Researchers at the Keck School of Medicine (KSOM) of USC are among the contributors to a large-scale ethnically diverse genetic study that has expanded what we know about potential causes of type 2 diabetes.
The study, a genome-wide meta-analysis, has identified more regions of the genome that are linked to blood glucose and insulin levels, features that contribute to the risk of type 2 diabetes. The findings demonstrate that, while 80-85 percent of genes linked to glucose and insulin levels are the same across different ethnic groups, a significant minority are present in only one or two ethnic groups. Thus, including different multi-ethnic participants yields more and better results. This new approach may ultimately help researchers and health care providers move toward a more precise approach in the diagnosis and management of diabetes in diverse populations.
Making research more diverse
According to the GWAS Diversity Monitor, launched in Nature Genetics in 2020 as a way to track participants included across all published genome-wide association studies in real time, more than 88 percent of research has been conducted in Europeans. This means the results of these studies may not offer the same kind of benefit to people from non-European ancestry as they do people of European descent.
To help rectify this, the MAGIC team analyzed data from 280,000 people without diabetes across a wide range of ethnicities, including individuals of East Asian, Hispanic, African American, South Asian and sub-Saharan African origin. Researchers looked at glycemic traits, which are used to diagnose diabetes and monitor sugar and insulin levels in the blood.
By including multi-ethnic participants, the team discovered 24 more regions of the genome--called loci--that are linked to glycemic traits than if they had conducted the research on Europeans alone.
Research diversity key to precision medicine
Professor Inês Barroso, PhD, of the University of Exeter, who led the research, said,"Type 2 diabetes is an increasingly huge global health challenge--with most of the biggest increases occurring outside of Europe. While there are a lot of shared genetic factors between different countries and cultures, our research tells us that they do differ, in ways that we need to understand. It's critical to ensuring we can deliver a precision diabetes medicine approach that optimises treatment and care for everyone."
KSOM's Thomas Buchanan, MD, professor of medicine, Bernard J. Hanley Chair in Medicine, and vice dean for research, and Richard Watanabe, PhD, professor of preventive medicine and associate dean for health and population science programs, provided a large set of samples from Latino participants. Watanabe also plays a leadership role in MAGIC as a member of the steering committee.
"We have known for a very long time that some racial and ethnic groups have particularly high rates of diabetes in our current environment, which has easy access to food with little requirements for physical activity," Buchanan said. "This study begins to shed some light on the possible genetic contributors to racial/ethnic-specific diabetes risk."
"Genetic studies to date have primarily been in populations of northern European ancestry," Watanabe added. "So this study points to key genetic determinants that not only identify similarities across these diverse groups, but also key differences that may exist. These findings are the first step in moving us towards precision-based medicine, which may eventually improve the quality of life for our local Hispanic population from which the samples we contributed were obtained."
About the study
The paper has more than 400 co-authors, representing scores of organizations. The group in charge of the writing includes Ji Chen and Inês Barroso, University of Exeter; Cassandra N. Spracklen, Andrew P. Morris and Karen L. Mohlke, University of North Carolina, Chapel Hill; Gaëlle Marenne and Eleanor Wheeler, Wellcome Sanger Institute; Arushi Varshney and Stephen C.J. Parker, University of Michigan; Laura J. Corbin, University of Bristol; and Claudia Langenberg, University of Cambridge.
About Keck School of Medicine
Founded in 1885, the Keck School of Medicine of USC is one of the nation's leading medical institutions, known for innovative patient care, scientific discovery, education, and community service. Medical and graduate students work closely with world-renowned faculty and receive hands-on training in one of the nation's most diverse communities. They participate in cutting-edge research as they develop into tomorrow's health leaders. With more than 900 resident physicians across 50 specialty and subspecialty programs, the Keck School is the largest educator of physicians practicing in Southern California.