Transfer-RNA-derived fragments (tRFs) are a relatively recently discovered class of non-coding RNAs derived from both precursor and mature transfer RNAs (tRNAs). Research on these molecules has been expanding rapidly, revealing their diverse roles in cellular processes, both in normal physiology and in disease states, often via post-transcriptional regulation of target genes. Altered tRFs abundances have been implicated in various conditions, where they may act as either drivers of disease progression or as protective agents. For instance, specific tRFs are associated with increased risk for cancer metastasis, while others may suppress tumor cell proliferation. Despite the growing recognition of tRFs as functional RNAs rather than sequencing noise, this field of study faces numerous challenges. Inconsistent naming conventions and variability in experimental approaches hinder the comparison of findings across studies, limiting our understanding of the common roles and mechanisms of tRFs. This review provides a comprehensive analysis of current literature on the various roles of tRFs in different diseases, particularly focusing on four broad areas: cancer, neurological, cardiovascular, and musculoskeletal disorders. We analyze studies that link specific tRFs to various aspects of human diseases and provide a convenient classification of these studies regarding the depth of the provided evidence. Further, we note gaps in current investigations and consider strategies to address methodological inconsistencies, including validation experiments and unified nomenclature. By consolidating research in this manner, we aim to facilitate comparisons across diverse studies, enhancing our ability to identify functional commonalities and furthering our understanding of the mechanisms by which tRFs act.
