Another way that polymorphisms in UTRs can influence gene expression is through nonsense-mediated decay (NMD) of mRNA. NMD is a safeguard mechanism that prevents cells from generating deleterious truncated proteins. It degrades abnormal mRNAs that contain a premature termination codon (PTC). NMD can also target normal, non-mutant, transcripts thus regulating gene expression and impacting several physiological processes such as cell differentiation, response to stress, neuronal development, and the onset of various diseases.91 Aberrant splicing, long 3′UTR and uORF are some of the mechanisms implicated in NMD activation.92
