MicroRNAs (miRNAs) are small, ∼22 nt long noncoding RNAs that usually act as posttranscriptional regulators by binding to the 3′-untranslated regions (UTR) of mRNAs (1,2). The mechanism of miRNA targeting largely depends on a miRNA binding to a complementary target site. Sequence polymorphisms in either miRNAs or their target sites may affect this binding, impacting miRNA function and resulting in significant downstream effects on gene expression and higher-order phenotypes (3–9). miRNA-related polymorphisms, including both single-nucleotide polymorphisms (SNPs) (10–16) and small insertions and deletions (INDELS) (17,18), have been associated with many human diseases, including cancers (10–13,17), diabetes (14,18), Parkinson’s disease (15) and Alzheimer’s disease (16).
