Genomic Diversity for Health Equity: My Journey from Colombia to NIMHD

Posted June 22, 2023

By Leonardo Mariño-Ramírez, Ph.D.
Earl Stadtman Investigator
Epidemiology and Genetics Branch
Division of Intramural Research

I was born and raised in Bogotá, a city of seven million people situated on the altiplano (high planes) of the Andes mountain range in the South American country of Colombia. I studied microbiology as an undergraduate at the University of Los Andes and came to the United States on a Fulbright Scholarship to pursue a Ph.D. in biochemistry at Texas A&M University. Later, I started as a postdoc at the NIH’s National Center for Biotechnology Information (NCBI), where I cultivated my passion for bioinformatics and computational genomics. After years of working at NCBI, my work on human genomics eventually took me back to Colombia, an unexpected development that forever changed the trajectory of my career and ultimately brought me to NIMHD.

Colombia is well known among scientists as a global hotspot for biodiversity, think of this as biological diversity, hosting close to 10 percent of the earth’s biodiversity despite making up one percent of its landmass. What is far less well known, but no less important in my estimation, is the fact that Colombia is also a hotspot of human genetic diversity. Colombia is a remarkably diverse and multiethnic society made up of descendants of the original Indigenous inhabitants of the region, Spanish colonizers, and enslaved Africans brought by force to the New World. These three main groups of people have mixed continuously over the centuries, via the process known as mestizaje, to produce a modern, cosmopolitan population that is characterized by high levels of interbreeding. The clear racial boundaries so easily recognized in the U.S. are thoroughly blurred in Colombia. In Colombia, we are all Mestizos, bound up by a common culture, set of values, and a shared sense of destiny.

My own research on Colombian genomes shows that mestizaje is also written in our DNA. Virtually all Colombians have substantial amounts of African, European, and Indigenous genetic ancestry. It was this profound genetic diversity that could be found in the Colombian population, which finally led me to work on health disparities.

Photo Caption: Dr. Leonardo Mariño (4th from left) in December 2022 with scientific colleagues in the Colombian Andes Mountains. From L to R: Andrés Moreno Estrada, Angélica Borbón, Karla Sandoval, Leonardo Mariño, King Jordan, Alejandro Matamoros, Juan Esteban Gallo, Augusto Valderrama.

Over the last decade, it has become increasingly apparent that genomics research is failing on diversity. The so-called “genomics research gap” refers to the fact that the vast majority of human genetics research cohorts are made of participants with European ancestry. This lack of diversity threatens to exacerbate existing health disparities, since results of studies on European ancestry cohorts may not transfer to other ancestry groups, particularly individuals of African descent who already bear a disproportionate burden of morbidity and mortality in the U.S.

Although, I did not set out to work on health disparities, it became apparent to me that our work on genetically diverse Colombian genomes was exactly the kind of research that was needed to ensure that the benefits of the precision medicine revolution can be shared more broadly – among all people, everywhere. I have since become convinced that genomic diversity is a powerful tool that can and must be leveraged in support of health equity. This is the central theme of my research group – to use genetic diversity in support of epidemiological studies of health disparities in complex, common diseases.

Our focus is not limited to genetics, however. We are relentlessly focused on understanding on how genetics, the environment, and interactions between these two classes of exposures, contribute to disparate health outcomes. In particular, we are using genetic ancestry inference as a means to disentangle genetic, social, and environmental risk factors of health disparities. This approach relies on the fact that genetic ancestry is a characteristic of the genome, which can thus be defined independently of the social dimensions of race and ethnicity, thereby allowing us to partition the genetic and environmental variance components of human health within and between population groups. Publications in [PubMed].

* Mestizaje: A Spanish phrase that refers to racial mixing.

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