Human erythroid porphobilinogen deaminase exists in 2 splice variants.

Human porphobilinogen deaminase (PBGD) is, reportedly, encoded by 2 distinct messenger RNAs (mRNAs) transcribing from a single gene. The ubiquitous form of the PBGD gene product is often used as an endogenous reference in gene expression studies because it is pseudogene free and has minimal transcriptional variability among tissues. A distinct erythroid-specific gene product has also been described because of the alternate splicing of the gene. Here is reported the existence of an additional erythroid-specific isoform of PBGD mRNA in primary cells.