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Zhang Y, Qiu W, Zhang H, Chen T, Xu F, Gu X, Han L. Clinical characteristics and genetic analysis of six children with carnitine palmitoyltransferase 2 deficiency. Zhejiang Da Xue Xue Bao Yi Xue Ban 2024; 53:207-212. [PMID: 38650450 PMCID: PMC11057986 DOI: 10.3724/zdxbyxb-2023-0611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Accepted: 03/11/2024] [Indexed: 04/25/2024]
Abstract
OBJECTIVES To investigate the clinical characteristic and genetic variants of children with carnitine palmitoyltransferase 2 (CPT2) deficiency. METHODS The clinical and genetic data of 6 children with CPT2 deficiency were retrospectively analyzed. The blood acylcarnitines and genetic variants were detected with tandem mass spectrometry and whole-exon gene sequencing, respectively. RESULTS There were 4 males and 2 females with a mean age of 32 months (15 d-9 years) at diagnosis. One case was asymptomatic and with normal laboratory test results, 2 had delayed onset, and 3 were of infantile type. Three cases were diagnosed at neonatal screening, and 3 cases presented with clinical manifestations of fever, muscle weakness, and increased muscle enzymes. Five children presented with decreased free carnitine and elevated levels of palmitoyl and octadecenoyl carnitines. CPT2 gene variants were detected at 8 loci in 6 children (4 harboring biallelic mutations and 2 harboring single locus mutations), including 3 known variants (p.R631C, p.T589M, and p.D255G) and 5 newly reported variants (p.F352L, p.R498L, p.F434S, p.A515P, and c.153-2A>G). It was predicted by PolyPhen2 and SIFT software that c.153-2A>G and p.F352L were suspected pathogenic variants, while p.R498L, p.F434S and p.A515P were variants of unknown clinical significance. CONCLUSIONS The clinical phenotypes of CPT2 deficiency are diverse. An early diagnosis can be facilitated by neonatal blood tandem mass spectrometry screening and genetic testing, and most patients have good prognosis after a timely diagnosis and treatment.
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Affiliation(s)
- Yan Zhang
- Department of Endocrinology, Hangzhou Children's Hospital, Hangzhou 310005, China.
| | - Wenjuan Qiu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, Shanghai 200092, China
| | - Huiwen Zhang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, Shanghai 200092, China
| | - Ting Chen
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, Shanghai 200092, China
| | - Feng Xu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, Shanghai 200092, China
| | - Xuefan Gu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, Shanghai 200092, China
| | - Lianshu Han
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai Institute for Pediatric Research, Shanghai 200092, China.
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Yazıcı H, Ak G, Çelik MY, Erdem F, Yanbolu AY, Er E, Bozacı AE, Güvenç MS, Aykut A, Durmaz A, Canda E, Uçar SK, Çoker M. Experience with carnitine palmitoyltransferase II deficiency: diagnostic challenges in the myopathic form. J Pediatr Endocrinol Metab 2024; 37:33-41. [PMID: 37925743 DOI: 10.1515/jpem-2023-0298] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 10/20/2023] [Indexed: 11/07/2023]
Abstract
OBJECTIVES Carnitine palmitoyltransferase II (CPT II) deficiency is an autosomal recessive disorder of long-chain fatty acid oxidation. Three clinical phenotypes, lethal neonatal form, severe infantile hepatocardiomuscular form, and myopathic form, have been described in CPT II deficiency. The myopathic form is usually mild and can manifest from infancy to adulthood, characterised by recurrent rhabdomyolysis episodes. The study aimed to investigate the clinical features, biochemical, histopathological, and genetic findings of 13 patients diagnosed with the myopathic form of CPT II deficiency at Ege University Hospital. METHODS A retrospective study was conducted with 13 patients with the myopathic form of CPT II deficiency. Our study considered demographic data, triggers of recurrent rhabdomyolysis attacks, biochemical metabolic screening, and molecular analysis. RESULTS Ten patients were examined for rhabdomyolysis of unknown causes. Two patients were diagnosed during family screening, and one was diagnosed during investigations due to increased liver function tests. Acylcarnitine profiles were normal in five patients during rhabdomyolysis. Genetic studies have identified a c.338C>T (p.Ser113Leu) variant homozygous in 10 patients. One patient showed a novel frameshift variant compound heterozygous with c.338C>T (p.Ser113Leu). CONCLUSIONS Plasma acylcarnitine analysis should be preferred as it is superior to DBS acylcarnitine analysis in diagnosing CPT II deficiency. Even if plasma acylcarnitine analysis is impossible, CPT2 gene analysis should be performed. Our study emphasizes that CPT II deficiency should be considered in the differential diagnosis of recurrent rhabdomyolysis, even if typical acylcarnitine elevation does not accompany it.
