Clinical features of 27 turkish propionic acidemia patients with 12 novel mutations (original) (raw)
Related papers
Molecular genetics and metabolism, 2018
Propionic acidemia (PA) is caused by mutations in the PCCA and PCCB genes, encoding α and β subunits, respectively, of the mitochondrial enzyme propionyl-CoA carboxylase (PCC). Up to date, >200 pathogenic mutations have been identified, mostly missense defects. Genetic analysis in PA patients referred to the laboratory for the past 15 years identified 20 novel variants in the PCCA gene and 14 in the PCCB gene. 21 missense variants were predicted as probably disease-causing by different bioinformatics algorithms. Structural analysis in the available 3D model of the PCC enzyme indicated potential instability for most of them. Functional analysis in a eukaryotic system confirmed the pathogenic effect for the missense variants and for one amino acid deletion, as they all exhibited reduced or null PCC activity and protein levels compared to wild-type constructs. PCCB variants p.E168del, p.Q58P and p.I460T resulted in medium-high protein levels and no activity. Variants p.R230C and p.C...
BMC Medical Genetics, 2020
Background Propionic acidemia (PA) is an autosomal recessive metabolic disorder caused by the deficiency of the mitochondrial protein propionyl-CoA carboxylase (PCC) and is associated with pathogenic variants in either of the two genes PCCA or PCCB. The present study aimed to identify the genetic cause of three Chinese patients with PA. Case presentation Three Chinese PA patients were diagnosed by using gas chromatography-mass spectrometry(GC-MS), tandem mass spectrometry (MS/MS) and molecular diagnostic methods. All patients had onset in the neonatal period. One patient died of infection and metabolic decompensation, and the other two had mild to moderate developmental delay/mental retardation. Mutation analysis of the PCCA gene identified that patient 1 carried the compound heterozygous c.1288C > T(p.R430X) and c.2002G > A(p.G668R), and patient 2 was homozygous for the c.1426C > T(p.R476X) mutation. Mutation analysis of the PCCB gene identified that patient 3 harbored the...
Molecular Genetics and Metabolism Reports, 2019
Propionic acidemia (PA) is an autosomal recessive metabolic disorder. PA is characterized by deficiency of the mitochondrial enzyme propionyl CoA carboxylase (PCC) that results in the accumulation of propionic acid. Alpha and beta subunits of the PCC enzyme are encoded by the PCCA and PCCB genes, respectively. Pathogenic variants in PCCA or PCCB disrupt the function of the PCC enzyme preventing the proper breakdown of certain amino acids and metabolites. To determine the frequency of pathogenic variants in PA in our population, 84 Saudi Arabian patients affected with PA were sequenced for both the PCCA and PCCB genes. We found that variants in PCCA accounted for 81% of our cohort (68 patients), while variants in PCCB only accounted for 19% (16 patients). In total, sixteen different sequence variants were detected in the study, where 7 were found in PCCA and 9 in PCCB. The pathogenic variant (c.425G > A; p.Gly142Asp) in PCCA is the most common cause of PA in our cohort and was found in 59 families (70.2%), followed by the frameshift variant (c.990dupT; p.E331Xfs*1) in PCCB that was found in 7 families (8.3%). The p.Gly142Asp missense variant is likely to be a founder pathogenic variant in patients of Saudi Arabian tribal origin and is associated with a severe phenotype. All variants were inherited in a homozygous state except for one family who was compound heterozygous. A total of 11 novel pathogenic variants were detected in this study thereby increasing the known spectrum of pathogenic variants in the PCCA and PCCB genes.
