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Williams M, Menkovic I, Reitnauer P, Gilbert E, Koeberl D, Young SP, Stiles AR. Critical sample collection delayed? Urine organic acid analysis can still save the day! A new case of HMG-CoA synthase deficiency. Mol Genet Metab Rep 2024; 38:101062. [PMID: 38469099 PMCID: PMC10926198 DOI: 10.1016/j.ymgmr.2024.101062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 01/25/2024] [Accepted: 01/26/2024] [Indexed: 03/13/2024] Open
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase (mHS) deficiency is an autosomal recessive disorder of ketone body synthesis caused by biallelic pathogenic variants in HMGCS2. Clinical symptoms are precipitated by prolonged fasting and/or intercurrent illness with onset before the first year of life. Clinically, patients may present with hypo-/ non-ketotic hypoglycemia, metabolic acidosis, hyperammonemia, lethargy, hepatomegaly, and encephalopathy. During periods of decompensation, elevations of 4-hydroxy-6-methyl-2-pyrone (4-HMP), several hydroxylated hexanoic and hexenoic acid species, and medium-chain dicarboxylic acids in the absence of significant ketonuria may be observed in the urine organic acid profile. Abnormalities may also be observed in plasma which includes elevated acetylcarnitine (C2) and 3-hydroxybutyryl/3-hydroxyisobutyryl (C4-OH) carnitine. We report a patient who presented to the ED at 13 months of age with an undetectable point-of-care blood glucose level. Continuous infusion of dextrose-containing intravenous (IV) fluids were required to correct the hypoglycemia and routine chemistries were notable for an anion gap metabolic acidosis, transaminasemia, and elevated creatine kinase and lactate dehydrogenase. Urine and blood ketones were undetectable. Qualitative assessment of urine organic acids collected ∼46 and ∼ 99 h post-admission were significant for mild elevations of 4-HMP and hydroxy-hexanoic and hydroxy-hexenoic acid species with a notable absence of ketones. Previously, biochemical abnormalities in urine have been shown to normalize in as few as 27 h after treatment giving providers a narrow window with which to obtain a critical sample. Direct communication of laboratory findings to the ordering provider guided the molecular testing and assisted in results interpretation to confirm the molecular diagnosis. Our case emphasizes the importance of collecting samples for biochemical analysis even if the critical period has been missed and acute metabolic decompensation seems to be resolved, as residual abnormalities observed in our patient greatly narrowed the differential diagnosis.
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Affiliation(s)
- Monika Williams
- Department of Pediatrics, Division of Pediatric Genetics and Metabolism, UNC, Chapel Hill, NC, USA
| | - Iskren Menkovic
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
| | - Pamela Reitnauer
- Pediatric Teaching Program & Pediatric Medical Genetics, Cone Health, Greensboro, NC, USA
| | - Eileen Gilbert
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
| | - Dwight Koeberl
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Sarah P. Young
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
| | - Ashlee R. Stiles
- Biochemical Genetics Laboratory, Duke University Health System, Durham, NC, USA
- Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA
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Wu S, Shen L, Chen Q, Gong C, Yang Y, Wei H, Cao B, Chen Y. Clinical, Biochemical, Molecular, and Outcome Features of Mitochondrial 3-Hydroxy-3-Methylglutaryl-CoA Synthase Deficiency in 10 Chinese Patients. Front Genet 2022; 12:816779. [PMID: 35308163 PMCID: PMC8931749 DOI: 10.3389/fgene.2021.816779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Accepted: 12/31/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency (HMGCS2D) is a rare autosomal recessive metabolic disorder caused by mutations of the HMGCS2 gene. To date, no more than 60 patients have been reported throughout the world. Purpose: To analyze the clinical, biochemical, molecular, and outcome features of HMGCS2D in a case series of 10 new Chinese patients. Methods: This retrospective study includes 10 Chinese patients diagnosed with HMGCS2D. We collected and analyzed clinical data for all patients. We also reviewed clinical data for 39 cases that had been reported previously. Results: All of our patients had experienced their first metabolic crisis before 12 months old. The most common clinical manifestations were anorexia, dyspnea, and disturbance of consciousness (10/10), followed by vomiting (8/10), fever (7/10), cough (4/10), diarrhea, and seizures (3/10). Each patient (10/10) had a different degree of hepatomegaly and increased aminotransferase, severe metabolic acidosis, and hypofibrinogenemia. 9 patients presented with severe hypoglycemia and weak positives on qualitative tests of urinary ketone body. Patient 3 was the only one without hypoglycemia. Five patients had hypocalcemia, five patients had hyperammonemia, four patients had hyperuricemia, and three had hypertriglyceridemia. During the metabolic acidosis episode, we observed high dicarboxylic acid values in urine, and the elevated ratio of blood acetylcarnitine to free carnitine may have been an additional biochemical signature. However, all returned to normal during the interictal interval. Molecular analysis identified 15 variants in the HMGCS2 gene, of which 10 were novel (c.220G>A/p.E74K, c.407A>G/p.D136G, c.422T>A/p.V141D, c.719A>C/p.D240A, c.821G>A/p.R274H, c.39dupA/p.L14Tfs*59, c.1394delA/p.N465Tfs*10, c.788delT/p.L263Cfs*36, c.717T>G/p.Y239*, and c.1017-2A>G). Combining these with previous cases, the known mutation c.1201G>T/p.E401* has been found in 6/40 (15.0%) of mutated alleles in 21 Chinese patients from 20 families, while none have been found in other populations. We found that patients with biallelic truncation mutation appeared to show a more severe clinical condition through a literature review. Conclusion: This study analyzed the phenotypic and genetic features of HMGCS2D in a Chinese case series. We also expanded the HMGCS2 mutational spectrum with 10 novel variants. The c.1201G>T/p.E401* mutation was the most frequent, representing 15.0% of the mutated alleles in reported unrelated Chinese patients, and thus, it may be a hot spot mutation.
