The p.T191M mutation of the CBS gene is highly prevalent among homocystinuric patients from Spain, Portugal and South America (vol 51, pg 305, 2007)

Univ Barcelona, Fac Biol, Dept Genet, E-08028 Barcelona, SpainUniv Nacl Cordoba, Ctr Estudio Metab Congenitas, RA-5000 Cordoba, ArgentinaPontificia Univ Javeriana, Inst Genet Humana, Bogota, ColombiaUniv Antioquia, Fac Med, Dept Fisiol & Bioquim, Medellin, ColombiaFdn Estudio Enfermedades Neurometab, Buenos Aires, DF, ArgentinaInst Genet Med Jacinto Magalhaes, Oporto, PortugalUniversidade Federal de São Paulo, EPM, UNIFESP, Dept Pediat, São Paulo, BrazilHosp Ramon & Cajal, Serv Pediat, Unidad Enfermedades Metab, E-28034 Madrid, SpainHosp Univ Materno Infantil, Unidad Gastroenterol & Nutr, Las Palmas Gran Canaria, SpainHosp Infantil La Fe, Unidad Nutr & Metab, Valencia, SpainHosp Clin Univ Santiago, Dept Pediat, Santiago de Compostela, SpainCorp Sanitaria Clin, Inst Bioquim Clin, Barcelona, SpainHosp St Joan Deu, Serv Bioquim, Barcelona, SpainUniversidade Federal de São Paulo, EPM, UNIFESP, Dept Pediat, São Paulo, BrazilWeb of Scienc

A multicentric study to evaluate the use of relative retention times in targeted proteomics

Despite the maturity reached by targeted proteomic strategies, reliable and standardized protocols are urgently needed to enhance reproducibility among different laboratories and analytical platforms, facilitating a more widespread use in biomedical research. To achieve this goal, the use of dimensionless relative retention times (iRT), defined on the basis of peptide standard retention times (RT), has lately emerged as a powerful tool. The robustness, reproducibility and utility of this strategy were examined for the first time in a multicentric setting, involving 28 laboratories that included 24 of the Spanish network of proteomics laboratories (ProteoRed-ISCIII). According to the results obtained in this study, dimensionless retention time values (iRTs) demonstrated to be a useful tool for transferring and sharing peptide retention times across different chromatographic set-ups both intra- and inter-laboratories. iRT values also showed very low variability over long time periods. Furthermore, parallel quantitative analyses showed a high reproducibility despite the variety of experimental strategies used, either MRM (multiple reaction monitoring) or pseudoMRM, and the diversity of analytical platforms employed. BIOLOGICAL SIGNIFICANCE: From the very beginning of proteomics as an analytical science there has been a growing interest in developing standardized methods and experimental procedures in order to ensure the highest quality and reproducibility of the results. In this regard, the recent (2012) introduction of the dimensionless retention time concept has been a significant advance. In our multicentric (28 laboratories) study we explore the usefulness of this concept in the context of a targeted proteomics experiment, demonstrating that dimensionless retention time values is a useful tool for transferring and sharing peptide retention times across different chromatographic set-ups.All laboratories from Spain are members of ProteoRed (Plataforma de Recursos Biomoleculares y Bioinformáticos) and are supported by grant PT13/0001 funded by Instituto de Salud Carlos III (ISCIII) and FEDER.S

Clinical pattern, mutations and in vitro residual activity in 33 patients with severe 5, 10 methylenetetrahydrofolate reductase (MTHFR) deficiency

