Molecular characterization, by digital PCR analysis of four HMBS gene mutations affecting the ubiquitous isoform of Porphobilinogen Deaminase (PBGD) in patients with Acute Intermittent Porphyria (AIP).

Genetic variants in promoters and alternative-splicing lesions require to be experimentally tested in order to validate them as causatives of a disease. The digital PCR (dPCR) approach, which is an alternative to the classical qPCR, is an innovative and a more sensitive method for the detection and quantification of nucleic acids. In the present study, we identified four HMBS gene mutations affecting the ubiquitous isoform of porphobilinogen deaminase (PBGD) and established a dPCR protocol which would be able to detect the different transcripts of this gene. With the application of this method, we were able to characterize the functional roles of these four genetic variants, demonstrating that all these mutations were causatives of the non-erythroid variant of the acute intermittent porphyria (AIP) disease.