The annotation of has been concealed by its protein-coding pseudogene

Mutations in cause Gaucher disease and are the most important genetic risk factor for Parkinson's disease. However, analysis of transcription at this locus is complicated by its highly homologous pseudogene, . We show that >50% of short RNA-sequencing reads mapping to also map to . Thus, we used long-read RNA sequencing in the human brain, which allowed us to accurately quantify expression from both and . We discovered significant differences in expression compared to short-read data and identify currently unannotated transcripts of both and . These included protein-coding transcripts from both genes that were translated in human brain, but without the known lysosomal function-yet accounting for almost a third of transcription. Analyzing brain-specific cell types using long-read and single-nucleus RNA sequencing revealed region-specific variations in transcript expression. Overall, these findings suggest nonlysosomal roles for and with implications for our understanding of the role of in health and disease.