Why are there miRNA genes on both strands at the same location?


Most of the VectorBase miRNA genes are predicted computationally, by aligning Rfam covariance models against the genome. Some miRNA genes, as a consequence of the miRNA's secondary structure, have symmetrical properties that generate credible alignments on both strands. In the absence of further evidence, we display both as separate genes; it is most likely that only one is correct, but we have no way of discerning which.

The description of such miRNA genes contains the following text: "NOTE: The automated annotation of this gene could not determine the strand, so a version exists on both strands."