Affiliations: 1) San Francisco State University; 2) Brown University; 3) University of California San Francisco
Keywords: Other (forensic genetics)
The FBI’s Combined DNA index system (CODIS) contains the genetic profiles of over twenty million people. These profiles are composed of Short Tandem Repeats (STRs) located within non-coding DNA – selected under the stipulation that they did not reveal medical information. However, thirteen of the twenty STR loci were selected before the human genome was sequenced. Recent studies indicate that variation in short tandem repeats may alter gene expression. While it is unknown if CODIS STRs do so as well, many CODIS STRs are very close to genes. In fact, eleven of the twenty CODIS STRs are intronic and others are extremely close to genes and regulatory elements. These nearby genes are implicated in a range of medical conditions including schizophrenia, depression, Perrault syndrome and MELAS syndrome. In this study, we used publicly available data to investigate the relationship between CODIS STRs and the expression levels of neighboring genes. We find that CODIS STRs resemble the genomic characteristics of published gene expression-modifying STRs. Furthermore, we identify five CODIS STRs as being associated with the expression of proximal genes in lymphoblastoid cell lines. Lastly, we explore possible mechanisms for these associations, identifying one of the loci as a potential causal locus and three loci as being in LD with a causal locus. Our results are consistent with the hypothesis that CODIS profiles may reveal gene expression information, thus bringing to question the practices regarding these data.