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Affiliation(s)
- Havva Yazıcı
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Gunes Ak
- Department of Clinical Biochemistry, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Merve Yoldas Çelik
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Fehime Erdem
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Ayse Yuksel Yanbolu
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Esra Er
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Ayse Ergül Bozacı
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Merve Saka Güvenç
- Department of Medical Genetics, Tepecik Training and Research Hospital, Izmir, Türkiye
| | - Ayca Aykut
- Department of Medical Genetics, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Asude Durmaz
- Department of Medical Genetics, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Ebru Canda
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Sema Kalkan Uçar
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
| | - Mahmut Çoker
- Department of Inborn Errors of Metabolism, Ege University Faculty of Medicine, Izmir, Türkiye
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Nalini A, Vengalil S, Polavarapu K, Preethish-Kumar V, Nashi S, Arunachal G, Chawla T, Bardhan M, Mohan D, Christopher R, Bevinahalli N, Kulanthaivelu K, Nishino I, Faruq M. Mutation spectrum of primary lipid storage myopathies. Ann Indian Acad Neurol 2022; 25:106-113. [PMID: 35342266 PMCID: PMC8954319 DOI: 10.4103/aian.aian_333_21] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 10/16/2021] [Accepted: 10/27/2021] [Indexed: 11/04/2022] Open
Abstract
Background: Lipid storage myopathies (LSM) constitute an important group of treatable myopathies. Genetic testing is essential for confirming the diagnosis and also helps in explaining phenotypic heterogeneity. The objective of this study was to describe the clinical features and genetic spectrum of LSM seen in a quaternary referral center in India. Methods: Eleven cases of suspected LSM underwent clinical, biochemical, histopathological and genetic evaluation. Tandem Mass Spectrometry and clinical exome sequencing with Sanger validation were performed. Results: All patients had exertion induced myalgia and either progressive or episodic limb girdle muscle weakness (LGMW). The age of onset ranged 10 to 31 years (mean- 21 ± 6.7y), age at presentation- 14 to 49 years (mean- 26.5 ± 9.5y). Mutations identified: ETFDH = 5, CPT2 = 3, FLAD1 = 1, ACADVL = 1, FLAD1 = 1. Dropped head syndrome was seen in two patients with ETFDH mutations. Bulbar symptoms and Beevor's sign were noted in a patient with FLAD1 variant. Novel variants were identified in seven patients. Conclusions: This is the first report on the genetic spectrum of LSM from India. LSM should be considered in patients with exertion induced myalgias, LGMW, cranial nerve involvement or dropped head syndrome. Genetic testing is essential for identification of these treatable disorders.
