Functional Genomics Studies of Psychiatric Disorders in Individuals of Latin American Populations: A Scoping Review

Abstract

Over the past 15 years, genetic studies of psychiatric disorders have provided important insight into the contribution of both common variants of small effect, as well as rare exonic and copy number variants with large effect sizes. Genome-wide association studies (GWAS) allow us to understand the intricate polygenicity characteristic of many psychiatric disorders. However, a considerable proportion of single nucleotide polymorphisms (SNPs) implicated in these disorders localize to the non-coding regions of the genome. Unraveling the molecular mechanisms that underlie the etiology of psychiatric illnesses requires integration using functional genomics approaches. Functional genomics methods are critical for developing a mechanistic understanding of genetic findings in psychiatric disorders. Unfortunately, most studies on psychiatric genetics have focused on individuals of European ancestry, which limits our understanding to only a portion of the population. This further contributes to the underrepresentation of other groups, including individuals from Latin America, in genomic studies and restricts our biological insight into these disorders in these populations. To address this issue, we performed an advanced scoping review to ascertain the landscape of functional genomics psychiatric research in Latin American populations. After analyzing over 1380 papers using our search terms, 52 original papers were identified considering individuals of Latin American origin in psychiatric functional genomics research. The majority of these focused on schizophrenia (N = 7), bipolar disorder (N = 7), or a combination of various disorders encompassed in one study (N = 6). DNA methylation techniques were predominant (73%), followed by gene expression (17%) and other techniques. Most samples were from Brazilian (55.8%) or Mexican (21.2%) participants, followed by "Hispanic" (15.3%), Colombian (5.8%), and Costa Rican (1.9%). Although new psychiatric and functional genomics research, including work from the Latin American Genomics Consortium, is expanding our understanding of the genetic basis of these disorders, significant gaps remain. Increasing the representation of samples from admixed and diverse ancestral backgrounds-such as Latin Americans-in future functional genomics studies is greatly needed. This will broaden the applicability of emerging research to a more diverse population and improve the potential impact of psychiatric genetics research on future precision medicine applications.

Keywords: ancestry; epigenomics; functional genomics; psychiatric disorders; transcriptomics.