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Yao D, Yao M, Yamaguchi M, Chida J, Kido H. Characterization of compound missense mutation and deletion of carnitine palmitoyltransferase II in a patient with adenovirus-associated encephalopathy. THE JOURNAL OF MEDICAL INVESTIGATION 2012; 58:210-8. [PMID: 21921422 DOI: 10.2152/jmi.58.210] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND In mammals, carnitine palmitoyltransferase (CPT) system is a pivotal component of energy metabolism through mitochondrial fatty acid oxidation. The majority of patients with fatal or handicapped influenza-associated encephalopathy exhibit thermolabile compound homo/heterozygous mutations of CPT II. OBJECTIVE Compound CPT II mutations, [c.647A>G (p.Q216R)], [c.1102G>A (p.V368I)], [c.1939A>G (p.M647V)] and [c.745delG (p.G249EfsX16)], were found in a patient with adenovirus-associated encephalopathy and his family. The properties of these CPT II mutations were analyzed in COS-7 cells. METHODS CPT II mutations in the patient and his family were expressed in COS-7 cells and their molecular masses, enzyme activities, thermal instabilities and half-lives were analyzed. RESULTS We identified two novel CPT II mutations in the patient, [c.647A>G (p.Q216R)] and [c.745delG (p.G249EfsX16)]. The CPT II Q216R mutation showed mild reduction of activity, thermal instability and short half-life but compound mutations with Q216R+V368I+M647V showed further enhancement of these disabilities, although mutations V368I and M647V had no such effects. CPT II mutation [c.745delG (p.G249EfsX16)] abolished enzyme activity and showed short half-life. CONCLUSION The thermal instability and short half-life of the novel CPT II mutations, [c.647A>G (p.Q216R)] and [c.745delG (p.G249EfsX16)], could play important roles in energy crisis in the pathogenesis of virus-associated encephalopathy.
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Affiliation(s)
- Dengbing Yao
- Division of Enzyme Chemistry, Institute for Enzyme Research, University of Tokushima, Tokushima, Japan
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2
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Fanin M, Anichini A, Cassandrini D, Fiorillo C, Scapolan S, Minetti C, Cassanello M, Donati MA, Siciliano G, D'Amico A, Lilliu F, Bruno C, Angelini C. Allelic and phenotypic heterogeneity in 49 Italian patients with the muscle form of CPT-II deficiency. Clin Genet 2011; 82:232-9. [PMID: 21913903 DOI: 10.1111/j.1399-0004.2011.01786.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
As genotype-phenotype correlations require the study of large patient populations, we investigated 49 Italian patients (33 unreported) with the muscle form of carnitine-palmitoyl-transferase-II (CPT-II) deficiency and CPT2 gene mutations. CPT enzyme activity below 25% of controls would lead to the development of muscle symptoms, and CPT activity below 15% would cause a relatively severe phenotype of the muscle form. Of the 15 different mutations found, 6 are novel (40%). A functional significance of mutations could be derived only for the two homozygous missense mutations found: both the p.S113L and the p.R631C (recurring in four unrelated patients from a genetic isolate) alleles caused a severe CPT enzyme defect (15% and 7%, respectively) and a relatively severe clinical phenotype of the muscle form. We identified three genotypes (homozygous p.R631C, homozygous p.S113L, and heterozygous null mutations) usually associated with a relatively severe and often life-threatening condition, which should be considered both in the clinical management of newly diagnosed patients (to prevent symptoms) and in their possible inclusion in therapeutic trials. We confirmed the existence of symptomatic heterozygous patient(s), through a family study, providing an important issue when offering genetic counseling and suggesting the crucial role of polymorphisms or environmental factors in determining the phenotype.
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Affiliation(s)
- M Fanin
- Neuromuscular Center, Department of Neurosciences, University of Padova, Padova, Italy.