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Affiliation(s)
- Shengnan Wu
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
| | - Linghua Shen
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
| | - Qiong Chen
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
| | - Chunxiu Gong
- Department of Endocrinology, Genetics and Metabolism, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
| | - Yanling Yang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Haiyan Wei
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
| | - Bingyan Cao
- Department of Endocrinology, Genetics and Metabolism, Beijing Children’s Hospital, Capital Medical University, National Center for Children’s Health, Beijing, China
- *Correspondence: Yongxing Chen, ; Bingyan Cao,
| | - Yongxing Chen
- Department of Endocrinology and Metabolism, Henan Key Laboratory of Children’s Genetics and Metabolic Diseases, Children’s Hospital Affiliated to Zhengzhou University, Henan Children’s Hospital, Zhengzhou Children’s Hospital, Zhengzhou, China
- *Correspondence: Yongxing Chen, ; Bingyan Cao,
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3
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Hurst IA, Calhoun A, Mehren R, Held P, Asamoa-Bonsu Y, Cathers A. Metabolic Emergency in Flight. Air Med J 2022; 41:141-146. [PMID: 35248334 DOI: 10.1016/j.amj.2021.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/21/2021] [Indexed: 11/16/2022]
Abstract
Young children with inborn errors of metabolism often present to medical care in extremis, although their symptoms can be nonspecific. Rare metabolic disorders are not always on the statewide newborn screening panels, so infants and children can present later in life with vomiting, altered mental status, seizures, coma, or death, without any indication prior of a metabolic disorder. Swift transport to a pediatric specialty center can be lifesaving and prevent neurologic damage in these patients while awaiting definitive testing for these genetic disorders. Transport of these patients is complicated because they are often critically ill yet do not respond normally to routine resuscitation. In this case, we describe the transport of a patient with a rare, undifferentiated inborn error of metabolism with a pediatric specialty flight team and the considerations made in resuscitation and treatment of this patient in flight.
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Affiliation(s)
- Irene A Hurst
- Department of Emergency Medicine, University of Wisconsin-Madison, Madison, WI; Division of Pediatric Emergency Medicine, University of Wisconsin-Madison, Madison, WI; School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI.
| | - Amy Calhoun
- University of Iowa Stead Family Children's Hospital, Department of Pediatrics, Division of Medical Genetics and Genomics, University of Iowa Healthcare, Iowa City, IA
| | - Ryan Mehren
- UW Med Flight, University of Wisconsin-Madison, Madison, WI
| | - Patrice Held
- School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI; Department of Pediatrics, University of Wisconsin-Madison, Madison, WI; Wisconsin State Laboratory of Hygiene, Madison, WI
| | - Yaw Asamoa-Bonsu
- Department of Pediatrics, University of Wisconsin-Madison, Madison, WI; Division of Pediatric Critical Care, University of Wisconsin-Madison, Madison, WI
| | - Andrew Cathers
- Department of Emergency Medicine, University of Wisconsin-Madison, Madison, WI; School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI; UW Med Flight, University of Wisconsin-Madison, Madison, WI
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Heidari M, Soleyman‐Nejad M, Isazadeh A, Shapouri J, Taskhiri MH, Ahangari R, Mohamadi AR, Ebrahimi M, Karimi H, Bolhassani M, Karimi Z, Heidari M. Association of a novel homozygous mutation in the HMGCS2 gene with an HMGCSD in an Iranian patient. Mol Genet Genomic Med 2020; 8:e1507. [PMID: 32969201 PMCID: PMC7667326 DOI: 10.1002/mgg3.1507] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 05/08/2020] [Accepted: 07/14/2020] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND 3-Hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase 2 gene (HMGCS2) encodes a mitochondrial enzyme catalyzing the first reaction of ketogenesis metabolic pathway which provides lipid-derived energy for various organs during times of carbohydrate deprivation, such as fasting. Mutations in this gene are responsible for HMG-CoA synthase deficiency (HMGCSD). The aim of present study was to investigate the association of mutation in the HMGCS2 gene with HMGCSD in a patient with atypical symptoms. METHODS The clinical and genetic features of an 8-months-old girl with HMGCSD were evaluated. Molecular genetic testing was conducted using whole-exome sequencing (WES) in order to identify potential disease-causing mutation. The WES finding was confirmed by the polymerase chain reaction (PCR) amplification of the target sequence carried out for the patient and her parents. The PCR products were subjected to direct sequencing using forward and reverse specific primers corresponding to the HMGCS2 gene. RESULTS A novel homozygous missense mutation (c.266G>A p.Gly89Asp) was detected in the HMGCS2 gene. Sanger sequencing along with co-segregation analysis of all family members confirmed this novel pathogenic germline mutation. The mutant gene was found to be pathogenic by bioinformatics analysis. CONCLUSION To our best knowledge, this is the first report of HMGCSD in Iran which would expand our knowledge about the mutational spectrum of the HMGCS2 gene and the phenotype variations of the disease.
