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Thadchanamoorthy V, Dayasiri K. Unexplained Tachypneoa and Severe Metabolic Acidosis in a Three-Month-Old Child: A Rare Presentation of Beta-Ketothiolose Deficiency. Cureus 2022; 14:e21934. [PMID: 35273875 PMCID: PMC8900828 DOI: 10.7759/cureus.21934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2022] [Indexed: 11/05/2022] Open
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Bancel LP, Germain N, Guemann AS, Joncquel Chevalier Curt M, Dessein AF. Abnormal Ketone Bodies in a 22-Month-Old Boy Presenting with Recurrent Vomiting and Metabolic Acidosis. Clin Chem 2019; 65:1460-1462. [DOI: 10.1373/clinchem.2019.306712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/26/2019] [Indexed: 11/06/2022]
Affiliation(s)
- Léo-Paul Bancel
- CHU Lille, Centre de Biologie Pathologie Génétique, UF Métabolisme Général et Maladies Rares, F-59000 Lille, France
| | - Nicolas Germain
- CHU Lille, Centre de Biologie Pathologie Génétique, UF Métabolisme Général et Maladies Rares, F-59000 Lille, France
| | - Anne-Sophie Guemann
- CHU Lille, Centre de Référence des Maladies Héréditaires du Métabolisme, F-59000 Lille, France
| | | | - Anne-Frédérique Dessein
- CHU Lille, Centre de Biologie Pathologie Génétique, UF Métabolisme Général et Maladies Rares, F-59000 Lille, France
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Abdelkreem E, Harijan RK, Yamaguchi S, Wierenga RK, Fukao T. Mutation update on ACAT1 variants associated with mitochondrial acetoacetyl-CoA thiolase (T2) deficiency. Hum Mutat 2019; 40:1641-1663. [PMID: 31268215 PMCID: PMC6790690 DOI: 10.1002/humu.23831] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 05/27/2019] [Accepted: 05/31/2019] [Indexed: 02/05/2023]
Abstract
Mitochondrial acetoacetyl‐CoA thiolase (T2, encoded by the ACAT1 gene) deficiency is an inherited disorder of ketone body and isoleucine metabolism. It typically manifests with episodic ketoacidosis. The presence of isoleucine‐derived metabolites is the key marker for biochemical diagnosis. To date, 105 ACAT1 variants have been reported in 149 T2‐deficient patients. The 56 disease‐associated missense ACAT1 variants have been mapped onto the crystal structure of T2. Almost all these missense variants concern residues that are completely or partially buried in the T2 structure. Such variants are expected to cause T2 deficiency by having lower in vivo T2 activity because of lower folding efficiency and/or stability. Expression and activity data of 30 disease‐associated missense ACAT1 variants have been measured by expressing them in human SV40‐transformed fibroblasts. Only two variants (p.Cys126Ser and p.Tyr219His) appear to have equal stability as wild‐type. For these variants, which are inactive, the side chains point into the active site. In patients with T2 deficiency, the genotype does not correlate with the clinical phenotype but exerts a considerable effect on the biochemical phenotype. This could be related to variable remaining residual T2 activity in vivo and has important clinical implications concerning disease management and newborn screening.
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Affiliation(s)
- Elsayed Abdelkreem
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan.,Department of Pediatrics, Faculty of Medicine, Sohag University, Sohag, Egypt
| | - Rajesh K Harijan
- Department of Biochemistry, Albert Einstein College of Medicine, New York, New York
| | - Seiji Yamaguchi
- Department of Pediatrics, Shimane University School of Medicine, Izumo, Japan
| | | | - Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
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Yang Y, Jiang SH, Liu S, Han XY, Wang Y, Wang LL, Yu B. Two Infants With Beta-Ketothiolase Deficiency Identified by Newborn Screening in China. Front Genet 2019; 10:451. [PMID: 31156707 PMCID: PMC6530354 DOI: 10.3389/fgene.2019.00451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Accepted: 04/30/2019] [Indexed: 11/13/2022] Open
Abstract
Beta-ketothiolase deficiency (BKTD) is an autosomal recessive disease caused by a defect of mitochondrial acetoacetyl-CoA thiolase. Beginning in 2014, we carried out newborn screening by tandem mass spectrometry (MS/MS) followed by next-generation sequencing (NGS) and identified two infants with BKTD among 203,750 newborns born in Jiangsu Province, China. Both infants showed the characteristic chemical abnormalities of BKTD. We used NGS to confirm variants in the ACAT1. Patient 1 had the compound heterozygous variants c.721dupA and c.928G > C. Patient 2 had compound heterozygosity for the c.238+1G > A and c.1163G > T variants. c.721dupA, c.928G > C and c.1163G > T were suspected to be likely pathogenic, whereas c.238+1G > A was determined to be pathogenic. None of the four variants have been reported in the literature. Patient 1 presented with onset of metabolic acidosis and neonatal hypoglycemia 8 days after birth, whereas patient 2 was detected through neonatal disease screening but had no clinical manifestations. These findings contribute to our understanding of the clinical characteristics and genetic basis of BKTD.