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3
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Yamamoto T, Tanaka H, Kobayashi H, Okamura K, Tanaka T, Emoto Y, Sugimoto K, Nakatome M, Sakai N, Kuroki H, Yamaguchi S, Matoba R. Retrospective review of Japanese sudden unexpected death in infancy: the importance of metabolic autopsy and expanded newborn screening. Mol Genet Metab 2011; 102:399-406. [PMID: 21227726 DOI: 10.1016/j.ymgme.2010.12.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 12/07/2010] [Indexed: 11/29/2022]
Abstract
Sudden unexpected death in infancy is defined as sudden unexpected death occurring before 12 months of age. The common causes of sudden unexpected death in infancy are infection, cardiovascular anomaly, child abuse, and metabolic disorders. However, the many potential inherited metabolic disorders are difficult to diagnose at autopsy and may therefore be underdiagnosed as a cause of sudden unexpected death in infancy. In the present study we retrospectively reviewed 30 Japanese sudden unexpected death in infancy cases encountered between 2006 and 2009 at our institute. With postmortem blood acylcarnitine analysis and histological examination of the liver, we found two cases of long-chain fatty acid oxidation defects. Molecular analysis revealed that the one patient had a compound heterozygote for a novel mutation (p.L644S) and a disease-causing mutation (p.F383Y) in the carnitine palmitoyltransferase 2 gene. Furthermore, retrospective acylcarnitine analysis of the newborn screening card of this patient was consistent with carnitine palmitoyltransferase II deficiency. Metabolic autopsy and expanded newborn screening would be helpful for forensic scientists and pediatricians to diagnose fatty acid oxidation disorders and prevent sudden unexpected death in infancy.
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Affiliation(s)
- Takuma Yamamoto
- Department of Legal Medicine, Osaka University Graduate School of Medicine, 2-2 Yamada-Oka, Suita, Osaka 565-0871, Japan
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4
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Roe CR, Yang BZ, Brunengraber H, Roe DS, Wallace M, Garritson BK. Carnitine palmitoyltransferase II deficiency: successful anaplerotic diet therapy. Neurology 2008; 71:260-4. [PMID: 18645163 DOI: 10.1212/01.wnl.0000318283.42961.e9] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Carnitine palmitoyltransferase II (CPT II) deficiency is an important cause of recurrent rhabdomyolysis in children and adults. Current treatment includes dietary fat restriction, with increased carbohydrate intake and exercise restriction to avoid muscle pain and rhabdomyolysis. METHODS CPT II enzyme assay, DNA mutation analysis, quantitative analysis of acylcarnitines in blood and cultured fibroblasts, urinary organic acids, the standardized 36-item Short-Form Health Status survey (SF-36) version 2, and bioelectric impedance for body fat composition. Diet treatment with triheptanoin at 30% to 35% of total daily caloric intake was used for all patients. RESULTS Seven patients with CPT II deficiency were studied from 7 to 61 months on the triheptanoin (anaplerotic) diet. Five had previous episodes of rhabdomyolysis requiring hospitalizations and muscle pain on exertion prior to the diet (two younger patients had not had rhabdomyolysis). While on the diet, only two patients experienced mild muscle pain with exercise. During short periods of noncompliance, two patients experienced rhabdomyolysis with exercise. None experienced rhabdomyolysis or hospitalizations while on the diet. All patients returned to normal physical activities including strenuous sports. Exercise restriction was eliminated. Previously abnormal SF-36 physical composite scores returned to normal levels that persisted for the duration of the therapy in all five symptomatic patients. CONCLUSIONS The triheptanoin diet seems to be an effective therapy for adult-onset carnitine palmitoyltransferase II deficiency.
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Affiliation(s)
- C R Roe
- Institute of Metabolic Disease, Baylor University Medical Center, 3812 Elm St., Dallas, TX 75226, USA.
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5
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Yao D, Mizuguchi H, Yamaguchi M, Yamada H, Chida J, Shikata K, Kido H. Thermal instability of compound variants of carnitine palmitoyltransferase II and impaired mitochondrial fuel utilization in influenza-associated encephalopathy. Hum Mutat 2008; 29:718-27. [PMID: 18306170 DOI: 10.1002/humu.20717] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Influenza-associated encephalopathy (IAE) is characterized by persistent high fever, febrile convulsions, severe brain edema, and high mortality in otherwise apparently healthy individuals. We have reported that a large proportion of patients suffering from disabling or fatal IAE, with transiently elevated serum acylcarnitine during high fever, exhibit a thermolabile phenotype of compound homo-/heterozygous variants of carnitine palmitoyltransferase II (CPT II, gene symbol CPT2). We characterized the enzymatic properties of five single and three compound CPT II variants in patients with IAE. The kinetic characteristics of WT and variant CPT IIs, expressed in COS-7 cells, indicated that the variants exert a dominant-negative effect on the homotetrameric protein of the enzyme. Among the variants, three compound variations found in patients with severe encephalopathy; [c.1055T>G (p.Phe352Cys); c.1102G>A (p.Val368Ile)], [c.1511C>T (p.Pro504Leu); c.1813G>C (p.Val605Leu)], and [c.1055T>G (p.Phe352Cys); c.1102G>A (p.Val368Ile); c.1813G>C (p.Val605Leu)], showed reduced activities, thermal instability, and short half-lives compared with the WT. Like other disease-causing mutant proteins, these variant proteins were poly-ubiquitinated and rapidly degraded by a lactacystin-sensitive proteasome pathway. COS-7 cells transfected with the compound variants had their fatty acid beta-oxidation decreased to 30-59% and intracellular ATP levels to 48-79%, and a marked reduction of mitochondrial membrane potential at 41 degrees C, compared with control cells transfected with WT at 37 degrees C. The unstable CPT II variants with decreased enzymatic activities may bring mitochondrial fuel utilization below the phenotypic threshold during high fever, and thus may play an important etiopathological role in the development of brain edema of IAE.
