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Lefèvre CR, Labarthe F, Dufour D, Moreau C, Faoucher M, Rollier P, Arnoux JB, Tardieu M, Damaj L, Bendavid C, Dessein AF, Acquaviva-Bourdain C, Cheillan D. Newborn Screening of Primary Carnitine Deficiency: An Overview of Worldwide Practices and Pitfalls to Define an Algorithm before Expansion of Newborn Screening in France. Int J Neonatal Screen 2023; 9:ijns9010006. [PMID: 36810318 PMCID: PMC9944086 DOI: 10.3390/ijns9010006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Revised: 01/24/2023] [Accepted: 01/28/2023] [Indexed: 02/04/2023] Open
Abstract
Primary Carnitine Deficiency (PCD) is a fatty acid oxidation disorder that will be included in the expansion of the French newborn screening (NBS) program at the beginning of 2023. This disease is of high complexity to screen, due to its pathophysiology and wide clinical spectrum. To date, few countries screen newborns for PCD and struggle with high false positive rates. Some have even removed PCD from their screening programs. To understand the risks and pitfalls of implementing PCD to the newborn screening program, we reviewed and analyzed the literature to identify hurdles and benefits from the experiences of countries already screening this inborn error of metabolism. In this study, we therefore, present the main pitfalls encountered and a worldwide overview of current practices in PCD newborn screening. In addition, we address the optimized screening algorithm that has been determined in France for the implementation of this new condition.
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Affiliation(s)
| | - François Labarthe
- Reference Center of Inherited Metabolic Disorders, Clocheville Hospital, 37000 Tours, France
| | - Diane Dufour
- Reference Center of Inherited Metabolic Disorders, Clocheville Hospital, 37000 Tours, France
| | | | | | - Paul Rollier
- Rennes University Hospital Center, 35033 Rennes, France
| | - Jean-Baptiste Arnoux
- Reference Center for Inborn Error of Metabolism, Department of Pediatrics, Necker-Enfants Malades Hospital, APHP, 75015 Paris, France
| | - Marine Tardieu
- Reference Center of Inherited Metabolic Disorders, Clocheville Hospital, 37000 Tours, France
| | - Léna Damaj
- Rennes University Hospital Center, 35033 Rennes, France
| | | | - Anne-Frédérique Dessein
- Metabolism and Rare Disease Unit, Department of Biochemistry and Molecular Biology, Center of Biology and Pathology, Lille University Hospital Center, 59000 Lille, France
| | - Cécile Acquaviva-Bourdain
- Center for Inherited Metabolic Disorders and Neonatal Screening, East Biology and Pathology Department, Groupement Hospitalier Est (GHE), Hospices Civils de Lyon, 69500 Bron, France
| | - David Cheillan
- Center for Inherited Metabolic Disorders and Neonatal Screening, East Biology and Pathology Department, Groupement Hospitalier Est (GHE), Hospices Civils de Lyon, 69500 Bron, France
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Chang S, Yang Y, Xu F, Ji W, Zhan X, Gao X, Chen T, Qiu W, Zhang H, Liang L, Lu D, Zhang K, Gu X, Han L. Clinical, biochemical, and molecular genetic characteristics of patients with primary carnitine deficiency identified by newborn screening in Shanghai, China. Front Genet 2022; 13:1062715. [PMID: 36568374 PMCID: PMC9772520 DOI: 10.3389/fgene.2022.1062715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/22/2022] [Indexed: 12/13/2022] Open
Abstract
Background: Primary carnitine deficiency (PCD) is an autosomal recessive disease caused by mutations in the SLC22A5 gene, which encodes the organic cation transporter 2 (OCTN2). Patients with PCD may be at risk of skeletal or cardiac myopathy, metabolic decompensation, and even sudden death. This study aimed to analyze the biochemical, clinical, and genetic characteristics of PCD patients identified by newborn screening (NBS) in Shanghai. Methods: Dried blood spot (DBS) samples of newborns were analyzed through tandem mass spectrometry (MS/MS) from January 2003 to December 2021. Newborns with low free carnitine (C0) levels were recalled. Mutation in the SLC22A5 gene was analyzed on suspected positive newborns with low C0 levels after recall. Results: 1,247,274 newborns were screened by MS/MS and 40 newborns were diagnosed with PCD, therefore the incidence of PCD in Shanghai was approximately 1:31,200. The mean C0 level in newborns with PCD was 5.37 ± 1.79 μmol/L before treatment and increased to 24.45 ± 10.87 μmol/L after treatment with L-carnitine. Twenty-three different variants were identified in the SLC22A5 gene, including 8 novel variants, of which c.51C>G (p.F17L) was the most frequent (27.27%, 18/66), followed by c.1400C>G (p.S467C) (25.76%, 17/66). Almost all the screened PCD patients were asymptomatic. Conclusion: NBS via MS/MS was a quick and efficient method for the early diagnosis of PCD. The incidence of PCD in Shanghai was 1:31,200. Eight novel variants were identified, which greatly expanded the variant spectrum of SLC22A5. MS/MS combined with genetic testing could effectively improve the diagnostic accuracy of PCD.