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Affiliation(s)
- Yuqi Yang
- Changzhou Maternity and Child Health Care Hospital, Nanjing Medical University, Changzhou, China
| | - Shu hong Jiang
- Changzhou Maternity and Child Health Care Hospital, Nanjing Medical University, Changzhou, China
| | - Shuang Liu
- Lianyungang Maternal and Child Health Hospital, Yangzhou University, Lianyungang, China
| | - Xiao ya Han
- Changzhou Maternity and Child Health Care Hospital, Nanjing Medical University, Changzhou, China
| | - Ying Wang
- Changzhou Maternity and Child Health Care Hospital, Nanjing Medical University, Changzhou, China
| | - Lei lei Wang
- Lianyungang Maternal and Child Health Hospital, Yangzhou University, Lianyungang, China
| | - Bin Yu
- Changzhou Maternity and Child Health Care Hospital, Nanjing Medical University, Changzhou, China
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Fukao T, Sasai H, Aoyama Y, Otsuka H, Ago Y, Matsumoto H, Abdelkreem E. Recent advances in understanding beta-ketothiolase (mitochondrial acetoacetyl-CoA thiolase, T2) deficiency. J Hum Genet 2018; 64:99-111. [PMID: 30393371 DOI: 10.1038/s10038-018-0524-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/18/2018] [Accepted: 10/03/2018] [Indexed: 02/08/2023]
Abstract
Beta-ketothiolase (mitochondrial acetoacetyl-CoA thiolase, T2) deficiency (OMIM #203750, *607809) is an inborn error of metabolism that affects isoleucine catabolism and ketone body metabolism. This disorder is clinically characterized by intermittent ketoacidotic crises under ketogenic stresses. In addition to a previous 26-case series, four series of T2-deficient patients were recently reported from different regions. In these series, most T2-deficient patients developed their first ketoacidotic crises between the ages of 6 months and 3 years. Most patients experienced less than three metabolic crises. Newborn screening (NBS) for T2 deficiency is performed in some countries but some T2-deficient patients have been missed by NBS. Therefore, T2 deficiency should be considered in patients with severe metabolic acidosis, even in regions where NBS for T2 deficiency is performed. Neurological manifestations, especially extrapyramidal manifestations, can occur as sequelae to severe metabolic acidosis; however, this can also occur in patients without any apparent metabolic crisis or before the onset of metabolic crisis.
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Affiliation(s)
- Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, 500-1194, Japan. .,Division of Clinical Genetics, Gifu University Hospital, Gifu, Japan.
| | - Hideo Sasai
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, 500-1194, Japan
| | - Yuka Aoyama
- Department of Biomedical Sciences, College of Life and Health Sciences, Education and Training Center of Medical Technology, Chubu University, Kasugai, Japan
| | - Hiroki Otsuka
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, 500-1194, Japan
| | - Yasuhiko Ago
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, 500-1194, Japan
| | - Hideki Matsumoto
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, 500-1194, Japan
| | - Elsayed Abdelkreem
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, 500-1194, Japan.,Department of Pediatrics, Faculty of Medicine, Sohag University, Sohag, Egypt
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Aoyama Y, Sasai H, Abdelkreem E, Otsuka H, Nakama M, Kumar S, Aroor S, Shukla A, Fukao T. A novel mutation (c.121‑13T>A) in the polypyrimidine tract of the splice acceptor site of intron 2 causes exon 3 skipping in mitochondrial acetoacetyl-CoA thiolase gene. Mol Med Rep 2017; 15:3879-3884. [PMID: 28393214 DOI: 10.3892/mmr.2017.6434] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2016] [Accepted: 03/10/2017] [Indexed: 02/05/2023] Open
Abstract
Mitochondrial acetoacetyl-CoA thiolase (T2) (gene symbol: ACAT1) deficiency is an autosomal recessive disorder affecting isoleucine catabolism and ketone body utilization. In this study, mutational analysis of an Indian T2-deficient patient revealed a homozygous mutation (c.121‑13T>A) located at the polypyrimidine tract of the splice acceptor site of intron 2, and exon 3 skipping was identified by cDNA analysis using cycloheximide. We made three mutant constructs (c.121‑13T>A, T>C, and T>G substitutions) followed by making a wild-type minigene construct that included an ACAT1 segment from exon 2 to 4 for a splicing experiment. The minigene splicing experiment demonstrated that exon 3 skipping was induced not only by c.121‑13T>A mutation, but also by the other two substitutions. It was difficult to predict the effect of these mutations on splicing using in silico tools, as predictions of different tools were inconsistent with each other. The minigene splicing experiment remains the most reliable method to unravel splicing abnormalities.