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Affiliation(s)
- Dengbing Yao
- Division of Enzyme Chemistry, Institute for Enzyme Research, The University of Tokushima, Tokushima, Japan
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6
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Isackson PJ, Bennett MJ, Lichter-Konecki U, Willis M, Nyhan WL, Sutton VR, Tein I, Vladutiu GD. CPT2 gene mutations resulting in lethal neonatal or severe infantile carnitine palmitoyltransferase II deficiency. Mol Genet Metab 2008; 94:422-427. [PMID: 18550408 DOI: 10.1016/j.ymgme.2008.05.002] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 05/05/2008] [Accepted: 05/05/2008] [Indexed: 10/22/2022]
Abstract
Three distinct clinical manifestations of carnitine palmitoyltransferase II (CPT II) deficiency have been defined including a mild adult onset myopathy, a severe infantile disorder and a lethal neonatal form. In this study we have examined the genomic DNA of five patients, 3 with the lethal neonatal form and 2 with the severe infantile form of the disease and identified two disease-causing mutations in the CPT2 gene for each patient, three of which are novel. In addition, based on currently available structural, biochemical and clinical data, we have classified all 64 known disease-causing mutations into groups with different predicted phenotypes depending on their CPT2 allelic counterparts.
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Affiliation(s)
- Paul J Isackson
- Department of Pediatrics, School of Medicine & Biomedical Sciences, State University of New York at Buffalo, SUNY at Buffalo, 100 High Street, Buffalo, NY 14203, USA
| | - Michael J Bennett
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine and Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Uta Lichter-Konecki
- Department of Pediatrics, The George Washington University Medical Center & Children's National Medical Center, Washington, DC, USA
| | - Mary Willis
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - William L Nyhan
- Department of Pediatrics, University of California San Diego, La Jolla, CA, USA
| | - V Reid Sutton
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Ingrid Tein
- Division of Neurology, The Research Institute, The Hospital for Sick Children & The University of Toronto, Toronto, Ont., Canada
| | - Georgirene D Vladutiu
- Department of Pediatrics, School of Medicine & Biomedical Sciences, State University of New York at Buffalo, SUNY at Buffalo, 100 High Street, Buffalo, NY 14203, USA
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7
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Isackson PJ, Bennett MJ, Vladutiu GD. Identification of 16 new disease-causing mutations in the CPT2 gene resulting in carnitine palmitoyltransferase II deficiency. Mol Genet Metab 2006; 89:323-31. [PMID: 16996287 DOI: 10.1016/j.ymgme.2006.08.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/03/2006] [Revised: 08/09/2006] [Accepted: 08/09/2006] [Indexed: 11/24/2022]
Abstract
The exonic regions of the carnitine palmitoyltransferase 2 (CPT2) gene were characterized from 101 patients with defined clinical and biochemical evidence for the adult onset form of CPT II deficiency and in 2 patients detected as newborns with abnormal acylcarnitine profiles. Twenty-seven disease-causing mutations within the CPT2 gene were identified in this cohort, 16 of which were novel. A total of 60 disease-causing mutations have been identified to date in CPT2 and 41 of these are predicted to produce amino acid substitution/deletions. The implications of these mutations are described in light of recent advances in our understanding of the molecular structure of members of the carnitine acyltransferase family.
