This locus represents naturally occurring readthrough transcription between the neighboring Slc10a3 (solute carrier family 10 (sodium/bile acid cotransporter family), member 3) and Ubl4 (ubiquitin-like 4) genes on chromosome X. While some readthrough transcripts encode a protein that is identical to the downstream gene product, at least one readthrough transcript appears to be a candidate for nonsense-mediated mRNA decay (NMD), and is unlikely to produce a protein product. [provided by RefSeq, May 2013]