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Affiliation(s)
- Yuka Aoyama
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
| | - Hideo Sasai
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
| | - Elsayed Abdelkreem
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
| | - Hiroki Otsuka
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
| | - Mina Nakama
- Division of Clinical Genetics, Gifu University Hospital, Gifu 501‑1194, Japan
| | - Sandeep Kumar
- Department of Pediatrics, Kasturba Medical College, Manipal University, Manipal 576104, India
| | - Shrikiran Aroor
- Department of Pediatrics, Kasturba Medical College, Manipal University, Manipal 576104, India
| | - Anju Shukla
- Department of Medical Genetics, Kasturba Medical College, Manipal University, Manipal 576104, India
| | - Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
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Otsuka H, Sasai H, Nakama M, Aoyama Y, Abdelkreem E, Ohnishi H, Konstantopoulou V, Sass JO, Fukao T. Exon 10 skipping in ACAT1 caused by a novel c.949G>A mutation located at an exonic splice enhancer site. Mol Med Rep 2016; 14:4906-4910. [PMID: 27748876 DOI: 10.3892/mmr.2016.5819] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 08/25/2016] [Indexed: 02/05/2023] Open
Abstract
Beta-ketothiolase deficiency, also known as mitochondrial acetoacetyl-CoA thiolase (T2) deficiency, is an autosomal recessive disease caused by mutations in the acetyl‑CoA acetyltransferase 1 (ACAT1) gene. A German T2‑deficient patient that developed a severe ketoacidotic episode at the age of 11 months, was revealed to be a compound heterozygote of a previously reported null mutation, c.472A>G (p.N158D) and a novel mutation, c.949G>A (p.D317N), in ACAT1. The c.949G>A mutation was suspected to cause aberrant splicing as it is located within an exonic splicing enhancer sequence (c. 947CTGACGC) that is a potential binding site for serine/arginine‑rich splicing factor 1. A mutation in this sequence, c.951C>T, results in exon 10 skipping. A minigene construct was synthesized that included exon 9‑truncated intron 9‑exon 10‑truncated intron 10‑exon 11, and the splicing of this minigene revealed that the c.949G>A mutant construct caused exon 10 skipping in a proportion of the transcripts. Furthermore, additional substitution of G for C at the first nucleotide of exon 10 (c.941G>C) abolished the effect of the c.949G>A mutation. Transient expression analysis of the c.949G>A mutant cDNA revealed no residual T2 activity in the mutated D317N enzyme. Therefore, c.949G>A (D317N) is a pathogenic missense mutation, and diminishes the effect of an exonic splicing enhancer and causes exon 10 skipping. The present study demonstrates that a missense mutation, or even a synonymous substitution, may disrupt enzyme function by interference with splicing.