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Affiliation(s)
- Paul J Isackson
- Department of Pediatrics, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, Buffalo, NY 14209, USA
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8
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Pedersen CB, Bischoff C, Christensen E, Simonsen H, Lund AM, Young SP, Koeberl DD, Millington DS, Roe CR, Roe DS, Wanders RJA, Ruiter JPN, Keppen LD, Stein Q, Knudsen I, Gregersen N, Andresen BS. Variations in IBD (ACAD8) in children with elevated C4-carnitine detected by tandem mass spectrometry newborn screening. Pediatr Res 2006; 60:315-20. [PMID: 16857760 DOI: 10.1203/01.pdr.0000233085.72522.04] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The isobutyryl-CoA dehydrogenase (IBD) enzyme is involved in the degradation of valine. IBD deficiency was first reported in 1998 and subsequent genetic investigations identified acyl-CoA dehydrogenase (ACAD) 8, now IBD, as the gene responsible for IBD deficiency. Only three individuals homozygous or compound heterozygous for variations in the IBD gene have been reported. We present IBD deficiency in an additional four newborns with elevated C(4)-carnitine identified by tandem mass spectrometry (MS/MS) screening in Denmark and the United States. Three showed urinary excretions of isobutyryl-glycine, and in vitro probe analysis of fibroblasts from two newborns indicated enzymatic IBD defect. Molecular genetic analysis revealed seven new rare variations in the IBD gene (c.348C>A, c.400G>T, c.409G>A, c.455T>C, c.958G>A, c.1000C>T and c.1154G>A). Furthermore, sequence analysis of the short-chain acyl-CoA dehydrogenase (SCAD) gene revealed heterozygosity for the prevalent c.625G>A susceptibility variation in all newborns and in the first reported IBD patient. Functional studies in isolated mitochondria demonstrated that the IBD variations present in the Danish newborn (c.409G>A and c.958G>A) together with a previously published IBD variation (c.905G>A) disturbed protein folding and reduced the levels of correctly folded IBD tetramers. Accordingly, low/no IBD residual enzyme activity was detectable when the variant IBD proteins were overexpressed in Chang cells.
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Affiliation(s)
- Christina B Pedersen
- Research Unit for Molecular Medicine, Aarhus University Hospital, Skejby Sygehus, 8200 Aarhus N, Denmark
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9
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Kaneoka H, Uesugi N, Moriguchi A, Hirose S, Takayanagi M, Yamaguchi S, Shigematsu Y, Yasuno T, Sasatomi Y, Saito T. Carnitine palmitoyltransferase II deficiency due to a novel gene variant in a patient with rhabdomyolysis and ARF. Am J Kidney Dis 2005; 45:596-602. [PMID: 15754283 DOI: 10.1053/j.ajkd.2004.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Adult patients deficient in carnitine palmitoyltransferase II (CPT II) cannot generate sufficient amounts of energy, which results in rhabdomyolysis and acute renal failure (ARF). Its genetic basis has been recognized; but histopathologic changes, especially electron microscopic changes, have scarcely been described. The study subject is a patient with ARF caused by repetitive nontraumatic rhabdomyolysis. The acylcarnitine profile of serum and enzyme assay on skin fibroblasts confirmed the diagnosis of CPT II deficiency. Renal biopsy specimens were examined microscopically and immunohistochemically. The histological diagnosis was interstitial nephritis with acute tubular necrosis caused by rhabdomyolysis. Myoglobin in tubules was detected by means of immunohistochemistry and electron microscopy. The genetic structure of CPT II was analyzed in the patient and his family. Eight pairs of polymerase chain reaction (PCR) primers were designed to cover the coding region. Each PCR-amplified gene product was subjected to DNA sequencing, which unveiled heterozygosity at the CPT II locus consisting of a deletion of cytosine and thymine at codon 408, resulting in a stop signal at 420, as well as a mutation of arginine to cysteine at codon 631. The frame shift at 408 has never been described before. DNA sequencing of the family showed the deletion mutation from the mother and the point mutation from the father. We describe renopathological findings in a patient with CPT II deficiency associated with rhabdomyolysis, which suggested the pathological role of myoglobin casts in the development of tubular necrosis. Genetic analysis of the patient identified a novel variant of the CPT II gene.
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Affiliation(s)
- Hidetoshi Kaneoka
- Department of Internal Medicine, Division of Nephrology and Rheumatology, Fukuoka University School of Medicine, Fukuoka, Japan.