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Chen M, Yin Y, Liu H, Peng Y, Ye L, Luo Q, Miao J. Screening for newborn fatty acid oxidation disorders in Chongqing and the follow-up of confirmed children. Zhejiang Da Xue Xue Bao Yi Xue Ban 2022; 51:290-297. [PMID: 36207828 PMCID: PMC9511477 DOI: 10.3724/zdxbyxb-2022-0218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 05/17/2022] [Indexed: 06/16/2023]
Abstract
OBJECTIVE To investigate the incidence, clinical characteristics, gene mutations and prognosis of fatty acid oxidation disorders (FAOD) in newborns in Chongqing. METHODS Blood samples were collected from 35 374 newborns for screening of FAOD in the Neonatal Screening Center of Women and Children's Hospital of Chongqing Medical University from July 2020 to February 2022. The acylcarnitine spectrum was detected by tandem mass spectrometry, the positive children in primary screening were recalled within 2 weeks, and the diagnosis of FAOD was confirmed by urine organic acid measurement, blood biochemistry testing and genetic analysis. The confirmed children were given early intervention, treatment and followed-up. RESULTS Among 35 374 newborns, there were 267 positive children in primary screening, with a positive rate of 0.75%. Five children with FAOD were diagnosed by gene detection, with an incidence rate of 1/7075. Among them, there were 3 cases of primary carnitine deficiency (PCD, 1/11 791), 1 case of short-chain acyl-CoA dehydrogenase deficiency (SCADD, 1/35 374) and 1 case of very long-chain acyl-CoA dehydrogenase deficiency (VLCADD, 1/35 374). The c.1400C>G and c.338G>A were the common mutations of SLC22A5 gene in 3 children with PCD, while c.621G>T was a novel mutation. There were no clinical manifestations during the follow-up period in 2 children with supplementation of L-carnitine. Another child with PCD did not follow the doctor's advice of L-carnitine treatment, and had acute attack at the age of 6 months. The child recovered after treatment, and developed normally during the follow-up. The detected ACADS gene mutations were c.417G>C and c.1054G>A in child with SCADD, who showed normal intelligence and physical development without any clinical symptoms. The mutations of ACADVL gene were c.1349G>A and c.1843C>T in child with VLCADD, who showed acute attack in the neonatal period and recovered after treatment; the child was fed with milk powder rich in medium-chain fatty acids and had normal development during the follow-up. CONCLUSIONS The incidence of FAOD in Chongqing area is relatively high. PCD is the most common type, and the clinical phenotype of VLCADD is serious. After early diagnosis through neonatal screening, standardized treatment and management is followed, most of FAOD children can have good prognosis.
