Unbalanced GLA mRNAs ratio quantified by real-time PCR in Fabry patients' fibroblasts results in Fabry disease.

Total or partial deficiency of the human lysosomal hydrolase alpha-galactosidase A is responsible for Fabry disease, the X-linked inborn error of glycosphingolipid metabolism. Together with the predominant alpha-galactosidase A gene mRNA product encoding the lysosomal enzyme, a weakly regulated alternatively spliced alpha-galactosidase A transcript is expressed in normal tissues, but its overexpression, due to the intronic g.9331G>A mutation, leads to the cardiac variant. We report the molecular characterization of five Fabry patients including two siblings. Sequencing analysis of the alpha-galactosidase A gene coding region and intron/exon boundaries identified the new c.124A>G (p.M42V) genetic lesion as well as a known deletion in three patients, whereas in the two remaining patients, no mutations were identified. To evaluate possible alpha-galactosidase A gene transcription alterations, both predominant and alternatively spliced mRNAs were quantified by absolute real-time PCR on total RNA preparations from the patients' fibroblasts. An impressive reduction in the predominant alpha-galactosidase A transcript was detected in the last patients (Pt 4 and Pt 5). However, the alternatively spliced mRNA was dramatically overexpressed in one of them, carrying a new intronic lesion (g.9273C>T). These findings strongly suggest a correlation between this new intronic mutation and the unbalanced alpha-galactosidase A mRNAs ratio, which could therefore be responsible for the reduced enzyme activity causing Fabry disease. The real-time assay developed here to investigate the two alpha-galactosidase A mRNAs might play a crucial role in revealing possible genetic lesions and in confirming the pathogenetic mechanisms underlying Fabry disease.

Agalsidase therapy in patients with Fabry disease on renal replacement therapy: a nationwide study in Italy.

BACKGROUND: In Fabry disease, end-stage renal disease (ESRD) and severe neurologic and cardiac complications represent the leading causes of late morbidity and mortality. A comprehensive Italian nationwide survey study was conducted to explore changes in cardiac status and renal allograft function in Fabry patients on renal replacement therapy (RRT) and enzyme replacement therapy (ERT). METHODS: This study was designed as a cross-sectional survey study with prospective follow-up. Of the 34 patients identified via searches in registries, 31 males and 2 females who received RRT and ERT (agalsidase beta in 30 patients, agalsidase alpha in 3) were included. Left ventricular mass index (LVMI), interventricular septal thickness at end diastole (IVSD), left ventricular posterior wall thickness (LVPWT) and renal allograft function were assessed at ERT baseline and subsequently at yearly intervals. RESULTS: The patients in the dialysis and transplant groups had been started on dialysis at age 42.0 and 37.1 years (mean), respectively, and patients in the transplant group received their renal allograft at age 39.8 years (mean). The mean age at the start of ERT was similar, 44.1 and 44.6 years, respectively. The mean RRT follow-up was 61.1 and 110.6 months for dialysis and transplant patients, respectively, whereas the ERT duration was 45.1 and 48.4 months, respectively. Cardiac parameters increased in dialysis patients. In transplant patients, mean LVMI seemed to plateau during agalsidase therapy at a lower level as compared to baseline. Decline in renal allograft function was relatively mild (-1.92 ml/min/year). Agalsidase therapy was well tolerated. Serious ERT-unrelated events occurred more often in the dialysis group. CONCLUSIONS: Kidney transplantation should be the standard of care for Fabry patients progressing towards ESRD. Transplanted Fabry patients on ERT may do better than patients remaining on maintenance dialysis. Larger, controlled studies in Fabry patients with ESRD will have to demonstrate if ERT is able to change the trajectory of cardiac disease and can preserve graft renal function.