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Sigauke E, Rakheja D, Kitson K, Bennett MJ. Carnitine palmitoyltransferase II deficiency: a clinical, biochemical, and molecular review. J Transl Med 2003; 83:1543-54. [PMID: 14615409 DOI: 10.1097/01.lab.0000098428.51765.83] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Congenital deficiency of carnitine palmitoyltransferase (CPT) II has been known for at least 30 years now, and its phenotypic variability remains fascinating. Three distinct clinical entities have been described, the adult, the infantile, and the perinatal, all with an autosomal recessive inheritance pattern. The adult CPT II clinical phenotype is somewhat benign and requires additional external triggers such as high-intensity exercise before the predominantly myopathic symptoms are elicited. The perinatal and infantile forms involve multiple organ systems. The perinatal disease is the most severe form and is invariably fatal. The introduction of mass spectrometry to analyze blood acylcarnitine profiles has revolutionized the diagnosis of fatty acid oxidation disorders including CPT II deficiency. Its use in expanded neonatal screening programs has made presymptomatic diagnosis a reality. An increasing number of mutations are being identified in the CPT II gene with a distinct genotype-phenotype correlation in most cases. However, clinical variability in some patients suggests additional genetic or environmental modifiers. Herein, we present a new case of lethal perinatal CPT II deficiency with a rare missense mutation, R296Q (907G>A) associated with a previously described 25-bp deletion on the second allele. We review the clinical features, the diagnostic protocol including expanded neonatal screening, the treatment, and the biochemical and molecular basis of CPT II deficiency.
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Affiliation(s)
- Ellen Sigauke
- Department of Pathology, The University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
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Olpin SE, Afifi A, Clark S, Manning NJ, Bonham JR, Dalton A, Leonard JV, Land JM, Andresen BS, Morris AA, Muntoni F, Turnbull D, Pourfarzam M, Rahman S, Pollitt RJ. Mutation and biochemical analysis in carnitine palmitoyltransferase type II (CPT II) deficiency. J Inherit Metab Dis 2003; 26:543-57. [PMID: 14605500 DOI: 10.1023/a:1025947930752] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Carnitine palmitoyltransferase type II (CPT II) deficiency has three basic phenotypes, late-onset muscular (mild), infantile/juvenile hepatic (intermediate) and severe neonatal. We have measured fatty acid oxidation and CPT II activity and performed mutation studies in 24 symptomatic patients representing the full clinical spectrum of disease. Severe and intermediate phenotypes show a clear correlation with biochemical indices and genetic analysis revealed causative mutations in most patients. Studies of mild phenotypes suggest a more complex interaction, with higher residual fatty acid oxidation, a wider range of CPT II activity (10-60%) but little evidence of genotype-phenotype correlation. Residual CPT II mutant protein from myopathic patients shows thermal instability at 41 degrees C. The common 'polymorphisms' V3681 and M647V are strikingly overrepresented in the myopathic patients, the implication being that they may significantly influence the manifestation of clinical disease and could therefore potentially be considered as a susceptibility variants. Among myopathic individuals, males comprised 88% of patients, suggesting increased susceptibility to clinical disease. A small number of symptomatic patients appear to have significant residual CPT II activity (42-60%) The synergistic interaction of partial deficiencies of CPT II, muscle adenosine monophosphate deaminase and possibly other enzymes of muscle energy metabolism in the aetiology of episodic myopathy deserves wider consideration.
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Affiliation(s)
- S E Olpin
- Department of Clinical Chemistry, Sheffield Children's Hospital, UK
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12
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Deschauer M, Wieser T, Schröder R, Zierz S. A novel nonsense mutation (515del4) in muscle carnitine palmitoyltransferase II deficiency. Mol Genet Metab 2002; 75:181-5. [PMID: 11855939 DOI: 10.1006/mgme.2001.3281] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We identified a novel nonsense mutation in the carnitine palmitoyltransferase (CPT; EC 2.3.1.21) II gene in a patient with biochemical evidence of CPT II deficiency. The 39-year-old man suffered from the muscle form of CPT II deficiency. Attacks of myalgia and muscle weakness started in childhood and led to renal failure five times. A mild proximal weakness of the lower limbs was left as a residue. Molecular genetic analysis revealed the common S113L mutation on one allele. On the other allele a novel 4-bp deletion starting at codon 515 (515del4) was found leading to frameshift that results in a stop codon 15 codons upstream. Our data further expand the genetic heterogeneity in patients with CPT II deficiency.
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Affiliation(s)
- Marcus Deschauer
- Department of Neurology, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Strasse 40, 06097 Halle/Saale, Germany.