Propionic acidemia: identification of twenty-four novel mutations in Europe and North America
Molecular Genetics and Metabolism, 2003
Propionic acidemia is an inherited metabolic disease caused by the deficiency of the mitochondrial protein propionyl-CoA carboxylase (PCC), one of the four biotin-dependent enzymes. PCC is a multimeric protein composed of two different a-and b-PCC subunits, nuclearly encoded by the PCCA and PCCB genes, respectively. Mutations in either gene cause the clinically heterogeneous disease propionic acidemia. In this work we describe the mutational analysis of PCCA and PCCB deficient patients from different European countries (Spain, Italy, Belgium, Croatia, and Austria) and from America (mainly USA). We report 24 novel PA mutations, nine affecting the PCCA gene and 15 affecting the PCCB gene. They include six missense mutations, one nonsense mutation, one point exonic mutation affecting splicing, seven splicing mutations affecting splice sequences, and nine short insertions or deletions, only two in-frame. We have found a highly heterogenous spectrum of PCCA mutations, most of the PCCA deficient patients are homozygous carrying a unique genotype. The PCCA mutational spectrum includes a high proportion of short insertions or deletions affecting one nucleotide. In the PCCA mutant alleles analyzed we have also found one single nucleotide change, a novel nonsynonymous SNP. On the other hand, the PCCB deficient patients carry a more reduced spectrum of mutations, 50% of them are missense. This work represents an extensive update of the mutational study of propionic acidemia providing important information about the worldwide distribution of PA mutations and representing another essential part in the study of the phenotypegenotype correlations for the prediction of the metabolic outcome and for the implementation of treatments tailored to each PA patient.
Mutation analysis in 54 propionic acidemia patients
Journal of Inherited Metabolic Disease, 2012
Deficiency of propionyl CoA carboxylase (PCC), a dodecamer of alpha and beta subunits, causes inherited propionic acidemia. We have studied, at the molecular level, PCC in 54 patients from 48 families comprised of 96 independent alleles. These patients of various ethnic back-grounds came from research centers and hospitals in Germany, Austria and Switzerland. The thorough clinical characterization of these patients was described in the accompanying paper (Grünert et al. 2012). In all 54 patients, many of whom originated from consanguineous
Molecular Genetics and Metabolism, 1999
Propionic acidemia is a rare autosomal recessive disorder of intermediary metabolism. It is caused by a deficiency of the mitochondrial enzyme propionyl-CoA carboxylase (PCC, EC 6.4.1.3), a heteropolymeric protein composed of two subunits, ␣ and . PCC requires ATP and biotin as cofactors for the reaction, the latter enzymatically added onto the ␣ subunit. We investigated coding sequence mutations in the ␣ subunit of PCC by analyzing fibroblast RNA from propionic acidemia patients deficient in ␣ subunit function by single-strand conformation polymorphism and direct sequencing. Five missense mutations and one short in-frame deletion were found among different patients. Four mutations were located in the putative biotin carboxylase domain, whereas the two others were within the 67-amino-acid C-terminal domain previously shown to be required to obtain biotinylation of the ␣ subunit. We analyzed fibroblast extracts for the presence of a biotinylated ␣ subunit by Western blot analysis using streptavidin coupled to alkaline phosphatase. Four of five cell lines failed to show a biotinylated ␣ subunit, regardless of the position of the mutations within the coding sequence. Two mutations located in the biotinylation domain were expressed in an Escherichia coli-based system and shown to abolish biotinylation of the domain. The results suggest that most mutations have a severe impact on the stability or the functionality of the ␣ subunit.
Propionic acidemia: mutation update and functional and structural effects of the variant alleles
Molecular Genetics and Metabolism, 2004
Mutations in the PCCA or PCCB genes, encoding both subunits of propionyl-CoA carboxylase, result in propionic acidemia, a life-threatening inborn error of metabolism with autosomal recessive inheritance. To date, 41 mutations in the PCCA gene and 54 in the PCCB gene have been reported, most of them single base substitutions causing amino acid replacements, and a variety of small insertions and deletions and splicing defects. A greater heterogeneity is observed in the PCCA gene, specially in Caucasians, with no prevalent mutations, while in the Japanese population three mutations account for more than half of the alleles studied. For the PCCB gene a limited number of mutations is responsible for the majority of the alleles characterized in both Caucasian and Oriental populations. These two populations show a diVerent mutational spectrum, only sharing some involving CpG dinucleotides probably as recurrent mutational events. Functional characterization of the mutant missense alleles has been accomplished using diVerent prokaryotic and eukaryotic systems, and the structural consequences have been analyzed in the available crystal models. For the PCCA gene, the main molecular eVect of the expressed mutations is related to protein instability, except two mutations in the active site predictably aVecting ATP binding. In the PCCB gene the majority of the analyzed mutations are predicted to alter the active site conformation resulting in diminished activity. A few carboxy-terminal PCCB mutations aVect the interaction between subunits and the assembly with PCCA to form a functional PCC oligomer. The amount of normal transcripts resulting from some PCCA and PCCB splicing mutations has also been analyzed. Overall, the data generated from the expression analysis reveal potential genotype-phenotype correlations for this clinically heterogeneous disorder. 2004 Elsevier Inc. All rights reserved.
