GALNS gene expression profiling in Morquio A patients' fibroblasts

BackgroundQuantification studies of mutated mRNAs have not been carried out on Morquio A patients. Such studies are very important for the determination of stability of premature termination codons (PTC) bearing transcripts in order to assess the appropriateness of introducing the newly developed therapeutic strategies such as “stop codon read-through therapy”.MethodsThis paper focuses on the study of the GALNS gene and mRNAs in two severe forms of Morquio A patients' fibroblasts with development of a new and rapid real-time RT-PCR for detection and quantification of absolute mRNA copy number.ResultsWe identified two new mutations c.385A > T (p.K129X) and c.899 − 1G > C) in Pt1 and a known splicing defect c.120 + 1G > A in Pt2. Using RT-PCR and real-time RT-PCR in Pt2 we detected low levels of mRNAs, suggesting its instability; in Pt1, we detected three aberrant mRNAs introducing premature stop codons, suggesting that both the c.385A > T and c.899 − 1G > C mutations produce mRNAs capable of escaping the nonsense-mediated decay (NMD) pathway.ConclusionsThe development of a real-time RT-PCR assay allows to absolutely quantify the GALNS mRNAs carrying mutations that lead to PTCs bearing transcripts, which escape the NMD process and are potentially suitable for the new therapeutic approach.