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13
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Abstract
The most common form of carnitine palmitoyltransferase II (CPT II) deficiency occurs in adults and is characterized by muscle pain, stiffness, and myoglobinuria, triggered by exercise, fasting, or other metabolic stress. This study reports the molecular heterogeneity of CPT2 mutations and their biochemical consequences among a series of 59 individuals who were suspected of having CPT II deficiency based on the decreased CPT activity observed in muscle or leukocytes samples, clinical findings, or referral for mutation analysis from other laboratories. Only 19 subjects were considered to be at particularly high risk of CPT II deficiency based on review of their clinical symptoms and residual CPT activity. The samples were initially screened for 11 mutations with allele-specific oligonucleotides (ASO). Extensive sequence analysis was subsequently performed on 14 samples which either had a CPT2 mutation detected by ASO screening or the residual CPT activity was below that observed in ASO positive samples. Three known (P50H, S113L, and F448L) and three novel mutations were identified among 13 individuals in this study. A single nucleotide polymorphism was also identified 11 bp distal to the CPT2 polyadenylation site that will be useful for linkage analysis. Two of the new mutations were single nucleotide missense mutations, R503C and G549D, that occurred in highly conserved regions of the CPT isoforms, and the third was a frameshift mutation, 413 delAG, caused by a 2-bp deletion upstream of a previously identified missense mutation, F448L. The 413 delAG mutation was the second most common mutation identified in our study (20% of mutant alleles) and all individuals with the mutation were of Ashkenazi Jewish ancestry suggesting a defined ethnic origin for the mutation. Despite rigorous mutation analysis, six of 13 individuals identified with CPT2 mutations remained as heterozygotes. We propose that heterozygosity for certain CPT2 mutations, S113L and R503C, is sufficient to render individuals at risk of clinical symptoms.
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Affiliation(s)
- R T Taggart
- Department of Pediatrics, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, USA
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14
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Bruno C, Bado M, Minetti C, Cordone G, DiMauro S. Novel mutation in the CPT II gene in a child with periodic febrile myalgia and myoglobinuria. J Child Neurol 2000; 15:390-3. [PMID: 10868782 DOI: 10.1177/088307380001500607] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have identified a novel missense mutation in the carnitine palmitoyltransferase II (CPT II) gene in a child with CPT II deficiency characterized clinically by episodes of myalgia and myoglobinuria induced by intercurrent febrile illnesses. The patient was heterozygous for a G-to-A substitution at codon 487, changing an encoded glutamic acid to a lysine (E489K), while the other allele carried the common S113L mutation. This case enlarges the spectrum of mutations in patients with CPT II deficiency, and confirms the association of the S113L mutation with the muscular form.
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Affiliation(s)
- C Bruno
- Department of Pediatrics, University of Genova, Istituto Giannina Gaslini, Italy
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15
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Thuillier L, Sevin C, Demaugre F, Brivet M, Rabier D, Droin V, Aupetit J, Abadi N, Kamoun P, Saudubray JM, Bonnefont JP. Genotype/phenotype correlation in carnitine palmitoyl transferase II deficiency: lessons from a compound heterozygous patient. Neuromuscul Disord 2000; 10:200-5. [PMID: 10734268 DOI: 10.1016/s0960-8966(99)00096-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Carnitine palmitoyl transferase II deficiency, an inherited disorder of long-chain fatty acid oxidation, may result in either a mild form (muscle disease in adults) or a severe form (hepatocardiomuscular syndrome in infants). The difference in severity between these two forms is related to a difference in levels of residual carnitine palmitoyl transferase II activity and long-chain fatty acid oxidation and in genotypes. Few data are, however, available regarding compound heterozygotes for a 'mild' and a 'severe' carnitine palmitoyl transferase II mutation. We report on such a patient carrying both the 'mild' S113L substitution and the 'severe' Y628S mutation. The patient's clinical picture (cardiac arrest at 6 years) was markedly more serious than usually observed in S113L homozygotes, and suggested that 'mild'/'severe' compound heterozygosity makes patients at risk from life-threatening events. Palmitate oxidation and carnitine palmitoyl transferase II activity were lower in lymphocytes from the S113L/Y628S patient than in those from a S113L homozygote. Thus, assessment of carnitine palmitoyl transferase II mutations, long-chain fatty acid oxidation, and carnitine palmitoyl transferase II activity, may help in predicting the potential severity of the muscular form of carnitine palmitoyl transferase II deficiency.
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Affiliation(s)
- L Thuillier
- Laboratoire de Biochimie Génétique, Hôpital Necker-Enfants Malades, 149 rue de Sèvres, F-75743, Paris, France
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16
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Abstract
The metabolic myopathies are distinguished by extensive clinical and genetic heterogeneity within and between individual disorders. There are a number of explanations for the variability observed that go beyond single gene mutations or degrees of heteroplasmy in the case of mitochondrial DNA mutations. Some of the contributing factors include protein subunit interactions, tissue-specificity, modifying genetic factors, and environmental triggers. Advances in the molecular analysis of metabolic myopathies during the last decade have not only improved the diagnosis of individual disorders but also helped to characterize the contributing factors that make these disorders so complex.
