Gabriela Pasqualim1, Laura Simon1, Fernanda Sperb-Ludwig2, Maira Graef Burin3, Kristiane Michelin-Tirelli3, Roberto Giugliani4, Ursula Matte1. 1. Post-Graduation Program on Genetics and Molecular Biology, UFRGS, Porto Alegre, RS, Brazil; Gene Therapy Center, Experimental Research Center, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil. 2. Gene Therapy Center, Experimental Research Center, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil. 3. Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil. 4. Post-Graduation Program on Genetics and Molecular Biology, UFRGS, Porto Alegre, RS, Brazil; Gene Therapy Center, Experimental Research Center, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil; Medical Genetics Service, Hospital de Clínicas de Porto Alegre, Porto Alegre, RS, Brazil; Department of Genetics, UFRGS, Porto Alegre, RS, Brazil; INAGEMP, Porto Alegre, RS, Brazil. Electronic address: rgiugliani@hcpa.ufrgs.br.
Abstract
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.
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.
Authors: Zhe-Yi Dong; Qian Wang; Shu-Peng Lin; Pu Chen; Jiao-Na Liu; Shu-Wen Liu; Guang-Yan Cai; Xiang-Mei Chen; Quan Hong Journal: Ann Transl Med Date: 2020-07
Authors: Roberto Giugliani; Filippo P Vairo; Mariluce Riegel; Carolina F M de Souza; Ida V D Schwartz; Sérgio D J Pena Journal: Orphanet J Rare Dis Date: 2016-06-10 Impact factor: 4.123