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Lin Y, Lin B, Chen Y, Zheng Z, Fu Q, Lin W, Zhang W. Biochemical and genetic characteristics of patients with primary carnitine deficiency identified through newborn screening. Orphanet J Rare Dis 2021; 16:503. [PMID: 34863234 PMCID: PMC8642906 DOI: 10.1186/s13023-021-02126-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 11/14/2021] [Indexed: 12/31/2022] Open
Abstract
Background Primary carnitine deficiency (PCD) is an autosomal recessive disorder of carnitine transportation that leads to impaired fatty acid oxidation. Large-scale studies on newborn screening (NBS) for PCD are limited. This study aimed to investigate the biochemical and genetic characteristics of patients with PCD detected through NBS. Results A total of 548 247 newborns were screened for PCD between January 2014 and June 2021; 1714 newborns with low free carnitine (C0) levels were called back and 49 patients were diagnosed with PCD. The latest incidence rate in Quanzhou, China, was estimated to be 1 in 11 189 newborns. NBS results showed that the 49 patients had varying degrees of decreased C0 levels, whereas seven patients exhibited normal C0 levels during the recall review. All patients harbored biallelic pathogenic variants of the SLC22A5 gene. Nineteen distinct SLC22A5 variants were detected in these 49 patients, and most of the detected variants were clustered in exons 1, 4, and 7. The top eight variants had an allele frequency of 86.73%. The most common variant was c.760C > T (p.R254*) with an allele frequency of 31.63%, followed by c.51C > G (p.F17L) (17.35%) and c.1400C > G (p.S467C) (16.33%). The C0 level of patients with the N/N genotype was significantly lower than that of the M/M group. The C0 levels of patients with genotypes of R254*/R254* and R254*/F17L were far lower than those of patients with the R254*/S467C genotype. Conclusions This study presented more than 500,000 NBS data with the latest incidence of 1:11 189 in the Quanzhou area. The SLC22A5 variant spectrum in the selected southern Chinese population has been updated. Patients with null variants were associated with low C0 levels. Combining NBS with genetic testing is critical to improve screening efficiency because patients with PCD may have normal C0 levels during NBS and recall review.
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Affiliation(s)
- Yiming Lin
- Center of Neonatal Disease Screening, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Bangbang Lin
- Administrative Office, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Yanru Chen
- Center of Neonatal Disease Screening, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Zhenzhu Zheng
- Center of Neonatal Disease Screening, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Qingliu Fu
- Center of Neonatal Disease Screening, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Weihua Lin
- Center of Neonatal Disease Screening, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China.
| | - Weifeng Zhang
- Department of Neonatology, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China.
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Tan J, Chen D, Chang R, Pan L, Yang J, Yuan D, Huang L, Yan T, Ning H, Wei J, Cai R. Tandem Mass Spectrometry Screening for Inborn Errors of Metabolism in Newborns and High-Risk Infants in Southern China: Disease Spectrum and Genetic Characteristics in a Chinese Population. Front Genet 2021; 12:631688. [PMID: 34394177 PMCID: PMC8355895 DOI: 10.3389/fgene.2021.631688] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Accepted: 07/12/2021] [Indexed: 12/28/2022] Open
Abstract
Inborn errors of metabolism (IEMs) often causing progressive and irreversible neurological damage, physical and intellectual development lag or even death, and serious harm to the family and society. The screening of neonatal IEMs by tandem mass spectrometry (MS/MS) is an effective method for early diagnosis and presymptomatic treatment to prevent severe permanent sequelae and death. A total of 111,986 healthy newborns and 7,461 hospitalized high-risk infants were screened for IEMs using MS/MS to understand the characteristics of IEMs and related gene mutations in newborns and high-risk infants in Liuzhou. Positive samples were analyzed by Sanger sequencing or next-generation sequencing. The results showed that the incidence of IEMs in newborns in the Liuzhou area was 1/3,733, and the incidence of IEMs in high-risk infants was 1/393. Primary carnitine deficiency (1/9,332), phenylketonuria (1/18,664), and isovaleric acidemia (1/37,329) ranked the highest in neonates, while citrullinemia type II ranked the highest in high-risk infants (1/1,865). Further, 56 mutations of 17 IEMs-related genes were found in 49 diagnosed children. Among these, HPD c.941T > C, CBS c.1465C > T, ACADS c.337G > A, c.1195C > T, ETFA c.737G > T, MMACHC 1076bp deletion, PCCB c.132-134delGACinsAT, IVD c.548C > T, c.757A > G, GCDH c.1060G > T, and HMGCL c.501C > G were all unreported variants. Some related hotspot mutations were found, including SLC22A5 c.51C > G, PAH c.1223G > A, IVD c.1208A > G, ACADS c.625G > A, and GCDH c.532G > A. These results show that the overall incidence of IEMs in the Liuzhou area is high. Hence, the scope of IEMs screening and publicity and education should be expanded for a clear diagnosis in the early stage of the disease.