The American Journal of Human Genetics, 1998
Propionyl-CoA carboxylase (PCC) is a mitochondrial biotin-dependent enzyme composed of an equal number of a and b subunits. Mutations in the PCCA (a subunit) or PCCB (b subunit) gene can cause the inherited metabolic disease propionic acidemia (PA), which can be life threatening in the neonatal period. Lack of data on the genomic structure of PCCB has been a significant impediment to full characterization of PCCB mutant chromosomes. In this study, we describe the genomic organization of the coding sequence of the human PCCB gene and the characterization of mutations causing PA in a total of 29 unrelated patients-21 from Spain and 8 from Latin America. The implementation of long-distance PCR has allowed us to amplify the regions encompassing the exon/intron boundaries and all the exons. The gene consists of 15 exons of 57-183 bp in size. All splice sites are consistent with the gt/ag rule. The availability of the intron sequences flanking each exon has provided the basis for implementation of screening for mutations in the PCCB gene. A total of 56/58 mutant chromosomes studied have been defined, with a total of 16 different mutations detected. The mutation spectrum includes one insertion/deletion, two insertions, 10 missense mutations, one nonsense mutation, and two splicing defects. Thirteen of these mutations correspond to those not described yet in other populations. The mutation profile found in the chromosomes from the Latin American patients basically resembles that of the Spanish patients.
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 1999
The inherited metabolic disease propionic acidemia (PA) can result from mutations in either of the genes PCCA or PCCB, which encode the K and L subunits, respectively, of the mitochondrial enzyme propionyl CoA-carboxylase. In this work we have analyzed the molecular basis of PCCA gene defects, studying mRNA levels and identifying putative disease causing mutations. A total of 10 different mutations, none predominant, are present in a sample of 24 mutant alleles studied. Five novel mutations are reported here for the first time. A neutral polymorphism and a variant allele present in the general population were also detected. To examine the effect of a point mutation (M348K) involving a highly conserved residue, we have carried out in vitro expression of normal and mutant PCCA cDNA and analyzed the mitochondrial import and stability of the resulting proteins. Both wild-type and mutant proteins were imported into mitochondria and processed into the mature form with similar efficiency, but the mature mutant M348K protein decayed more rapidly than did the wild-type, indicating a reduced stability, which is probably the disease-causing mechanism. ß 0925-4439 / 99 / $^see front matter ß 1999 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 5 -4 4 3 9 ( 9 9 ) 0 0 0 0 8 -3 * Corresponding
Functional characterization of PCCA mutations causing propionic acidemia
Biochimica et Biophysica Acta (BBA) - Molecular Basis of Disease, 2002
Propionic acidemia (PA, MIM 232000 and 232050) is caused by a deficiency of mitochondrial biotin-dependent propionyl-CoA carboxylase (PCC, EC 6.4.1.3), a heteropolymeric enzyme composed of a and h subunits, which are encoded by the PCCA and PCCB genes, respectively. The PCCA protein (a subunit) is responsible for the formation of carboxybiotin upon hydrolysis of ATP and contains a Cterminal biotin-binding domain and a biotin carboxylase domain, defined by homology with other biotin-dependent carboxylases, some of them characterized structurally. More than 24 mutations have been found in the PCCA gene in patients with PA, among them 14 missense mutations and one in-frame deletion, for which the precise molecular effect is unknown. In this study, we have established the pathogenicity of 11 PCCA mutations (10 missense and an in-frame deletion) by expression studies in deficient fibroblasts and in a cell-free in vitro system, and analyzed the effect of each mutation on PCC activity, protein stability and domain structure. The results show that most mutant proteins show an increased turnover and are functionally deficient, suggesting that the structural alterations they cause are incompatible with normal assembly to produce a stable, functional PCC oligomer. These results are discussed in the context of the genotype -phenotype correlations in PCCA-deficient PA patients. D