Search

Background Fabry disease (FD [MIM: 301500]) is a disorder caused by mutations in the alpha-galactosidase gene (GLA), which presents great allelic heterogeneity. The development of fast screening methods may reduce costs and length of diagnosis, being particularly important for screening programs of high-risk female patients. Therefore, the purpose of this study was to develop a pre-sequencing genetic screening method based on high resolution melting (HRM) analysis. Methods We performed HRM analysis in one hundred and three individuals, 79 females and 24 males, with a total of 27 different variants in 30 different genotypes. We standardized a protocol using EvaGreen, a release-on-demand dye specific for HRM, added to the PCR reaction. Amplification was performed in a conventional real-time system with HRM capability. Results All genotypes in all amplicons were distinguishable from wild type. In most amplicons it was even possible to differentiate each genotype from the others. Conclusion We developed a simple, fast and highly sensitive HRM based protocol that may facilitate genetic screening of FD.

Objective Fabry disease (FD) is a rare X-linked inborn error of metabolism caused by deficient activity of lysosomal α-galactosidase A (α-GAL). Due to random X inactivation, α-GAL activity in heterozygous females ranges from very low to overlapping normal values. Determining this specific range and altering assays cutoffs could become a valuable tool for minimizing the need in DNA sequencing for screening of all potential carriers. Therefore, the aim of this study was to establish the range of enzyme in dried blood spots (DBS), plasma and leukocytes that suggests carrier status for FD. Design and methods α-GAL gene was sequenced in 453 women with clinical suspicion and/or positive family history of FD. This data was compared to the α-GAL activity measured in DBS (dried blood spots) and/or plasma and/or leukocytes. Results About 12% of the samples had pathogenic mutations (c.30_32delG, c.718_719delAA, p.R118C, p.S126G, p.Y152X, p.A156D, p.C202Y, p.N215S, p.P259R, p.D264Y, p.V269M, p.R342Q and p.R356W). When compared to genotype, DBS was the least reliable biochemical test for screening, with very low specificity. Plasma and leukocyte activities presented high AUC in ROC curve analysis, both over 84%. When cutoffs were altered to identify all carriers, leukocyte specificity was higher than that of plasma (35.2% and 27.6%, respectively). Moderated correlation and agreement coefficients were found between them, which reinforces the need for using both data combined. Conclusion A combined approach involving plasma and leukocyte α-GAL activities, with distinct cutoffs for men and women, could represent a more accurate, faster and less expensive tool to screen women for FD in high-risk groups in middle- and low-income countries.