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Affiliation(s)
- Masoud Heidari
- Department of Animal BiologyFaculty of Natural SciencesUniversity of TabrizTabrizIran
| | | | - Alireza Isazadeh
- Immunology Research CenterTabriz University of Medical SciencesTabrizIran
| | - Javad Shapouri
- Pediatric Clinical Research and Development CenterQom University of Medical SciencesQomIran
| | - Mohammad Hossein Taskhiri
- Ariagene Medical Genetics LaboratoryQomIran
- Department of Cellular and Molecular GeneticsIslamic Azad University, Qom BranchQomIran
| | - Roghayyeh Ahangari
- Department of Obstetrics and GynecologyNekouei‐Hedayati‐Forghani HospitalQom University of Medical SciencesQomIran
| | | | | | - Hadi Karimi
- Qom Social Welfare and Rehabilitation CenterQomIran
| | | | | | - Mansour Heidari
- Ariagene Medical Genetics LaboratoryQomIran
- Department of Medical GeneticsTehran University of Medical Sciences (TUMSTehranIran
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5
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Rojnueangnit K, Maneechai P, Thaweekul P, Piriyanon P, Khositseth S, Ittiwut C, Chetruengchai W, Kamolvisit W, Theerapanon T, Suphapeetiporn K, Porntaveetus T, Shotelersuk V. Expanding phenotypic and mutational spectra of mitochondrial HMG-CoA synthase deficiency. Eur J Med Genet 2020; 63:104086. [PMID: 33045405 DOI: 10.1016/j.ejmg.2020.104086] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Revised: 09/09/2020] [Accepted: 10/04/2020] [Indexed: 11/29/2022]
Abstract
Mitochondrial 3-hydroxy-3 methylglutaryl-CoA synthase-2 deficiency (HMGCS2D) is a rare autosomal recessive inborn error of hepatic ketogenesis, caused by mutations in HMGCS2. As its clinical and laboratory manifestations resemble many other metabolic disorders, HMGCS2D definite diagnosis presents a challenge, frequently requiring molecular tests. Only 26 patients with HMGCS2 mutations have been previously described, and this study reports the first two unrelated Thai patients, a 9-month-old male and an 8-month-old female, with HMGCS2D. During acute episodes, steatorrhea and dyslipidemia occurred, both previously unreported. Increased serum levels of triglycerides, very low density lipoproteins (VLDL), and low density lipoproteins (LDL), along with a decreased serum level of HDL were found. Both patients had hypophosphatemic encephalopathy, and the female had metabolic acidosis without hypoglycemia. Trio whole-exome sequencing (WES) revealed that the male harbored two HMGCS2 mutations, a novel c.1480C>T (p.Arg494*) and a previously reported c.1502G>C (p.Arg501Pro), while the female was compound heterozygous for the c.1502G>C (p.Arg501Pro) and a previously reported mutation, c.520T>C (p.Phe174Leu). Interestingly, c.1502G>C (p.Arg501Pro) was not only found in both of our patients but also detected heterozygously in 9 out of 1081 unrelated individuals (allele frequency of 9/2162; 0.42%) in our in-house Thai exome database. Discovery of this common mutation suggests there could be about 14 babies with HMGCS2D within 800,000 newborns in Thailand annually. Therefore, awareness of HMGCS2D among medical personnel in Thailand should be raised.
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Affiliation(s)
- Kitiwan Rojnueangnit
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Parisa Maneechai
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Patcharapa Thaweekul
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Punnapat Piriyanon
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Sookkasem Khositseth
- Department of Pediatrics, Faculty of Medicine, Thammasat University, Pathumthani, 12120, Thailand
| | - Chupong Ittiwut
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Wanna Chetruengchai
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Wuttichart Kamolvisit
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Thanakorn Theerapanon
- Genomics and Precision Dentistry Research Unit, Department of Physiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand
| | - Kanya Suphapeetiporn
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
| | - Thantrira Porntaveetus
- Genomics and Precision Dentistry Research Unit, Department of Physiology, Faculty of Dentistry, Chulalongkorn University, Bangkok, 10330, Thailand.
| | - Vorasuk Shotelersuk
- Center of Excellence for Medical Genomics, Medical Genomics Cluster, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, 10330, Thailand; Excellence Center for Genomics and Precision Medicine, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, 10330, Thailand
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Conlon TA, Fitzsimons PE, Borovickova I, Kirby F, Murphy S, Knerr I, Crushell E. Hypoglycemia is not a defining feature of metabolic crisis in mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: Further evidence of specific biochemical markers which may aid diagnosis. JIMD Rep 2020; 55:26-31. [PMID: 32905056 PMCID: PMC7463059 DOI: 10.1002/jmd2.12146] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 05/25/2020] [Accepted: 05/27/2020] [Indexed: 11/12/2022] Open
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG Co-A) synthase (mHS) deficiency is an autosomal recessive disorder of ketone body synthesis which has traditionally been associated with hypoketotic hypoglycemia, hepatomegaly and encephalopathy, presenting in early childhood following a period of fasting. We report the third case of mHS deficiency presenting in the absence of hypoglycemia, with profound biochemical abnormalities and further evidence of potential specific diagnostic biomarkers. A previously well, 20-month old, unvaccinated male, of nonconsanguineous Polish heritage, presented with encephalopathy, hepatomegaly, severe metabolic acidosis, and mild hyperammonemia following a brief intercurrent illness. The patient was reported to have taken colloidal silver prior to presentation, posing a further diagnostic challenge. Additionally, he developed features suggestive of hemophagocytic lymphohistiocytosis during treatment. While the patient was normoglycemic prior to dextrose administration, the sample was markedly lipemic, with significant hypertriglyceridemia detected. Urine organic acid analysis revealed dicarboxylic aciduria with 4-hydroxy-6-methyl-2-pyrone (4HMP) and the presence of three other previously reported putative biomarkers for mHS deficiency. Glutarate was markedly elevated in the initial chromatogram, with a mild increase in 3-hydroxyglutarate (3HG) persisting. Raised acetylcarnitine was detected on acylcarnitine profile. Molecular genetic analysis of the HMGCS2 gene identified compound heterozygosity for known pathogenic mutations c.634G>A and c.1016+1G>A, confirming the diagnosis of mHS deficiency. This case provides further evidence that hypoglycemia is not invariably present in symptomatic mHS deficiency. We propose that elevated acetylcarnitine, triglycerides, and 3HG are additional biochemical features during acute presentations. With the expansion of novel biomarkers, further cases of this rare disorder may emerge.
