miRNA sequences were similar across the populations they sampled. Nevertheless, they identified 33 novel variants that appeared in more than one individual and found many that were closely associated with particular populations. Taken as a whole, African groups had more diversity of miRNA expression than the other populations they examined.

The team searched available databases to see which genes these miRNAs were known to inhibit. They turned up a large proportion of genes involved in glucose and insulin metabolism, indicating a possible connection between diabetes risk and possessing one of these variants. The search also pointed to effects on genes involved in cell division, a process that is disrupted in cancers. Read the study.

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