Guidelines for diagnosis and management of the cobalamin-related remethylation disorders cblC, cblD, cblE, cblF, cblG, cblJ and MTHFR deficiency.
Huemer MDivision of Metabolism and Children's Research Center, University Childrens' Hospital Zürich, Zurich, Switzerland.
Diodato DDivision of Metabolism, Bambino Gesù Children's Research Hospital, Rome, Italy.
Schwahn BWillink Biochemical Genetics Unit, Saint Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, M13 9WL, UK.
Schiff MReference Center for Inborn Errors of Metabolism, Robert Debré University Hospital, APHP, Paris, France.
Bandeira AMetabolic Unit, Centro Hospitalar do Porto, Porto, Portugal.
Benoist JFReference Center for Inborn Errors of Metabolism, Robert Debré University Hospital, APHP, Paris, France.
Burlina ADivision of Inherited Metabolic Diseases, Department of Pediatrics, University Hospital Padova, Padova, Italy.
Cerone RUniversity Dept of Pediatrics, Giannina Gaslini Institute, Genoa, Italy.
Couce MLCongenital Metabolic Diseases Unit, Hospital Clínico Universitario de Santiago de Compostela, IDIS, CIBER, Compostela, Spain.
Garcia-Cazorla ADepartment of Neurology, Neurometabolism Unit, and CIBERER (ISCIII), Hospital Sant Joan de Deu, Barcelona, Spain.
la Marca GDepartment of Experimental and Clinical Biomedical Sciences, University of Florence, Firence, Italy.
Pasquini EMetabolic and Newborn Screening Clinical Unit, Department of Neurosciences, A. Meyer Children's University Hospital, Florence, Italy.
Vilarinho LNewborn Screening, Metabolism & Genetics Unit, National Institute of Health, Porto, Portugal.
Weisfeld-Adams JDSection of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO, USA.
Kožich VInstitute of Inherited Metabolic Disorders, Charles University-First Faculty of Medicine and General University Hospital, Prague, Czech Republic.
Blom HLaboratory of Clinical Biochemistry and Metabolism, Center for Pediatrics and Adolescent Medicine University Hospital, Freiburg, Freiburg, Germany.
Baumgartner MRDivision of Metabolism and Children's Research Center, University Childrens' Hospital Zürich, Zurich, Switzerland. matthias.baumgartner@kispi.uzh.ch.
Dionisi-Vici CDivision of Metabolism, Bambino Gesù Children's Research Hospital, Rome, Italy. carlo.dionisivici@opbg.net.
English
BACKGROUND Remethylation defects are rare inherited disorders in which impaired remethylation of homocysteine to methionine leads to accumulation of homocysteine and perturbation of numerous methylation reactions.
OBJECTIVE To summarise clinical and biochemical characteristics of these severe disorders and to provide guidelines on diagnosis and management.
DATA SOURCES Review, evaluation and discussion of the medical literature (Medline, Cochrane databases) by a panel of experts on these rare diseases following the GRADE approach.
KEY RECOMMENDATIONS We strongly recommend measuring plasma total homocysteine in any patient presenting with the combination of neurological and/or visual and/or haematological symptoms, subacute spinal cord degeneration, atypical haemolytic uraemic syndrome or unexplained vascular thrombosis. We strongly recommend to initiate treatment with parenteral hydroxocobalamin without delay in any suspected remethylation disorder; it significantly improves survival and incidence of severe complications. We strongly recommend betaine treatment in individuals with MTHFR deficiency; it improves the outcome and prevents disease when given early.