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Affiliation(s)
- Tracey A. Conlon
- National Centre for Inherited Metabolic DisordersChildren's Health Ireland at Temple StreetDublinIreland
- School of MedicineUniversity College DublinDublinIreland
| | - Patricia E. Fitzsimons
- Department of Paediatric Laboratory MedicineChildren's Health Ireland at Temple StreetDublinIreland
| | - Ingrid Borovickova
- Department of Paediatric Laboratory MedicineChildren's Health Ireland at Temple StreetDublinIreland
| | - Fidelma Kirby
- Department of Paediatric Intensive CareChildren's Health Ireland at Temple StreetDublinIreland
| | - Sinéad Murphy
- School of MedicineUniversity College DublinDublinIreland
- Department of General PaediatricsChildren's Health Ireland at Temple StreetDublinIreland
| | - Ina Knerr
- National Centre for Inherited Metabolic DisordersChildren's Health Ireland at Temple StreetDublinIreland
- School of MedicineUniversity College DublinDublinIreland
| | - Ellen Crushell
- National Centre for Inherited Metabolic DisordersChildren's Health Ireland at Temple StreetDublinIreland
- School of MedicineUniversity College DublinDublinIreland
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Clinical, biochemical, molecular and therapeutic characteristics of four new patients of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency. Clin Chim Acta 2020; 509:83-90. [PMID: 32470406 DOI: 10.1016/j.cca.2020.04.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 04/01/2020] [Accepted: 04/04/2020] [Indexed: 11/24/2022]
Abstract
Thirty patients with mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (HMGCS) deficiency, which is a rare autosomal recessive disorder caused by HMGCS2 gene mutation are known. Here, we present four new patients with this disease. The characteristics including several metabolites of patients were recorded. Next-generation targeted sequencing and multiple sequence alignment of PCR amplified products allowed for mutational analysis of HMGCS2. Minigene assay transcript analysis confirmed pathogenicity of a splice site mutation. All cases had recurrent episodes with infections while they had no symptoms during intermissions. Patient 1, a girl, showed recurrent severe metabolic acidosis after infections from 8 months old and presented with weakness, vomiting and lethargy but had normal blood glucose. After treatment, she revived completely. Patients 2, 3 and 4 were boys who showed episodes of hypoglycemia since 8, 27 and 10 months of age, respectively. Glucose infusion reversed the symptoms. All four patients had hepatomegaly and abdominal imaging showed fatty livers. Serum free fatty acid increased. Urinary dicarboxylic acids and urinary 4-hydroxy-6-methyl-2pyrone presented. Diagnosis was confirmed by HMGCS2 gene analysis and 7 mutations (p.R188H, p.F420S, p.R206C, IVS2 + 1G > T, p.E401*, p.A450Pfs*7 and p.Q427*) of this gene were found. Here we report on the characteristics and genetics of four new patients with HMGCS deficiency. This study will enrich our knowledge of this rare autosomal recessive disorder.
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8
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Kılıç M, Dorum S, Topak A, Yazıcı MU, Ezgu FS, Coskun T. Expanding the clinical spectrum of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency with Turkish cases harboring novel HMGCS2 gene mutations and literature review. Am J Med Genet A 2020; 182:1608-1614. [PMID: 32259399 DOI: 10.1002/ajmg.a.61590] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 03/20/2020] [Accepted: 03/24/2020] [Indexed: 11/10/2022]
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (mHS) deficiency is a very rare autosomal recessive inborn error of ketone body synthesis and presents with hypoketotic hypoglycemia, metabolic acidosis, lethargy, encephalopathy, and hepatomegaly with fatty liver precipitated by catabolic stress. We report acute presentation of two patients from unrelated two families with novel homozygous c.862C>T and c.725-2A>C mutations, respectively, in HMGCS2 gene. Affected patients had severe hypoketotic hypoglycemia, lethargy, encephalopathy, severe metabolic and lactic acidosis and hepatomegaly after infections. Surprisingly, molecular screening of the second family showed more affected patients without clinical findings. These cases expand the clinic spectrum of this extremely rare disease.
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Affiliation(s)
- Mustafa Kılıç
- Sami Ulus Children Hospital, Metabolism Unit, Ankara, Turkey
| | - Sevil Dorum
- Department of Pediatrics, Metabolism Unit, Yuksek Ihtisas Training and Research Hospital, Bursa, Turkey
| | - Ali Topak
- Medical Genetic Unit, Yuksek Ihtisas Training and Research Hospital, Bursa, Turkey
| | - Mutlu U Yazıcı
- Sami Ulus Children Hospital, Intensive Care Unit, Ankara, Turkey
| | - Fatih S Ezgu
- Department of Pediatrics, Metabolism Unit, Gazi University, Ankara, Turkey
| | - Turgay Coskun
- Department of Pediatrics, Metabolism Unit, Hacettepe University, Ankara, Turkey
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9
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Bagheri-Fam S, Chen H, Wilson S, Ayers K, Hughes J, Sloan-Bena F, Calvel P, Robevska G, Puisac B, Kusz-Zamelczyk K, Gimelli S, Spik A, Jaruzelska J, Warenik-Szymankiewicz A, Faradz S, Nef S, Pié J, Thomas P, Sinclair A, Wilhelm D. The gene encoding the ketogenic enzyme HMGCS2 displays a unique expression during gonad development in mice. PLoS One 2020; 15:e0227411. [PMID: 31910233 PMCID: PMC6946174 DOI: 10.1371/journal.pone.0227411] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Accepted: 12/18/2019] [Indexed: 11/26/2022] Open
Abstract
Disorders/differences of sex development (DSD) cause profound psychological and reproductive consequences for the affected individuals, however, most are still unexplained at the molecular level. Here, we present a novel gene, 3-hydroxy-3-methylglutaryl coenzyme A synthase 2 (HMGCS2), encoding a metabolic enzyme in the liver important for energy production from fatty acids, that shows an unusual expression pattern in developing fetal mouse gonads. Shortly after gonadal sex determination it is up-regulated in the developing testes following a very similar spatial and temporal pattern as the male-determining gene Sry in Sertoli cells before switching to ovarian enriched expression. To test if Hmgcs2 is important for gonad development in mammals, we pursued two lines of investigations. Firstly, we generated Hmgcs2-null mice using CRISPR/Cas9 and found that these mice had gonads that developed normally even on a sensitized background. Secondly, we screened 46,XY DSD patients with gonadal dysgenesis and identified two unrelated patients with a deletion and a deleterious missense variant in HMGCS2 respectively. However, both variants were heterozygous, suggesting that HMGCS2 might not be the causative gene. Analysis of a larger number of patients in the future might shed more light into the possible association of HMGCS2 with human gonadal development.