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Affiliation(s)
- Jianqiang Tan
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Dayu Chen
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Rongni Chang
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Lizhen Pan
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Jinling Yang
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Dejian Yuan
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Lihua Huang
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Tizhen Yan
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Haiping Ning
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Jiangyan Wei
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
| | - Ren Cai
- Key Laboratory of Prevention and Control of Birth Defects, Department of Medical Genetics, Newborn Screening Center, Liuzhou Maternity and Child Health Care Hospital, Liuzhou Institute for Reproduction and Genetics, Affiliated Maternity Hospital and Affiliated Children's Hospital of Guangxi University of Science and Technology, Liuzhou, China
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Lin Y, Zhang W, Huang C, Lin C, Lin W, Peng W, Fu Q, Chen D. Increased detection of primary carnitine deficiency through second-tier newborn genetic screening. Orphanet J Rare Dis 2021; 16:149. [PMID: 33757571 PMCID: PMC7988980 DOI: 10.1186/s13023-021-01785-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 03/16/2021] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Newborn screening for primary carnitine deficiency (NBS) is commonly implemented worldwide; however, it has poor sensitivity. This study aimed to evaluate the feasibility of improving screening by including a second-tier genetic assay. RESULTS An Agena iPLEX assay was developed to identify 17 common SLC22A5 mutations in Chinese populations and was applied in NBS as a second-tier screening. From January 2017 to December 2018, 204,777 newborns were screened for PCD using tandem mass spectrometry. A total of 316 (0.15%) residual NBS-positive specimens with low free carnitine (C0) levels were subjected to this second-tier screening. The screening identified 20 screen-positive newborns who harboured biallelic mutations in theSLC22A5 gene, 99 carriers with one mutation, and 197 screen-negative newborns with no mutations. Among the 99 carriers, four newborns were found to have a second disease-causing SLC22A5mutation by further genetic analysis. Among the 197 screen-negatives were four newborns with persistently low C0 levels, and further genetic analysis revealed that one newborn had two novel SLC22A5 pathogenic variants. In total, 25 newborns were diagnosed with PCD, for a positive predictive value of 7.91% (25/316). Based on these data, we estimate the incidence of PCD in Quanzhou is estimated to be 1:8191.Thirteen distinct SLC22A5 variants were identified, and the most common was c.760C > T, with an allelic frequency of 32% (16/50), followed by c.1400C > G (7/50, 14%), and c.51C > G (7/50, 14%). CONCLUSION Data from this study revealed that 24% (6/25) of PCD cases would have been missed by conventional NBS. This high-throughput iPLEX assay is a powerful tool for PCD genotyping. The addition of this second-tier genetic screening to the current NBS program could identify missed PCD cases, thereby increasing PCD detection. However, further studies are needed to optimise the workflow of the new screening algorithm and to evaluate the cost-effectiveness of this screening approach.
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Affiliation(s)
- Yiming Lin
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Weifeng Zhang
- Department of Neonatal Intensive Care Unit, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Chenggang Huang
- Zhejiang Biosan Biochemical Technologies Co., Ltd, Hangzhou, China
| | - Chunmei Lin
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Weihua Lin
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Weilin Peng
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Qingliu Fu
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China.
| | - Dongmei Chen
- Department of Neonatal Intensive Care Unit, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China.