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Affiliation(s)
- Hiroki Otsuka
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
| | - Hideo Sasai
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
| | - Mina Nakama
- Division of Clinical Genetics, Gifu University Hospital, Gifu 501‑1194, Japan
| | - Yuka Aoyama
- Department of Biomedical Sciences, College of Life and Health Sciences, Education and Training Center of Medical Technology, Chubu University, Kasugai 487‑8501, Japan
| | - Elsayed Abdelkreem
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
| | - Hidenori Ohnishi
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
| | | | - Jörn Oliver Sass
- Bioanalytics and Biochemistry, Department of Natural Sciences, University of Applied Sciences, D‑53359 Rheinbach, Germany
| | - Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501‑1194, Japan
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Abdelkreem E, Otsuka H, Sasai H, Aoyama Y, Hori T, Abd El Aal M, Mahmoud S, Fukao T. Beta-Ketothiolase Deficiency. JOURNAL OF INBORN ERRORS OF METABOLISM AND SCREENING 2016. [DOI: 10.1177/2326409816636644] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- Elsayed Abdelkreem
- Department of Pediatrics, Faculty of Medicine, Sohag University, Sohag, Egypt
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Hiroki Otsuka
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Hideo Sasai
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Yuka Aoyama
- Department of Biomedical Sciences, College of Life and Health Sciences, Education and Training Center of Medical Technology, Chubu University, Kasugai, Japan
| | - Tomohiro Hori
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
| | - Mohamed Abd El Aal
- Department of Pediatrics, Faculty of Medicine, Sohag University, Sohag, Egypt
| | - Shaimaa Mahmoud
- Department of Pediatrics, Faculty of Medicine, Sohag University, Sohag, Egypt
| | - Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
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Hori T, Yamaguchi S, Shinkaku H, Horikawa R, Shigematsu Y, Takayanagi M, Fukao T. Inborn errors of ketone body utilization. Pediatr Int 2015; 57:41-8. [PMID: 25559898 DOI: 10.1111/ped.12585] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2014] [Revised: 12/01/2014] [Accepted: 12/15/2014] [Indexed: 11/28/2022]
Abstract
Succinyl-CoA:3-ketoacid CoA transferase (SCOT) deficiency and mitochondrial acetoacetyl-CoA thiolase (beta-ketothiolase or T2) deficiency are classified as autosomal recessive disorders of ketone body utilization characterized by intermittent ketoacidosis. Patients with mutations retaining no residual activity on analysis of expression of mutant cDNA are designated as severe genotype, and patients with at least one mutation retaining significant residual activity, as mild genotype. Permanent ketosis is a pathognomonic characteristic of SCOT-deficient patients with severe genotype. Patients with mild genotype, however, may not have permanent ketosis, although they may develop severe ketoacidotic episodes similar to patients with severe genotype. Permanent ketosis has not been reported in T2 deficiency. In T2-deficient patients with severe genotype, biochemical diagnosis is done on urinary organic acid analysis and blood acylcarnitine analysis to observe characteristic findings during both ketoacidosis and non-episodic conditions. In Japan, however, it was found that T2-deficient patients with mild genotype are common, and typical profiles were not identified on these analyses. Based on a clinical study of ketone body utilization disorders both in Japan and worldwide, we have developed guidelines for disease diagnosis and treatment. These diseases are treatable by avoiding fasting and by providing early infusion of glucose, which enable the patients to grow without sequelae.
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Affiliation(s)
- Tomohiro Hori
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu, Japan
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Fukao T, Mitchell G, Sass JO, Hori T, Orii K, Aoyama Y. Ketone body metabolism and its defects. J Inherit Metab Dis 2014; 37:541-51. [PMID: 24706027 DOI: 10.1007/s10545-014-9704-9] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2014] [Revised: 03/01/2014] [Accepted: 03/10/2014] [Indexed: 12/17/2022]
Abstract
Acetoacetate (AcAc) and 3-hydroxybutyrate (3HB), the two main ketone bodies of humans, are important vectors of energy transport from the liver to extrahepatic tissues, especially during fasting, when glucose supply is low. Blood total ketone body (TKB) levels should be evaluated in the context of clinical history, such as fasting time and ketogenic stresses. Blood TKB should also be evaluated in parallel with blood glucose and free fatty acids (FFA). The FFA/TKB ratio is especially useful for evaluation of ketone body metabolism. Defects in ketogenesis include mitochondrial HMG-CoA synthase (mHS) deficiency and HMG-CoA lyase (HL) deficiency. mHS deficiency should be considered in non-ketotic hypoglycemia if a fatty acid beta-oxidation defect is suspected, but cannot be confirmed. Patients with HL deficiency can develop hypoglycemic crises and neurological symptoms even in adolescents and adults. Succinyl-CoA-3-oxoacid CoA transferase (SCOT) deficiency and beta-ketothiolase (T2) deficiency are two defects in ketolysis. Permanent ketosis is pathognomonic for SCOT deficiency. However, patients with "mild" SCOT mutations may have nonketotic periods. T2-deficient patients with "mild" mutations may have normal blood acylcarnitine profiles even in ketoacidotic crises. T2 deficient patients cannot be detected in a reliable manner by newborn screening using acylcarnitines. We review recent data on clinical presentation, metabolite profiles and the course of these diseases in adults, including in pregnancy.