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Affiliation(s)
- Stefan Bagheri-Fam
- Department of Anatomy & Neuroscience, The University of Melbourne, Melbourne, Australia
| | - Huijun Chen
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, Australia
| | - Sean Wilson
- Murdoch Children’s Research Institute, Melbourne, Australia
| | - Katie Ayers
- Murdoch Children’s Research Institute, Melbourne, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - James Hughes
- School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | | | - Pierre Calvel
- Department of Genetics, Medicine & Development, University of Geneva, Geneva, Switzerland
| | - Gorjana Robevska
- Murdoch Children’s Research Institute, Melbourne, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - Beatriz Puisac
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, CIBERER-GCV02 and ISS-Aragon, Zaragoza, Spain
| | | | - Stefania Gimelli
- Service of Genetic Medicine, University Geneva Hospitals, Geneva, Switzerland
| | - Anna Spik
- Institute of Human Genetics, Polish Academy of Sciences, Poznań, Poland
| | | | | | - Sultana Faradz
- Center for Biomedical Research Faculty of Medicine Diponegoro University (FMDU), Semarang, Indonesia
| | - Serge Nef
- Service of Genetic Medicine, University Geneva Hospitals, Geneva, Switzerland
| | - Juan Pié
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, CIBERER-GCV02 and ISS-Aragon, Zaragoza, Spain
| | - Paul Thomas
- School of Biological Sciences, University of Adelaide, Adelaide, Australia
| | - Andrew Sinclair
- Murdoch Children’s Research Institute, Melbourne, Australia
- Department of Paediatrics, The University of Melbourne, Melbourne, Australia
| | - Dagmar Wilhelm
- Department of Anatomy & Neuroscience, The University of Melbourne, Melbourne, Australia
- * E-mail:
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10
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Severe clinical manifestation of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency associated with two novel mutations: a case report. BMC Pediatr 2019; 19:344. [PMID: 31597564 PMCID: PMC6784346 DOI: 10.1186/s12887-019-1747-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 09/24/2019] [Indexed: 11/29/2022] Open
Abstract
Background Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase (mHS) deficiency is an autosomal recessive inborn error of metabolism, which will give rise to failure of ketogenesis in liver during illness or fasting. It is a very rare disease with only a few patients reported worldwide, most of which had a good prognosis after proper therapies. Case presentation We report a 9-month-old boy with mHS deficiency presenting with unusually severe and persistent acidosis after diarrhea and reduced oral food intake. The metabolic acidosis persisted even after supplementation with sugar and alkaline solution. Blood purification and assisted respiration alleviated symptoms, but a second onset induced by respiratory infection several days later led to multiple organ failure and death. Urine organic acid analysis during the acute episode revealed a complex pattern of ketogenic dicarboxylic and 3-hydroxydicarboxylic aciduria with prominent elevation of glutaric acid and adipic acid, which seem to be specific to mHS deficiency. Plasma acylcarnitine analysis revealed elevated 3-hydroxybutyrylcarnitine and acetylcarnitine. This is the first report of elevated 3-hydroxybutyrylcarnitine in mHS deficiency. Whole exome sequencing revealed a novel compound heterozygous mutation in HMGCS2 (c.100C > T and c.1465delA). Conclusion This severe case suggests the need for patients with mHS deficiency to avoid recurrent illness because it can induce severe metabolic crisis, possibly leading to death. Such patients may also require special treatment, such as blood purification. Urine organic acid profile during the acute episode may give a hint to the disease.
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11
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Lee T, Takami Y, Yamada K, Kobayashi H, Hasegawa Y, Sasai H, Otsuka H, Takeshima Y, Fukao T. A Japanese case of mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency who presented with severe metabolic acidosis and fatty liver without hypoglycemia. JIMD Rep 2019; 48:19-25. [PMID: 31392109 PMCID: PMC6606983 DOI: 10.1002/jmd2.12051] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Revised: 05/15/2019] [Accepted: 05/15/2019] [Indexed: 11/17/2022] Open
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency (mHS deficiency) is a rare autosomal recessive inborn error of ketogenesis caused by a mutation in the HMGCS2 gene, which is characterized by non-(hypo)-ketotic hypoglycemia, lethargy, and hepatomegaly during acute infection and/or prolonged fasting. Clinical presentations are similar to fatty acid oxidation defects; however, diagnosis of mHS deficiency is difficult because of poor biochemical markers. We report the case of a 12-month-old Japanese boy with mHS deficiency who presented with a coma, and hepatomegaly, but no hypoglycemia after a febrile episode and poor oral intake. Metabolic acidosis and severe fatty liver were observed. Serum acylcarnitine analysis revealed a slightly decreased free carnitine (C0) level and an increased acetylcarnitine (C2) level. Urinary organic acid analysis revealed hypoketotic dicarboxylic aciduria, and increased excretions of glutarate, and, retrospectively, 4-hydroxy-6-methyl-2-pyrone. Although the patient did not present with hypoglycemia, the severe fatty liver and elevated free fatty acids to total ketone bodies ratio strongly suggested an inborn error of ketogenesis. In the analysis of the HMGCS2 gene, compound heterozygous mutations of c.130_131ins C (L44PfsX29) and c.1156_1157insC (L386PfsX73) were identified, which led to the diagnosis of mHS deficiency. He had recovered without any complication by the therapy, including intravenous glucose infusion. Unlike the previously reported cases of mHS deficiency, our case did not present with hypoglycemia and the fatty liver lasted over several months. mHS deficiency should be taken into consideration when a patient has severe metabolic acidosis and fatty liver with no or subtle ketosis, even without hypoglycemia.
