Ethnic differences in disease incidence and efficacy of medications mean that physicians must be vigilant about how they screen for disease and prescribe for each patient. Often, these insights about ethnic differences occur years after “standards” have been set in the medical literature from trials primarily enrolling Caucasian individuals of European or North American descent. A recent study from China identified variation in BRCA1 and BRCA2 breast cancer mutations across a large Chinese population, and raised the question of whether scientists need to develop an entirely new dataset to accurately reflect genetic breast cancer risk in the non-Caucasian population.
Shanmuga Priya Bhaskaran and colleagues at the University of Macau, China, knew that China had more than 2 decades of disparate BRCA studies, and that newer gene-sequencing developments had accelerated the pace of data collection. Each identified patient with a BRCA mutation, after all, represented an instance of gene sequencing or single nucleotide polymorphism (SNP) analysis.
They conducted an in-depth meta-analysis on existing BRCA studies, drawing from studies of ethnic Chinese across China, Singapore, Malaysia, Hong Kong, and Taiwan. They aggregated more than 30,000 patients with breast cancer and more than 1000 healthy controls, cleaning up the data so that variants that had been described in different ways across studies had standardized nomenclature.
The authors found more than a thousand variants, or unique mutations, in the Chinese BRCA gene data. They identified, for the first time, several alterations that appeared to be pathogenic — that is, mutations that are particularly likely to occur in Chinese people that can confer breast cancer risk. The reason, they said, that some BRCA variants can cause disease in any ethnicity and some are just unique to the Chinese is that humans have “an evolutionary history of genetic diversity and environmental adaptation.”
San Ming Wang, PhD, who is the corresponding author on the study, stated the results have relevance for Chinese immigrants in the US and other countries, as well as for the children of those immigrants. “American-Chinese is basically the same as the native Chinese, as germline variation is inherited, not changed after immigration in a few generations or influenced by [a] different environment in a few hundred years.”