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Joshi PR, Zierz S. Muscle Carnitine Palmitoyltransferase II (CPT II) Deficiency: A Conceptual Approach. Molecules 2020; 25:molecules25081784. [PMID: 32295037 PMCID: PMC7221885 DOI: 10.3390/molecules25081784] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2020] [Revised: 04/08/2020] [Accepted: 04/11/2020] [Indexed: 11/16/2022] Open
Abstract
Carnitine palmitoyltransferase (CPT) catalyzes the transfer of long- and medium-chain fatty acids from cytoplasm into mitochondria, where oxidation of fatty acids takes place. Deficiency of CPT enzyme is associated with rare diseases of fatty acid metabolism. CPT is present in two subforms: CPT I at the outer mitochondrial membrane and carnitine palmitoyltransferase II (CPT II) inside the mitochondria. Deficiency of CPT II results in the most common inherited disorder of long-chain fatty acid oxidation affecting skeletal muscle. There is a lethal neonatal form, a severe infantile hepato-cardio-muscular form, and a rather mild myopathic form characterized by exercise-induced myalgia, weakness, and myoglobinuria. Total CPT activity (CPT I + CPT II) in muscles of CPT II-deficient patients is generally normal. Nevertheless, in some patients, not detectable to reduced total activities are also reported. CPT II protein is also shown in normal concentration in patients with normal CPT enzymatic activity. However, residual CPT II shows abnormal inhibition sensitivity towards malonyl-CoA, Triton X-100 and fatty acid metabolites in patients. Genetic studies have identified a common p.Ser113Leu mutation in the muscle form along with around 100 different rare mutations. The biochemical consequences of these mutations have been controversial. Hypotheses include lack of enzymatically active protein, partial enzyme deficiency and abnormally regulated enzyme. The recombinant enzyme experiments that we recently conducted have shown that CPT II enzyme is extremely thermoliable and is abnormally inhibited by different emulsifiers and detergents such as malonyl-CoA, palmitoyl-CoA, palmitoylcarnitine, Tween 20 and Triton X-100. Here, we present a conceptual overview on CPT II deficiency based on our own findings and on results from other studies addressing clinical, biochemical, histological, immunohistological and genetic aspects, as well as recent advancements in diagnosis and therapeutic strategies in this disorder.
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5
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Muscle Carnitine Palmitoyltransferase II Deficiency: A Review of Enzymatic Controversy and Clinical Features. Int J Mol Sci 2017; 18:ijms18010082. [PMID: 28054946 PMCID: PMC5297716 DOI: 10.3390/ijms18010082] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/20/2016] [Accepted: 12/28/2016] [Indexed: 11/17/2022] Open
Abstract
CPT (carnitine palmitoyltransferase) II muscle deficiency is the most common form of muscle fatty acid metabolism disorders. In contrast to carnitine deficiency, it is clinically characterized by attacks of myalgia and rhabdomyolysis without persistent muscle weakness and lipid accumulation in muscle fibers. The biochemical consequences of the disease-causing mutations are still discussed controversially. CPT activity in muscles of patients with CPT II deficiency ranged from not detectable to reduced to normal. Based on the observation that in patients, total CPT is completely inhibited by malony-CoA, a deficiency of malonyl-CoA-insensitive CPT II has been suggested. In contrast, it has also been shown that in muscle CPT II deficiency, CPT II protein is present in normal concentrations with normal enzymatic activity. However, CPT II in patients is abnormally sensitive to inhibition by malonyl-CoA, Triton X-100 and fatty acid metabolites. A recent study on human recombinant CPT II enzymes (His6-N-hCPT2 and His6-N-hCPT2/S113L) revealed that the wild-type and the S113L variants showed the same enzymatic activity. However, the mutated enzyme showed an abnormal thermal destabilization at 40 and 45 °C and an abnormal sensitivity to inhibition by malony-CoA. The thermolability of the mutant enzyme might explain why symptoms in muscle CPT II deficiency mainly occur during prolonged exercise, infections and exposure to cold. In addition, the abnormally regulated enzyme might be mostly inhibited when the fatty acid metabolism is stressed.