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Affiliation(s)
- Tomoko Lee
- Department of PediatricsHyogo College of MedicineNishinomiyaJapan
| | - Yuichi Takami
- Department of PediatricsJapanese Red Cross Society Himeji HospitalHimejiJapan
| | - Kenji Yamada
- Department of PediatricsShimane University Faculty of MedicineIzumoJapan
| | - Hironori Kobayashi
- Department of PediatricsShimane University Faculty of MedicineIzumoJapan
| | - Yuki Hasegawa
- Department of PediatricsShimane University Faculty of MedicineIzumoJapan
| | - Hideo Sasai
- Department of PediatricsGraduate School of Medicine, Gifu UniversityGifuJapan
| | - Hiroki Otsuka
- Department of PediatricsGraduate School of Medicine, Gifu UniversityGifuJapan
| | | | - Toshiyuki Fukao
- Department of PediatricsGraduate School of Medicine, Gifu UniversityGifuJapan
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12
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Zhang P, Hu X, Guo R, Guo J, Li W, Qian S, Hao C, Liu J. Novel HMGCS2 pathogenic variants in a Chinese family with mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency. Pediatr Investig 2019; 3:86-90. [PMID: 32851297 PMCID: PMC7331301 DOI: 10.1002/ped4.12130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 04/22/2019] [Indexed: 11/10/2022] Open
Abstract
IMPORTANCE Mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase deficiency is a rare and underdiagnosed disorder with fewer than 30 patients reported worldwide. The application of whole-exome sequencing in patients could improve our understanding of this disorder. OBJECTIVE To identify the genetic causes and evaluate the phenotype of mitochondrial HMG-CoA synthase deficiency in a pediatric patient with uncommon features that included ketosis and elevated lactate and ammonia. METHODS The proband was referred to the pediatric intensive care unit of Beijing Children's Hospital and selected for molecular testing with whole-exome sequencing. Her parents and sibling also underwent sequencing for segregation information. RESULTS We identified two novel mutations (c.1347_1351delAGCCT/p.Ala450Profs*7 and c.1201G>T/ p.Glu401*) in the HMG-CoA synthase-2 gene (HMGCS2, NM_005518.3) in the proband and her brother. Both variants were classified as pathogenic variants according to the American College of Medical Genetics and Genomics/ Association for Molecular Pathology guidelines. Metabolic acidosis in the proband was corrected with continuous renal replacement therapy and she left hospital after 21 days of treatment. INTERPRETATION Our results extend the genotypic and phenotypic spectrum of HMGCS2 mutation in mitochondrial HMG-CoA synthase deficiency patients and serve as a reminder for physicians to consider mitochondrial HMG-CoA synthase deficiency in newborns and children with coma and hypoketotic hypoglycemia after fasting.
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Affiliation(s)
- Pengfei Zhang
- Department of Pediatric Intensive Care UnitBeijing Children's HospitalCapital Medical University; National Center for Children's HealthBeijing100045China
| | - Xuyun Hu
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Ruolan Guo
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Jun Guo
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Wei Li
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Suyun Qian
- Department of Pediatric Intensive Care UnitBeijing Children's HospitalCapital Medical University; National Center for Children's HealthBeijing100045China
| | - Chanjuan Hao
- Beijing Key Laboratory for Genetics of Birth DefectsBeijing Pediatric Research Institute; MOE Key Laboratory of Major Diseases in Children; Genetics and Birth Defects Control CenterBeijing Children's HospitalCapital Medical UniversityNational Center for Children's HealthBeijingChina
- Henan Key Laboratory of Pediatric Inherited & Metabolic DiseasesHenan Children's HospitalZhengzhou Hospital of Beijing Children's HospitalZhengzhouChina
| | - Jun Liu
- Department of Pediatric Intensive Care UnitBeijing Children's HospitalCapital Medical University; National Center for Children's HealthBeijing100045China
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13
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Puisac B, Marcos-Alcalde I, Hernández-Marcos M, Tobajas Morlana P, Levtova A, Schwahn BC, DeLaet C, Lace B, Gómez-Puertas P, Pié J. Human Mitochondrial HMG-CoA Synthase Deficiency: Role of Enzyme Dimerization Surface and Characterization of Three New Patients. Int J Mol Sci 2018; 19:ijms19041010. [PMID: 29597274 PMCID: PMC5979369 DOI: 10.3390/ijms19041010] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 03/23/2018] [Accepted: 03/26/2018] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency (mitochondrial HMG-CoA synthase deficiency or mHS deficiency, OMIM #605911) is an inborn error of metabolism that affects ketone body synthesis. Acute episodes include vomiting, lethargy, hepatomegaly, hypoglycemia and dicarboxylic aciduria. The diagnosis is difficult due to the relatively unspecific clinical and biochemical presentation, and fewer than 30 patients have been described. This work describes three new patients with mHS deficiency and two missense mutations c.334C>T (p.R112W) and c.430G>T (p.V144L) previously not reported. We developed a new method to express and measure the activity of the enzyme and in this work the study is extended to ten new missense variants including those of our patients. Enzymatic assays showed that three of the mutant proteins retained some but seven completely lacked activity. The identification of a patient homozygous for a mutation that retains 70% of enzyme activity opens the door to a new interpretation of the disease by demonstrating that a modest impairment of enzyme function can actually produce symptoms. This is also the first study employing molecular dynamics modelling of the enzyme mutations. We show that the correct maintenance of the dimerization surface is crucial for retaining the structure of the active center and therefore the activity of the enzyme.
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Affiliation(s)
- Beatriz Puisac
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, CIBERER-GCV02 and ISS-Aragon, E-50009 Zaragoza, Spain.
| | - Iñigo Marcos-Alcalde
- Molecular Modelling Group, Center of Molecular Biology "Severo Ochoa" (CSIC-UAM), Cantoblanco, E-28049 Madrid, Spain.
- Faculty of Experimental Sciences, Francisco de Vitoria University, Pozuelo de Alarcón, 28223 Madrid, Spain.
| | - María Hernández-Marcos
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, CIBERER-GCV02 and ISS-Aragon, E-50009 Zaragoza, Spain.
| | - Pilar Tobajas Morlana
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, CIBERER-GCV02 and ISS-Aragon, E-50009 Zaragoza, Spain.
| | - Alina Levtova
- Division of Medical Genetics, Department of Medicine, CHUM (Centre Hospitalier Universitaire de l'Université de Montréal) and Université de Montréal, Montreal, QC H2X 0A9, Canada.
| | - Bernd C Schwahn
- Willink Metabolic Unit, Manchester Centre for Genomic Medicine, Saint Mary's Hospital, Manchester University Hospitals NHS Foundation Trust, Manchester M13 9WL, UK.
| | - Corinne DeLaet
- Hôpital Universitaire des Enfants Reine Fabiola, Avenue Crocq 15, B-1020 Brussels, Belgium.
| | - Baiba Lace
- Centre Hospitalier Universitaire de Québec, Québec City, QC G1V 4G2, Canada.
| | - Paulino Gómez-Puertas
- Molecular Modelling Group, Center of Molecular Biology "Severo Ochoa" (CSIC-UAM), Cantoblanco, E-28049 Madrid, Spain.
| | - Juan Pié
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology-Physiology, School of Medicine, University of Zaragoza, CIBERER-GCV02 and ISS-Aragon, E-50009 Zaragoza, Spain.