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Chen Y, Lin Q, Zeng Y, Qiu X, Liu G, Zhu W. Gene spectrum and clinical traits of 10 patients with primary carnitine deficiency. Mol Genet Genomic Med 2021; 9:e1583. [PMID: 33560599 PMCID: PMC8077093 DOI: 10.1002/mgg3.1583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 10/26/2020] [Accepted: 11/17/2020] [Indexed: 11/07/2022] Open
Abstract
BACKGROUND Rare studies focused on the tandem mass spectrometry (MS/MS) findings for the primary carnitine deficiency (PCD) in the neonates in China mainland. In this study, we aim to analyze the gene mutation spectrum of PCD in Fujian Province in China mainland. METHODS Primary carnitine deficiency (PCD) samples used in this study were selected from 95,453 cases underwent neonatal screening between May 2015 and February 2020. SLC22A5 gene sequencing was performed on the neonates and their parents with C0 level of less than 8.8 μmol/L. RESULTS Ten patients (male: 7; female: 3) were finally included in this study. Among these patients, nine were neonates, and one was maternal decline of C0 of less than 8.8 μmol/L. The maternal case showed two types of mutations of SLC22A5 including c.760C>T(p.R254*) and c.1400C>G(p.S467C). The other nine neonates showed compound mutations involving nine types in 18 sites, among which two mutations [i.e., c.37G>T(p.E13*) and c.694A>G(p.T232A)] were novel that had never been reported before. Bioinformatic analysis indicated that c.37G>T(p.E13*) was a pathogenic mutation, while the c.694A>G (p.T232A) was considered to be likely pathogenic. CONCLUSION MS/MS screening on PCD contributed to the early diagnosis and screening. In addition, SLC22A5 gene mutation analysis contributed to the PCD screening.
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Affiliation(s)
- Yao Chen
- Neonatal Screening Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Qingying Lin
- Neonatal Screening Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Yinglin Zeng
- Neonatal Screening Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Xiaolong Qiu
- Neonatal Screening Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Guanghua Liu
- Department of Pediatrics, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, China
| | - Wenbin Zhu
- Neonatal Screening Center, Fujian Maternity and Child Health Hospital, Affiliated Hospital of Fujian Medical University, Fuzhou, China
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Lin W, Wang K, Zheng Z, Chen Y, Fu C, Lin Y, Chen D. Newborn screening for primary carnitine deficiency in Quanzhou, China. Clin Chim Acta 2020; 512:166-171. [PMID: 33181153 DOI: 10.1016/j.cca.2020.11.005] [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: 09/02/2020] [Revised: 11/03/2020] [Accepted: 11/03/2020] [Indexed: 02/06/2023]
Abstract
BACKGROUND AND AIMS Primary carnitine deficiency (PCD) is an autosomal recessive disease caused by functional defects in the carnitine transporter OCTN2 due to mutations in SLC22A5. Here, we aimed to understand the incidence, clinical, biochemical, and molecular features of PCD in Quanzhou, China. MATERIALS AND METHODS Newborn screening (NBS) was performed through tandem mass spectrometry (MS/MS) to detect genetic metabolic diseases. Next-generation sequencing was used to detect SLC22A5 mutations in patients with suspected PCD. RESULTS From 364,545 newborns screened, 36 were diagnosed with PCD, in addition to five mothers. The incidence of PCD in children in the Quanzhou area was 1:10126. Eighteen SLC22A5 variants were found, with five novel ones. The most prevalent variant in neonatal and maternal patients was c.760C > T (p.R254*). Twenty-five neonatal patients received L-carnitine supplementation; however, one patient discontinued treatment and sudden death occurred. One sibling presented repeated fatigue, hypoglycemia, and coma, but the symptoms disappeared after treatment. Two mothers with PCD claimed to feel weak and easily fatigued. CONCLUSION The incidence of PCD is relatively high in the Quanzhou area. Five novel variants were found, broadening the mutation spectrum of SLC22A5. NBS is effective in identifying PCD, and sudden death may be prevented with timely treatment.