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6
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Topçu Y, Bayram E, Karaoğlu P, Yiş U, Kurul SH. Importance of acylcarnitine profile analysis for disorders of lipid metabolism in adolescent patients with recurrent rhabdomyolysis: Report of two cases. Ann Indian Acad Neurol 2014; 17:437-40. [PMID: 25506168 PMCID: PMC4251020 DOI: 10.4103/0972-2327.144031] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2014] [Revised: 02/12/2014] [Accepted: 03/16/2014] [Indexed: 11/06/2022] Open
Abstract
Metabolic myopathies due to disorders of lipid metabolism are a heterogeneous group of diseases. Newborns may present with hypotonia and convulsions, while progressive proximal muscle weakness or recurrent episodes of muscle weakness accompanied by rhabdomyolysis/myoglobinuria may be seen in older ages. There is little knowledge on detection of disorders of lipid metabolism by acylcarnitine profile (ACP) analysis by tandem mass spectrometry outside the neonatal period particularly in cases with recurrent rhabdomyolysis first presenting in adolescence and adulthood. Two adolescent female cases presented with episodes of rhabdomyolysis and muscle weakness. A 13-year-old patient had five episodes of rhabdomyolysis triggered by infections. Tandem mass spectrometry was normal. A 16-year-old female patient was hospitalized eight times due to recurrent rhabdomyolysis. Increased levels of C14:2, C14:1, and C14 were determined in tandem mass spectrometry. Final diagnoses were carnitine palmitoyltransferase II (CPT II) deficiency and very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency. Increased serum levels of long-chain acylcarnitine can guide to the diagnosis of lipid metabolism disorders. Serum ACP should be performed before enzyme assay and genetic studies.
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Affiliation(s)
- Yasemin Topçu
- Department of Pediatrics, Division of Pediatric Neurology, Dokuz Eylul University Medical Faculty, Izmir, Turkey
| | - Erhan Bayram
- Department of Pediatrics, Division of Pediatric Neurology, Dokuz Eylul University Medical Faculty, Izmir, Turkey
| | - Pakize Karaoğlu
- Department of Pediatrics, Division of Pediatric Neurology, Dokuz Eylul University Medical Faculty, Izmir, Turkey
| | - Uluç Yiş
- Department of Pediatrics, Division of Pediatric Neurology, Dokuz Eylul University Medical Faculty, Izmir, Turkey
| | - Semra Hız Kurul
- Department of Pediatrics, Division of Pediatric Neurology, Dokuz Eylul University Medical Faculty, Izmir, Turkey
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7
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Joshi PR, Deschauer M, Zierz S. Carnitine palmitoyltransferase II (CPT II) deficiency: genotype-phenotype analysis of 50 patients. J Neurol Sci 2013; 338:107-11. [PMID: 24398345 DOI: 10.1016/j.jns.2013.12.026] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 12/11/2013] [Accepted: 12/16/2013] [Indexed: 11/27/2022]
Abstract
Clinical, biochemical and molecular genetic data in a cohort of 50 patients with muscle CPT II deficiency are reported. Attacks of myoglobinuria occurred in 86% of patients. In 94% of patients the triggering factor was exercise. Although the myopathic form is often called the adult from, in 60% of patients, the age of onset was in childhood (1-12 years). All the patients in whom biochemical activity was measured had normal enzyme activity of total CPT I+II but the activity was significantly inhibited by malonyl-CoA and Triton. The p.S113L mutation was detected in 38/40 index patients (95%) in at least one allele. Sixty percent of index patients were homozygous for this mutation. Thirteen other mutations, all in compound heterozygote form, were also identified. There was no significant difference in ages of onset, clinical and biochemical phenotype of patients with p.S113L mutation in homozygous or compound heterozygous form. The exception was a tendency of slightly higher residual enzyme activity upon malonyl-CoA inhibition in compound heterozygotes. Phenotype was also not significantly different in patients with missense mutations on both alleles and patients with truncating mutation on one allele and missense mutation on the other allele. However, the only exception was that, attacks were triggered by fasting in almost all the patients with truncating mutations. In contrast, fasting triggered the attacks only in one third of patients with missense mutations on both alleles. The data indicate that within the muscle form of CPT II deficiency, the various genotypes have only marginal influence on the clinical and biochemical phenotype.
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Affiliation(s)
- Pushpa Raj Joshi
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany.
