Improving the diagnosis of cobalamin and related defects by genomic analysis, plus functional and structural assessment of novel variants
Brasil, Sandra (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Leal, Fátima (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Vega, Ana (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Navarrete, Rosa (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Ecay, María Jesús (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Desviat, Lourdes R. (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Riera, Casandra (Hospital Universitari Vall d'Hebron. Institut de Recerca)
Padilla Sirera, Natàlia (Hospital Universitari Vall d'Hebron. Institut de Recerca)
de la Cruz, Xavier (Institució Catalana de Recerca i Estudis Avançats)
Couce, Maria Luz (Hospital Clínico Universitario (Santiago de Compostela, Galícia))
Martin-Hernández, Elena (Hospital Universitario 12 de Octubre (Madrid))
Morais, Ana (Hospital Universitario La Paz (Madrid))
Pedrón, Consuelo (Hospital Infantil Universitario Niño Jesús (Madrid))
Peña-Quintana, Luis (Universidad de Las Palmas de Gran Canaria)
Rigoldi, Miriam (Center for Rare Disorders, ASST- Monza, Ospedale San Gerardo)
Specola, Norma (Unidad de Metabolismo Hospital de Niños de La Plata (La Plata, Argentina))
de Almeida, Isabel Tavares (Metabolic Diseases Unit (Lisboa, Portugal))
Vives, Inmaculada (Hospital Universitario Virgen de la Arrixaca (Múrcia))
Yahyaoui, Raquel (Instituto de Investigación Biomédica de Málaga)
Rodríguez-Pombo, Pilar (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Ugarte, Magdalena (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Pérez-Cerdá, Celia (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Merinero, Begoña (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Pérez, Belén (Centro de Investigación Biomédica en Red de Enfermedades Raras)
Universitat Autònoma de Barcelona

Date:	2018
Abstract:	Cellular cobalamin defects are a locus and allelic heterogeneous disorder. The gold standard for coming to genetic diagnoses of cobalamin defects has for some time been gene-by-gene Sanger sequencing of individual DNA fragments. Enzymatic and cellular methods are employed before such sequencing to help in the selection of the gene defects to be sought, but this is time-consuming and laborious. Furthermore some cases remain undiagnosed because no biochemical methods have been available to test for cobalamin absorption and transport defects. This paper reports the use of massive parallel sequencing of DNA (exome analysis) for the accurate and rapid genetic diagnosis of cobalamin-related defects in a cohort of affected patients. The method was first validated in an initial cohort with different cobalamin defects. Mendelian segregation, the frequency of mutations, and the comprehensive structural and functional analysis of gene variants, identified disease-causing mutations in 12 genes involved in the absorption and synthesis of active cofactors of vitamin B (22 cases), and in the non-cobalamin metabolism-related genes ACSF3 (in four biochemically misdiagnosed patients) and SUCLA2 (in one patient with an unusual presentation). We have identified thirteen new variants all classified as pathogenic according to the ACGM recommendation but four were classified as variant likely pathogenic in MUT and SUCLA2. Functional and structural analysis provided evidences to classify them as pathogenic variants. The present findings suggest that the technology used is sufficiently sensitive and specific, and the results it provides sufficiently reproducible, to recommend its use as a second-tier test after the biochemical detection of cobalamin disorder markers in the first days of life. However, for accurate diagnoses to be made, biochemical and functional tests that allow comprehensive clinical phenotyping are also needed. The online version of this article (10. 1186/s13023-018-0862-y) contains supplementary material, which is available to authorized users.
Grants:	Instituto de Salud Carlos III PI13-01239 Instituto de Salud Carlos III PI16-00573
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Cobalamin disorders ; Methylmalonic aciduria ; Homocystinuria ; Massive parallel sequencing
Published in:	Orphanet Journal of Rare Diseases, Vol. 13 (july 2018) , ISSN 1750-1172

DOI: 10.1186/s13023-018-0862-y
PMID: 30041674

12 p, 2.0 MB

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