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14
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Mitochondrial 3-Hydroxy-3-Methylglutaryl-CoA Synthase Deficiency: Unique Presenting Laboratory Values and a Review of Biochemical and Clinical Features. JIMD Rep 2017; 40:63-69. [PMID: 29030856 PMCID: PMC6122033 DOI: 10.1007/8904_2017_59] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Revised: 08/28/2017] [Accepted: 08/29/2017] [Indexed: 01/27/2023] Open
Abstract
We report an 8-month-old infant with decreased consciousness after a febrile episode and reduced oral intake. He was profoundly acidotic but his lactate was normal. Serum triglycerides were markedly elevated and HDL cholesterol was very low. The urine organic acid analysis during the acute episode revealed a complex pattern of relative hypoketotic dicarboxylic aciduria, suggestive of a potential fatty acid oxidation disorder. MRI showed extensive brain abnormalities concerning for a primary energy deficiency. Whole exome sequencing revealed heterozygotic HMGCS2 variants. HMGCS2 encodes mitochondrial 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) synthase-2 (HMGCS2), which catalyzes the irreversible and rate-limiting reaction of ketogenesis in the mitochondrial matrix. Autosomal recessive HMG-CoA synthase deficiency (HMGCS2D) is characterized by hypoketotic hypoglycemia, vomiting, lethargy, and hepatomegaly after periods of prolonged fasting or illness. A retrospective analysis of the urine organic acid analysis identified 4-hydrox-6-methyl-2-pyrone, a recently reported putative biomarker of HMGCS2D. There was also a relative elevation of plasma acetylcarnitine as previously reported in one case. Our patient highlights a unique presentation of HMGCS2D caused by novel variants in HMGCS2. This is the first report of HMGCS2D with a significantly elevated triglyceride level and decreased HDL cholesterol level at presentation. Given this, we suggest that HMGCS2D should be considered in the differential diagnosis when hypertriglyceridemia, or low HDL cholesterol levels are seen in a child who presents with acidosis, mild ketosis, and mental status changes after illness or prolonged fasting. Although HMGCS2D is a rare disorder with nonspecific symptoms, with the advent of next-generation sequencing, and the recognition of novel biochemical biomarkers, the incidence of this condition may become better understood.
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15
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Pitt JJ, Peters H, Boneh A, Yaplito-Lee J, Wieser S, Hinderhofer K, Johnson D, Zschocke J. Mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase deficiency: urinary organic acid profiles and expanded spectrum of mutations. J Inherit Metab Dis 2015; 38:459-66. [PMID: 25511235 DOI: 10.1007/s10545-014-9801-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 11/08/2014] [Accepted: 11/25/2014] [Indexed: 10/24/2022]
Abstract
Mitochondrial 3-hydroxy-3-methylglutaryl CoA synthase (HMCS2) deficiency results in episodes of hypoglycemia and increases in fatty acid metabolites. Metabolite abnormalities described to date in HMCS2 deficiency are nonspecific and overlap with other inborn errors of metabolism, making the biochemical diagnosis of HMCS2 deficiency difficult. Urinary organic acid profiles from periods of metabolic decompensation were studied in detail in HMCS2-deficient patients from four families. An additional six unrelated patients were identified from clinical presentation and/or qualitative identification of abnormal organic acids. The diagnosis was confirmed by sequencing and deletion/duplication analysis of the HMGCS2 gene. Seven related novel organic acids were identified in urine profiles. Five of them (3,5-dihydroxyhexanoic 1,5 lactone; trans-5-hydroxyhex-2-enoate; 4-hydroxy-6-methyl-2-pyrone; 5-hydroxy-3-ketohexanoate; 3,5-dihydroxyhexanoate) were identified by comparison with synthesized or commercial authentic compounds. We provisionally identified trans-3-hydroxyhex-4-enoate and 3-hydroxy-5-ketohexanoate by their mass spectral characteristics. These metabolites were found in samples taken during periods of decompensation and normalized when patients recovered. When cutoffs of adipic >200 and 4-hydroxy-6-methyl-2-pyrone >20 μmol/mmol creatinine were applied, all eight samples taken from five HMCS2-deficient patients during episodes of decompensation were flagged with a positive predictive value of 80% (95% confidence interval 35-100%). Some ketotic patients had increased 4-hydroxy-6-methyl-2-pyrone. Molecular studies identified a total of 12 novel mutations, including a large deletion of HMGCS2 exon 1 in two families, highlighting the need to perform quantitative gene analyses. There are now 26 known HMGCS2 mutations, which are reviewed in the text. 4-Hydroxy-6-methyl-2-pyrone and related metabolites are markers for HMCS2 deficiency. Detection of these metabolites will streamline the biochemical diagnosis of this disorder.
