The different gene definitions for LUZP6. In the Ensembl annotation, LUZP6 is only 177 bp long, and it is completely within another gene, MTPN. As a result, all sequence reads originating from LUZP6 are assigned to MTPN instead. In RefGene, LUZP6 and MTPN are derived from the same genomic region, and both encode exactly the same mRNA, though the protein coding sequences are different. Therefore, all reads mapped to this region are equally distributed between these two genes.