Background Severe methylenetetrahydrofolate reductase (MTHFR) deficiency is a rare inborn defect disturbing the remethylation of homocysteine to methionine ( Methods Clinical, biochemical and treatment data was obtained from physicians by using a questionnaire. MTHFR activity was measured in primary fibroblasts; genomic DNA was extracted from cultured fibroblasts. Results Thirty-three patients (mean age at follow-up 11.4 years; four deceased; median age at first presentation 5 weeks; 17 females) were included. Patients with very low (1.7-34.8 %) residual enzyme activity had mainly psychiatric symptoms, mental retardation, myelopathy, ataxia and spasticity. Treatment with various combinations of betaine, methionine, folate and cobalamin improved the biochemical and clinical phenotype. During the disease course, patients with very low enzyme activity showed a progression of feeding problems, neurological symptoms, mental retardation, and psychiatric disease while in patients with higher residual enzyme activity, myelopathy, ataxia and spasticity increased. All other symptoms remained stable or improved in both groups upon treatment as did brain imaging in some cases. No clear genotype-phenotype correlation was obvious. Discussion MTHFR deficiency is a severe disease primarily affecting the central nervous system. Age at presentation and clinical pattern are correlated with residual enzyme activity. Treatment alleviates biochemical abnormalities and clinical symptoms partially

A multicentric study to evaluate the use of relative retention times in targeted proteomics

Despite the maturity reached by targeted proteomic strategies, reliable and standardized protocols are urgently needed to enhance reproducibility among different laboratories and analytical platforms, facilitating a more widespread use in biomedical research. To achieve this goal, the use of dimensionless relative retention times (iRT), defined on the basis of peptide standard retention times (RT), has lately emerged as a powerful tool. The robustness, reproducibility and utility of this strategy were examined for the first time in a multicentric setting, involving 28 laboratories that included 24 of the Spanish network of proteomics laboratories (ProteoRed-ISCIII). According to the results obtained in this study, dimensionless retention time values (iRTs) demonstrated to be a useful tool for transferring and sharing peptide retention times across different chromatographic set-ups both intra- and inter-laboratories. iRT values also showed very low variability over long time periods. Furthermore, parallel quantitative analyses showed a high reproducibility despite the variety of experimental strategies used, either MRM (multiple reaction monitoring) or pseudoMRM, and the diversity of analytical platforms employed. [Biological significance]: From the very beginning of proteomics as an analytical science there has been a growing interest in developing standardized methods and experimental procedures in order to ensure the highest quality and reproducibility of the results. In this regard, the recent (2012) introduction of the dimensionless retention time concept has been a significant advance. In our multicentric (28 laboratories) study we explore the usefulness of this concept in the context of a targeted proteomics experiment, demonstrating that dimensionless retention time values is a useful tool for transferring and sharing peptide retention times across different chromatographic set-ups.All laboratories from Spain are members of ProteoRed (Plataforma de Recursos Biomoleculares y Bioinformáticos) and are supported bygrant PT13/0001 funded by Instituto de Salud Carlos III (ISCIII) andFEDERPeer Reviewe

Multi-laboratory experiment PME11 for the standardization of phosphoproteome analysis

Global analysis of protein phosphorylation by mass spectrometry proteomic techniques has emerged in the last decades as a powerful tool in biological and biomedical research. However, there are several factors that make the global study of the phosphoproteome more challenging than measuring non-modified proteins. The low stoichiometry of the phosphorylated species and the need to retrieve residue specific information require particular attention on sample preparation, data acquisition and processing to ensure reproducibility, qualitative and quantitative robustness and ample phosphoproteome coverage in phosphoproteomic workflows. Aiming to investigate the effect of different variables in the performance of proteome wide phosphoprotein analysis protocols, ProteoRed-ISCIII and EuPA launched the Proteomics Multicentric Experiment 11 (PME11). A reference sample consisting of a yeast protein extract spiked in with different amounts of a phosphomix standard (Sigma/Merck) was distributed to 31 laboratories around the globe. Thirty-six datasets from 23 laboratories were analyzed. Our results indicate the suitability of the PME11 reference sample to benchmark and optimize phosphoproteomics strategies, weighing the influence of different factors, as well as to rank intra and inter laboratory performance.Funding: ProteoRed, PRB3 is supported by grant PT17/0019/0001, of the PE I+D+i 2013-2016, funded by ISCIII and ERD