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Affiliation(s)
- Weihua Lin
- Department of Child Health Care, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province 362000, China
| | - Kunyi Wang
- Integrated Technical Service Center, Quanzhou Customs, Quanzhou, Fujian Province 362000, China
| | - Zhenzhu Zheng
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province 362000, China
| | - Yanru Chen
- Department of Child Health Care, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province 362000, China
| | - Caifeng Fu
- Department of Child Health Care, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province 362000, China
| | - Yiming Lin
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province 362000, China.
| | - Dongmei Chen
- Newborn ICU, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province 362000, China.
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Lin Y, Lin W, Chen Y, Lin C, Zheng Z, Zhuang J, Fu Q. Combined primary carnitine deficiency with neonatal intrahepatic cholestasis caused by citrin deficiency in a Chinese newborn. BMC Pediatr 2020; 20:478. [PMID: 33050909 PMCID: PMC7552534 DOI: 10.1186/s12887-020-02372-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 10/06/2020] [Indexed: 12/23/2022] Open
Abstract
Background Primary carnitine deficiency (PCD) is an autosomal recessive disorder affecting the carnitine cycle and resulting in defective fatty acid oxidation. Neonatal intrahepatic cholestasis caused by citrin deficiency (NICCD) is an autosomal recessive disorder and one of the main causes of inherited neonatal cholestasis. Both PCD and NICCD are included in the current expanded newborn screening (NBS) targets. Case presentation Targeted exome sequencing was performed on a Chinese proband, and Sanger sequencing was utilised to validate the detected mutations. The patient who was initially suspected to have PCD based on the NBS results presented with neonatal intrahepatic cholestasis and ventricular septal defect. Further investigations not only confirmed PCD but also revealed the presence of NICCD. Four distinct mutations were detected, including c.51C > G (p.F17L) and c.760C > T (p.R254X) in SLC22A5 as well as c.615 + 5G > A and IVS16ins3kb in SLC25A13. Conclusions This is the first reported case of PCD and NICCD occurring in the same patient. The dual disorders in a newborn broaden our understanding of inherited metabolic diseases. Thus, this study highlighted the importance of further genetic testing in patients presenting with unusual metabolic screening findings.
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Affiliation(s)
- Yiming Lin
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Weihua Lin
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Yanru Chen
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Chunmei Lin
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Zhenzhu Zheng
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China
| | - Jianlong Zhuang
- Prenatal Diagnosis Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China.
| | - Qingliu Fu
- Neonatal Disease Screening Center, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, 362000, Fujian Province, China.
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10
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Luo X, Sun Y, Xu F, Guo J, Li L, Lin Z, Ye J, Gu X, Yu Y. A pilot study of expanded newborn screening for 573 genes related to severe inherited disorders in China: results from 1,127 newborns. ANNALS OF TRANSLATIONAL MEDICINE 2020; 8:1058. [PMID: 33145277 PMCID: PMC7575988 DOI: 10.21037/atm-20-1147] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Background Newborn screening (NBS) in China is mainly aimed at detecting biochemical levels of metabolites in the blood, which may generate false-positive/negative results. Current biochemical NBS includes tandem mass spectrometry (MS/MS) screening for metabolites as well as phenylalanine (Phe), thyroid-stimulating hormone (TSH), 17-α-hydroxyprogesterone (17-OHP), and glucose-6-phosphate dehydrogenase (G6PD) test. This study intended to explore whether next-generation sequencing (NGS) for dried blood spots combining with biochemical screening could improve the current screening efficiency and to investigate the carrier frequencies of mutations in causative genes related to amino acid metabolism, organic acid metabolism, and fatty acid oxidation in this cohort. Methods We designed a panel of 573 genes related to severe inherited disorders and performed NGS in 1,127 individuals who had undergone biochemical NBS. The NGS screening results of neonates were used to compare with the biochemical results. Results NGS screening results revealed that all the four newborns with abnormal G6PD values carried hemizygous G6PD mutations, which were consistent with the decreased G6PD enzymatic activity. The NGS results revealed an individual with compound heterozygous mutations of SLC22A5, who was biochemically negative in 2016. The MS/MS screening results in 2019 showed free carnitine deficiency, which was consistent with the genetic findings. The top five genes with the highest carrier frequencies of mutations in these newborns were PAH (1:56, 1.79%), ETFDH (1:81, 1.23%), MMACHC (1:87, 1.15%), SLC25A13 (1:102, 0.98%), and GCDH (1:125, 0.80%). Conclusions Our study highlighted that combining NGS screening with biochemical screening could improve the current NBS efficiency. This is the first study to investigate carrier frequencies of mutations in 77 genes causing inherited metabolic diseases (IMDs) in China.