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Affiliation(s)
- Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, 1-1 Yanagido, Gifu, 501-1194, Japan,
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Shiasi Arani K, Soltani B. First report of 3-oxothiolase deficiency in iran. Int J Endocrinol Metab 2014; 12:e10960. [PMID: 24782902 PMCID: PMC3997948 DOI: 10.5812/ijem.10960] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 05/18/2013] [Accepted: 07/04/2013] [Indexed: 11/16/2022] Open
Abstract
INTRODUCTION Mitochondrial acetoacetyl-CoA thiolase (3-oxothiolase) deficiency is a rare metabolic disorder involving ketone body metabolism characterized by acute attacks of vomiting, acidosis, ketosis, and lethargy along with some laboratory criteria including excessive excretion of 2-methyl-3-hydroxybutyric acid in urine. CASE PRESENTATION This is a case report of 3-oxothiolase deficiency in a young Iranian boy with presentation of intractable vomiting and severe metabolic acidosis following a common cold in six months of age with abundant urinary 2-methyl-3- hydroxybutyric acid. DISCUSSION This is the first Iranian 3-oxothiolase deficiency case report as searched in the literature. Because of the high rate of consanguineous marriages in Iran, physicians should consider the 3-oxothiolase deficiency in the differential diagnosis of any patient with intractable vomiting and severe metabolic acidosis.
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Affiliation(s)
- Kobra Shiasi Arani
- Research Center for Biochemistry and Nutrition in Metabolic Disorders, Kashan University of Medical Sciences, Kashan, IR Iran
- Corresponding author: Kobra Shiasi Arani, Research Center for Biochemistry and Nutrition in Metabolic Disorders, Kashan University of Medical Sciences, Kashan, IR Iran. Tel: +98-3615550026, E-mail:
| | - Babak Soltani
- Research Center for Biochemistry and Nutrition in Metabolic Disorders, Kashan University of Medical Sciences, Kashan, IR Iran
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Cartwright MM, Hajja W, Al-Khatib S, Hazeghazam M, Sreedhar D, Li RN, Wong-McKinstry E, Carlson RW. Toxigenic and Metabolic Causes of Ketosis and Ketoacidotic Syndromes. Crit Care Clin 2012; 28:601-31. [DOI: 10.1016/j.ccc.2012.07.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Fukao T, Horikawa R, Naiki Y, Tanaka T, Takayanagi M, Yamaguchi S, Kondo N. A novel mutation (c.951C>T) in an exonic splicing enhancer results in exon 10 skipping in the human mitochondrial acetoacetyl-CoA thiolase gene. Mol Genet Metab 2010; 100:339-44. [PMID: 20488739 DOI: 10.1016/j.ymgme.2010.03.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Revised: 03/16/2010] [Accepted: 03/16/2010] [Indexed: 12/25/2022]
Abstract
Mitochondrial acetoacetyl-CoA thiolase (T2) deficiency is an inherited disorder affecting isoleucine catabolism and ketone body metabolism. A Japanese female developed a severe ketoacidotic attack at the age of 7 months. Urinary organic acid analysis showed elevated excretion of 2-methyl-3-hydroxybutyrate but not tiglylglycine. She was diagnosed as having T2 deficiency by enzyme assay using fibroblasts. Mutation analysis revealed a compound heterozygote of c.556G>T(D186Y) and c.951C>T(D317D). Since c.951C>T does not cause amino acid change, we performed cDNA analysis and found that exon 10 skipping had occurred in the c.951C>T allele. A computer search using an ESE finder showed that an exonic splicing enhancer sequence, SF2/ASF, was located in CTGA(951)CGC. We hypothesized that the exonic splicing enhancer is necessary for accurate splicing since the first nucleotide of exon 10 is C, which weakens the splice acceptor site of intron 9. We made a mini gene construct including exon 9-truncated intron 9-exon 10-truncated intron 10-exon 11 for a splicing experiment. We also made three mutant constructs which alter the SF2/ASF site (947C>T, 951C>T, 952G>A). An min-gene splicing experiment clearly showed that exon 10 skipping was induced in all three mutant constructs. Moreover, additional substitution of G for C at the first nucleotide of exon 10 resulted in normal splicing in these three mutants. These results confirmed that c.951C>T diminished the effect of the exonic splicing enhancer and caused exon 10 skipping.
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Affiliation(s)
- Toshiyuki Fukao
- Department of Pediatrics, Graduate School of Medicine, Gifu University, Gifu 501-1194, Japan.
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