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Affiliation(s)
- G D Vladutiu
- Associate Professor, Departments of Pediatrics, Neurology, and Pathology, Division of Genetics, School of Medicine and Biomedical Studies, State University of New York at Buffalo, 14209, USA.
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17
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Bonnefont JP, Demaugre F, Prip-Buus C, Saudubray JM, Brivet M, Abadi N, Thuillier L. Carnitine palmitoyltransferase deficiencies. Mol Genet Metab 1999; 68:424-40. [PMID: 10607472 DOI: 10.1006/mgme.1999.2938] [Citation(s) in RCA: 178] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carnitine palmitoyltransferase (CPT) deficiencies are common disorders of mitochondrial fatty acid oxidation. The CPT system is made up of two separate proteins located in the outer- (CPT1) and inner- (CPT2) mitochondrial membranes. While CPT2 is a ubiquitous protein, two tissue-specific CPT1 isoforms-the so-called "liver" (L) and "muscle" (M) CPT1s-have been shown to exist. Amino acid and cDNA nucleotide sequences have been identified for all of these proteins. L-CPT1 deficiency (13 families reported) presents as recurrent attacks of fasting hypoketotic hypoglycemia. Two L-CPT1 mutations have been reported to date. M-CPT1 deficiency has not been hitherto identified. CPT2 deficiency has several clinical presentations. The "benign" adult form (more than 150 families reported) is characterized by episodes of rhabdomyolysis triggered by prolonged exercise. The prevalent S113L mutation is found in about 50% of mutant alleles. The infantile-type CPT2 deficiency (10 families reported) presents as severe attacks of hypoketotic hypoglycemia, occasionally associated with cardiac damage commonly responsible for sudden death before 1 year of age. In addition to these symptoms, features of brain and kidney dysorganogenesis are frequently seen in the neonatal-onset CPT2 deficiency (13 families reported), almost always lethal during the first month of life. More than 25 CPT2 mutations (private missense or truncating mutations) have hitherto been detected. Treatment is based upon avoidance of fasting and/or exercise, a low-fat diet enriched with medium chain triglycerides and carnitine ("severe" CPT2 deficiency). Prenatal diagnosis may be offered for pregnancies at a 1/4 risk of infantile/severe-type CPT2 deficiency.
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Affiliation(s)
- J P Bonnefont
- Genetic Biochemistry Unit, CHU Necker-Enfants Malades, Paris, France.
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18
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Smail D, Gambino L, Boles C, Vladutiu GD. Rapid, Cost-effective Gene Mutation Screening for Carnitine Palmitoyltransferase II Deficiency Using Whole Blood on Filter Paper. Clin Chem 1999. [DOI: 10.1093/clinchem/45.11.2035] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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19
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Roe CR, Roe DS. Recent developments in the investigation of inherited metabolic disorders using cultured human cells. Mol Genet Metab 1999; 68:243-57. [PMID: 10527676 DOI: 10.1006/mgme.1999.2911] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Thepurpose of this paper is to share experience with our systems and review recent "in vitro" methods using intact cells (fibroblasts, amniocytes) in which entire metabolic pathways can be probed for inherited metabolic defects reflected by elevations of intermediates determined by tandem mass spectrometry, HPLC, or gas chromatography-mass spectrometry. Currently, one can explore the integrity of mitochondrial fat oxidation, peroxisomal degradation of methyl-branched fatty acids (e.g., pristanate), and the mitochondrial degradation of the branched chain amino acids (leucine, valine, and isoleucine). For many of the diseases, the specific defect can be recognized from the acylcarnitine profile resulting from incubation of the intact cells with stable-isotope-labeled precursors to the particular pathway. This approach has also been successful in identifying new inherited metabolic disorders, biochemical correlation with clinical phenotypes of individual defects, and sequential oxidation of fatty acids by peroxisomal-mitochondrial interaction.
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Affiliation(s)
- C R Roe
- Kimberly H. Courtwright & Joseph W. Summers Institute of Metabolic Disease, Baylor University Medical Center, Dallas, Texas, 75226, USA.