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Affiliation(s)
- James J Pitt
- Victorian Clinical Genetics Services, Murdoch Childrens Research Institute, Royal Children's Hospital, Parkville, VIC, 3052, Australia,
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16
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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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17
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Ramos M, Menao S, Arnedo M, Puisac B, Gil-Rodríguez MC, Teresa-Rodrigo ME, Hernández-Marcos M, Pierre G, Ramaswami U, Baquero-Montoya C, Bueno G, Casale C, Hegardt FG, Gómez-Puertas P, Pié J. New case of mitochondrial HMG-CoA synthase deficiency. Functional analysis of eight mutations. Eur J Med Genet 2013; 56:411-5. [PMID: 23751782 DOI: 10.1016/j.ejmg.2013.05.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 05/27/2013] [Indexed: 11/29/2022]
Abstract
Mitochondrial HMG-CoA synthase deficiency is a rare inherited metabolic disorder that affects ketone-body synthesis. Acute episodes include vomiting, lethargy, hepatomegaly, hypoglycaemia, dicarboxylic aciduria, and in severe cases, coma. This deficiency may have been under-diagnosed owing to the absence of specific clinical and biochemical markers, limitations in liver biopsy and the lack of an effective method of expression and enzyme assay for verifying the mutations found. To date, eight patients have been reported with nine allelic variants of the HMGCS2 gene. We present a new method of enzyme expression and a modification of the activity assay that allows, for first time, the functional study of missense mutations found in patients with this deficiency. Four of the missense mutations (p.V54M, p.R188H, p.G212R and p.G388R) did not produce proteins that could have been detected in soluble form by western blot; three produced a total loss of activity (p.Y167C, p.M307T and p.R500H) and one, variant p.F174L, gave an enzyme with a catalytic efficiency of 11.5%. This indicates that the deficiency may occur with partial loss of activity of enzyme. In addition, we describe a new patient with this deficiency, in which we detected the missense allelic variant, c.1162G>A (p.G388R) and the nonsense variant c.1270C>T (p.R424X).
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Affiliation(s)
- Mónica Ramos
- Unit of Clinical Genetics and Functional Genomics, Department of Pharmacology Physiology, Medical School, University of Zaragoza, Spain
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18
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Daniels TF, Killinger KM, Michal JJ, Wright RW, Jiang Z. Lipoproteins, cholesterol homeostasis and cardiac health. Int J Biol Sci 2009; 5:474-88. [PMID: 19584955 PMCID: PMC2706428 DOI: 10.7150/ijbs.5.474] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2009] [Accepted: 06/19/2009] [Indexed: 12/22/2022] Open
Abstract
Cholesterol is an essential substance involved in many functions, such as maintaining cell membranes, manufacturing vitamin D on surface of the skin, producing hormones, and possibly helping cell connections in the brain. When cholesterol levels rise in the blood, they can, however, have dangerous consequences. In particular, cholesterol has generated considerable notoriety for its causative role in atherosclerosis, the leading cause of death in developed countries around the world. Homeostasis of cholesterol is centered on the metabolism of lipoproteins, which mediate transport of the lipid to and from tissues. As a synopsis of the major events and proteins that manage lipoprotein homeostasis, this review contributes to the substantial attention that has recently been directed to this area. Despite intense scrutiny, the majority of phenotypic variation in total cholesterol and related traits eludes explanation by current genetic knowledge. This is somewhat disappointing considering heritability estimates have established these traits as highly genetic. Thus, the continued search for candidate genes, mutations, and mechanisms is vital to our understanding of heart disease at the molecular level. Furthermore, as marker development continues to predict risk of vascular illness, this knowledge has the potential to revolutionize treatment of this leading human disease.
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Affiliation(s)
- Tyler F Daniels
- Department of Animal Sciences, Washington State University, Pullman, WA 99164-6351, USA
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19
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Andringa KK, Bajt ML, Jaeschke H, Bailey SM. Mitochondrial protein thiol modifications in acetaminophen hepatotoxicity: effect on HMG-CoA synthase. Toxicol Lett 2008; 177:188-97. [PMID: 18313239 DOI: 10.1016/j.toxlet.2008.01.010] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 01/17/2008] [Accepted: 01/17/2008] [Indexed: 01/15/2023]
Abstract
Acetaminophen (APAP) overdose is the leading cause of drug related liver failure in many countries. N-acetyl-p-benzoquinone imine (NAPQI) is a reactive metabolite that is formed by the metabolism of APAP. NAPQI preferentially binds to glutathione and then cellular proteins. NAPQI binding is considered an upstream event in the pathophysiology, especially when binding to mitochondrial proteins and therefore leads to mitochondrial toxicity. APAP caused a significant increase in liver toxicity 3h post-APAP administration as measured by increased serum alanine aminotransferase (ALT) levels. Using high-resolution mitochondrial proteomics techniques to measure thiol and protein changes, no significant change in global thiol levels was observed. However, 3-hydroxy-3-methylglutaryl coenzyme A synthase 2 (HMG-CoA synthase) had significantly decreased levels of reduced thiols and activity after APAP treatment. HMG-CoA synthase is a key regulatory enzyme in ketogenesis and possesses a number of critical cysteines in the active site. Similarly, catalase, a key enzyme in hydrogen peroxide metabolism, also showed modification in protein thiol content. These data indicate post-translational modifications of a few selected proteins involved in mitochondrial and cellular regulation of metabolism during liver toxicity after APAP overdose. The pathophysiological relevance of these limited changes in protein thiols remains to be investigated.
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Affiliation(s)
- Kelly K Andringa
- Department of Environmental Health Sciences and The Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL 35294, United States
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20
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Aledo R, Mir C, Dalton RN, Turner C, Pié J, Hegardt FG, Casals N, Champion MP. Refining the diagnosis of mitochondrial HMG-CoA synthase deficiency. J Inherit Metab Dis 2006; 29:207-11. [PMID: 16601895 DOI: 10.1007/s10545-006-0214-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Mitochondrial HMG-CoA synthase deficiency is an inherited metabolic disorder caused by a defect in the enzyme that regulates the formation of ketone bodies. Patients present with hypoketotic hypoglycaemia, encephalopathy and hepatomegaly, usually precipitated by an intercurrent infection or prolonged fasting. The diagnosis may easily be missed as previously reported results of routine metabolic investigations, urinary organic acids and plasma acylcarnitines may be nonspecific or normal, and a high index of suspicion is required to proceed to further confirmatory tests. We describe a further acute case in which the combination of urinary organic acids, low free carnitine and changes in the plasma acylcarnitine profile on carnitine supplementation were very suggestive of a defect in ketone synthesis. The diagnosis of mitochondrial HMG-CoA synthase deficiency was confirmed on genotyping, revealing two novel mutations: c.614G > A (R188H) and c.971T > C (M307T). A further sibling, in whom the diagnosis had not been made acutely, was also found to be affected. The possible effects of these mutations on enzyme activity are discussed.
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Affiliation(s)
- R Aledo
- Unit of Biochemistry and Molecular Biology, School of Health Sciences, International University of Catalonia, Spain
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