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Title

Sideroblastic anemia: molecular analysis of the ALAS2 gene in a series of 29 probands and functional studies of 10 missense mutations

Authors
Ducamp, Sarah
Kannengiesser, Caroline
Touati, Mohamed
Garçon, Loïc
Guerci-Bresler, Agnès
Guichard, Jean François
Vermylen, Christiane
Dochir, Joaquim
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Published in Human Mutation. 2011, vol. 32, no. 6, p. 590-7
Abstract X-linked Sideroblastic Anemia (XLSA) is the most common genetic form of sideroblastic anemia, a heterogeneous group of disorders characterized by iron deposits in the mitochondria of erythroid precursors. XLSA is due to mutations in the erythroid-specific 5-aminolevulinate synthase (ALAS2) gene. Thirteen different ALAS2 mutations were identified in 16 out of 29 probands with sideroblastic anemia. One third of the patients were females with a highly skewed X-chromosome inactivation. The identification of seven novel mutations in the ALAS2 gene, six missense mutations, and one deletion in the proximal promoter extends the allelic heterogeneity of XSLA. Most of the missense mutations were predicted to be deleterious, and 10 of them, without any published functional characterization, were expressed in Escherichia coli. ALAS2 activities were assayed in vitro. Five missense mutations resulted in decreased enzymatic activity under standard conditions, and two other mutated proteins had decreased activity when assayed in the absence of exogenous pyridoxal phosphate and increased thermosensitivity. Although most amino acid substitutions result in a clearly decreased enzymatic activity in vitro, a few mutations have a more subtle effect on the protein that is only revealed by in vitro tests under specific conditions.
Keywords 5-Aminolevulinate Synthetase/geneticsAdultAmino Acid SubstitutionAnemiaSideroblastic/geneticsChildFemaleGene ExpressionGenetic DiseasesX-LinkedHeme/biosynthesis/geneticsHumansInfantIron/metabolismMaleMiddle AgedMutationMissenseProtein ConformationProtoporphyrins/geneticsX Chromosome Inactivation
Identifiers
PMID: 21309041
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Article (Published version) (277 Kb) - public document Free access
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Research group Analyses cellulaires et moléculaires des hémopathies malignes (929)
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DUCAMP, Sarah et al. Sideroblastic anemia: molecular analysis of the ALAS2 gene in a series of 29 probands and functional studies of 10 missense mutations. In: Human Mutation, 2011, vol. 32, n° 6, p. 590-7. https://archive-ouverte.unige.ch/unige:100196

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Deposited on : 2017-12-12

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