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20
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Martín MA, Rubio JC, De Bustos F, Del Hoyo P, Campos Y, García A, Börnstein B, Cabello A, Arenas J. Molecular analysis in Spanish patients with muscle carnitine palmitoyltransferase deficiency. Muscle Nerve 1999; 22:941-3. [PMID: 10398215 DOI: 10.1002/(sici)1097-4598(199907)22:7<941::aid-mus20>3.0.co;2-z] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The most common mutation in muscle carnitine palmitoyltransferase II (CPT II) deficiency is a missense mutation that replaces a leucine for a serine residue at amino acid position 113 of the CPT II protein (S113L). We performed molecular analysis in a group of 14 Spanish patients with CPT II deficiency from ten unrelated families. The S113L mutation was observed in 8 of the 14 patients studied. Seven patients were homozygous for the mutation, 1 patient was heterozygous, and 6 patients did not carry the mutation on either allele. Seven healthy relatives belonging to three different families carried the mutation on one allele. One patient carried the missense mutation that replaces a tyrosine for a serine at amino acid position 628 on one allele. Our data indicate that the S113L is also the most common mutation in Spanish patients with CPT II deficiency in muscle, and that further pathogenic mutations remain to be identified.
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Affiliation(s)
- M A Martín
- Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
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21
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Roe CR, Cederbaum SD, Roe DS, Mardach R, Galindo A, Sweetman L. Isolated isobutyryl-CoA dehydrogenase deficiency: an unrecognized defect in human valine metabolism. Mol Genet Metab 1998; 65:264-71. [PMID: 9889013 DOI: 10.1006/mgme.1998.2758] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A 2-year-old female was well until 12 months of age when she was found to be anemic and had dilated cardiomyopathy. Total plasma carnitine was 6 microM and acylcarnitine analysis while receiving carnitine supplement revealed an increase in the four-carbon species. Urine organic acids were normal. In vitro analysis of the mitochondrial pathways for beta oxidation, and leucine, valine, and isoleucine metabolism was performed in fibroblasts using stable isotope-labeled precursors to these pathways followed by acylcarnitine analysis by tandem mass spectrometry. 16-2H3-palmitate was metabolized normally down to the level of butyryl-CoA thus excluding SCAD deficiency. 13C6-leucine and 13C6-isoleucine were also metabolized normally. 13C5-valine incubation revealed a significant increase in 13C4-isobutyrylcarnitine without any incorporation into propionylcarnitine as is observed normally. These same precursors were also evaluated in fibroblasts with proven ETF-QO deficiency in which acyl-CoA dehydrogenase deficiencies in each of these pathways was clearly identified. These results indicate that in the human, there is an isobutyryl-CoA dehydrogenase which exists as a separate enzyme serving only the valine pathway in addition to the 2-methyl branched-chain dehydrogenase which serves both the valine and the isoleucine pathways in both rat and human.
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Affiliation(s)
- C R Roe
- Institute of Metabolic Disease, Baylor University Medical Center, Dallas, Texas.
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22
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Yang BZ, Ding JH, Dewese T, Roe D, He G, Wilkinson J, Day DW, Demaugre F, Rabier D, Brivet M, Roe C. Identification of four novel mutations in patients with carnitine palmitoyltransferase II (CPT II) deficiency. Mol Genet Metab 1998; 64:229-36. [PMID: 9758712 DOI: 10.1006/mgme.1998.2711] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Carnitine palmitoyltransferase II (CPT II) deficiency, an autosomal recessive disorder of fatty-acid oxidation, presents as three distinct phenotypes (neonatal, infantile, and adult onset). In order to investigate the molecular basis of these three phenotypes, six patients with CPT II deficiency have been studied. All six unrelated patients in this study experienced the clinical symptoms of CPT II deficiency. Three patients had the neonatal form, one had the milder infantile form, and the remaining two had the adult-onset form with "muscular" symptoms only. Their diagnoses were based upon in vitro analysis of the mitochondrial beta-oxidation pathway in fibroblasts and standard enzyme assays. We devised a method to screen the entire coding sequence and flanking splice junction of the CPT II gene. A total of six different mutations have been identified, including four novel mutations. Among them, the previously reported common mutation, S113L, was only found in 3 of 12 variant alleles. Three of the six mutations have been identified in a few unrelated patients, while the remaining three have been found in single families. This study, as well as those by others, indicates genetic heterogeneity in this disease. In addition to tabulating the mutations, the correlation of mutant genotype to clinical phenotype is briefly discussed.
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Affiliation(s)
- B Z Yang
- Kimberly H. Courtwright & Joseph W. Summers Institute of Metabolic Disease, Baylor University Medical Center, Dallas, Texas 75226, USA
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