| | - Marcus Deschauer
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
| | - Stephan Zierz
- Department of Neurology, Martin-Luther-University Halle-Wittenberg, Halle (Saale), Germany
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8
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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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9
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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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Bartlett K, Pourfarzam M. Defects of beta-oxidation including carnitine deficiency. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2003; 53:469-516. [PMID: 12512350 DOI: 10.1016/s0074-7742(02)53017-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Affiliation(s)
- K Bartlett
- Department of Child Health, Department of Clinical Biochemistry, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 4LP, United Kingdom
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11
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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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Gempel K, Kiechl S, Hofmann S, Lochmüller H, Kiechl-Kohlendorfer U, Willeit J, Sperl W, Rettinger A, Bieger I, Pongratz D, Gerbitz KD, Bauer MF. Screening for carnitine palmitoyltransferase II deficiency by tandem mass spectrometry. J Inherit Metab Dis 2002; 25:17-27. [PMID: 11999976 DOI: 10.1023/a:1015109127986] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Mitochondrial carnitine palmitoyltransferase II (CPT II) deficiency is the most common inherited disorder of lipid metabolism in adults. Currently the routine diagnosis is based on the determination of CPT enzyme activity in muscle tissue. We have analysed the tandem mass spectra of serum acylcarnitines of nine CPT II-deficient patients. These spectra were compared to those of a cohort of 99 patients with other neuromuscular disorders and metabolic conditions supposed to cause alterations of the long-chain acylcarnitines. The spectra in CPT II deficiency showed characteristic elevations of C16:0 and C18:1 acylcarnitines while acetylcarnitine C2 was not elevated. In the present study, the ratio (C16:0+C18:1)/C2 has detected all CPT II deficiencies and discriminated them from unspecific alterations of serum acylcarnitines. The ratios of CPT II-deficient patients showed virtually no overlap with those observed in patients with other neuromuscular disorders. We suggest mass spectrometry of serum acylcarnitines as a rapid screening test that should be included early in the diagnostic work-up of patients with recurrent myoglobinuria, recurrent muscular weakness and myalgia.
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Affiliation(s)
- K Gempel
- Institute for Clinical Chemistry, Molecular Diagnostics and Mitochondrial Genetics and Munich Metabolic Disease Centre at the Academic Hospital Schwabing, Germany
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14
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Wortmann RL, Vladutiu GD. The clinical laboratory evaluation of the patient with noninflammatory myopathy. Curr Rheumatol Rep 2001; 3:310-6. [PMID: 11470050 DOI: 10.1007/s11926-001-0035-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The investigations used to diagnose an inflammatory muscle disease include history and physical examination, evaluation of serum levels of enzymes derived from skeletal muscle, electromyography, magnetic resonance imaging, and muscle histology. The evaluation of patients who may have noninflammatory myopathy includes, but is not limited to, these methods. Additional tools that may be useful include measurements of additional biochemistries, the forearm ischemic exercise test, magnetic resonance spectroscopy, and special tests on muscle tissue. Reports published in the past year have improved and expanded our understanding of the numerous noninflammatory myopathies and how these tools can be used more effectively.
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Affiliation(s)
- R L Wortmann
- Department of Internal Medicine, The University of Oklahoma College of Medicine-Tulsa, 4502 East 41st Street, Tulsa, OK, 74135, USA.
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Rubio JC, Martín MA, Del Hoyo P, Bautista J, Campos Y, Segura D, Navarro C, Ricoy JR, Cabello A, Arenas J. Molecular analysis of Spanish patients with AMP deaminase deficiency. Muscle Nerve 2000; 23:1175-8. [PMID: 10918252 DOI: 10.1002/1097-4598(200008)23:8<1175::aid-mus3>3.0.co;2-m] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We found six patients with AMPD deficiency in muscle who were homozygous for the most common mutation, Q12X in the AMPD gene (AMPD1), associated with this disease. Three patients had AMPD deficiency alone, showing a mild clinical phenotype. Two patients showed a defect of PPL in muscle, and were homozygous for the most common mutation associated with McArdle's disease, R49X in the muscle PPL gene (PYGM). In one of these patients, the clinical phenotype was more severe than usually seen in patients with McArdle's disease. The remaining patient harbored the mtDNA A3243G mutation, showing one of the usual clinical patterns associated with this mutation. We conclude that the Q12X mutation in AMPD1 may result in a mild clinical effect; that it is frequent in the Spanish population, and therefore frequently associated with other metabolic diseases; and that the effect of the association of AMPD and PPL deficiencies seems to be neutral.
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Affiliation(s)
- J C Rubio
- Centro de Investigación, Hospital Universitario 12 de Octubre, Madrid, Spain
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