RT Journal Article
T1 Improving the diagnosis of cobalamin and related defects by genomic analysis, plus functional and structural assessment of novel variants.
A1 Brasil, Sandra
A1 Leal, Fátima
A1 Vega, Ana
A1 Navarrete, Rosa
A1 Ecay, María Jesús
A1 Desviat, Lourdes R
A1 Riera, Casandra
A1 Padilla, Natàlia
A1 de la Cruz, Xavier
A1 Couce, Mari Luz
A1 Martin-Hernández, Elena
A1 Morais, Ana
A1 Pedrón, Consuelo
A1 Peña-Quintana, Luis
A1 Rigoldi, Miriam
A1 Specola, Norma
A1 de Almeida, Isabel Tavares
A1 Vives, Inmaculada
A1 Yahyaoui, Raquel
A1 Rodríguez-Pombo, Pilar
A1 Ugarte, Magdalena
A1 Pérez-Cerda, Celia
A1 Merinero, Begoña
A1 Pérez, Belén
K1 Cobalamin disorders
K1 Homocystinuria
K1 Massive parallel sequencing
K1 Methylmalonic aciduria
AB 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 B12 (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.
YR 2018
FD 2018-07-24
LK http://hdl.handle.net/10668/12749
UL http://hdl.handle.net/10668/12749
LA en
DS RISalud
RD Apr 7, 2025