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Methylmalonic acidaemia: Examination of genotype and biochemical data in 32 patients belonging to mut, cblA or cblB complementation group
Author(s) -
Merinero B.,
Pérez B.,
PérezCerdá C.,
Rincón A.,
Desviat L. R.,
Martínez M. A.,
Sala P. Ruiz,
García M. J.,
AldamizEchevarría L.,
Campos J.,
Cornejo V.,
Toro M.,
Mahfoud A.,
MartínezPardo M.,
Parini R.,
Pedrón C.,
PeñaQuintana L.,
Pérez M.,
Pourfarzam M.,
Ugarte M.
Publication year - 2008
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/s10545-007-0667-y
Subject(s) - adenosylcobalamin , complementation , genotype , methylmalonic acid , hydroxocobalamin , missense mutation , methylmalonic acidemia , nonsense mutation , genetics , microbiology and biotechnology , biology , mutant , mutase , gene , biochemistry , chemistry , phenotype , vitamin b12 , endocrinology , cyanocobalamin , enzyme , cofactor
Summary Methylmalonic acidaemia (MMA) is a genetic disorder caused by defects in methylmalonyl‐CoA mutase or in any of the different proteins involved in the synthesis of adenosylcobalamin. The aim of this work was to examine the biochemical and clinical phenotype of 32 MMA patients according to their genotype, and to study the mutant mRNA stability by real‐time PCR analysis. Using cellular and biochemical methods, we classified our patient cohort as having the MMA forms mut ( n = 19), cblA ( n = 9) and cblB ( n = 4). All the mut 0 and some of the cblB patients had the most severe clinical and biochemical manifestations, displaying non‐inducible propionate incorporation in the presence of hydroxocobalamin (OHCbl) in vitro and high plasma odd‐numbered long‐chain fatty acid (OLCFA) concentrations under dietary therapy. In contrast, mut − and cblA patients exhibited a milder phenotype with propionate incorporation enhanced by OHCbl and normal OLCFA levels under dietary therapy. No missense mutations identified in the MUT gene, including mut 0 and mut − changes #Affected mRNA stability. A new sequence variation (c.562G>C) in the MMAA gene was identified. Most of the cblA patients carried premature termination codons (PTC) in both alleles. Interestingly, the transcripts containing the PTC mutations were insensitive to nonsense‐mediated decay (NMD).