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Affiliation(s)
- Xiaomei Luo
- Department of Pediatric Endocrinology and Genetics, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yu Sun
- Department of Pediatric Endocrinology and Genetics, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Feng Xu
- Department of Pediatric Endocrinology and Genetics, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jun Guo
- Department of Pediatric Endocrinology and Genetics, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lin Li
- Nanjing Novogene Bio Technology Co., Ltd., Nanjing, China
| | - Zhiwei Lin
- Nanjing Novogene Bio Technology Co., Ltd., Nanjing, China
| | - Jun Ye
- Department of Pediatric Endocrinology and Genetics, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xuefan Gu
- Department of Pediatric Endocrinology and Genetics, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yongguo Yu
- Department of Pediatric Endocrinology and Genetics, Shanghai Institute for Pediatric Research, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.,Shanghai Key Laboratory of Pediatric Gastroenterology and Nutrition, Shanghai, China
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11
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Screening 3.4 million newborns for primary carnitine deficiency in Zhejiang Province, China. Clin Chim Acta 2020; 507:199-204. [PMID: 32371215 DOI: 10.1016/j.cca.2020.04.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/31/2022]
Abstract
Testing for primary carnitine deficiency (PCD) has been implemented in many newborn screening (NBS) programs, but few large-scale studies on NBS for PCD have been reported in China. This study aimed to assess the incidence and biochemical, clinical, and genetic characteristics of PCD discovered by NBS. Dried blood spots from newborns were analyzed by tandem mass spectrometry (MS/MS) and suspected positive patients were further tested using molecular genetic analysis. Infants who carried two variants in SLC22A5 or those with extremely low free carnitine levels during recall were referred for follow-up and treatment. Over 3.4 million newborns were screened and 113 newborns were diagnosed with PCD, yielding a positive predictive value of 1.93%. In addition, 63 mothers with PCD were identified. The incidence of PCD in newborns and mothers in Zhejiang was 1:30,182 and 1:54,137, respectively. Thirty-seven distinct variants were identified in SLC22A5 of which 10 were novel. c.1400C > G (p.S467C) was the most prevalent variant in both newborns and mothers with PCD, while c.760C > T (p.R254*), which is reportedly common in other Chinese regions, was rarely detected in maternal PCD patients. This study reports the largest series of patients with PCD detected by NBS and identifies 10 novel variants, expanding the variant spectrum of SLC22A5.
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12
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Zhang Y, Li H, Liu J, Yan H, Liu Q, Wei X, Xi H, Jia Z, Wu L, Wang H. Molecular investigation in Chinese patients with primary carnitine deficiency. Mol Genet Genomic Med 2019; 7:e901. [PMID: 31364285 PMCID: PMC6732302 DOI: 10.1002/mgg3.901] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 07/15/2019] [Accepted: 07/17/2019] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Primary carnitine deficiency (PCD) is an autosomal recessive disorder of carnitine transportation caused by mutations in the SLC22A5 that lead to low serum carnitine levels and decreased intracellular carnitine accumulation. Characteristic clinical findings are hypoketotic hypoglycemia and skeletal and cardiac myopathy. OBJECTIVE To genetically diagnose 24 unrelated Chinese patients with PCD, including 18 infants and six adults. METHODS The entire coding region and the intron-exon boundaries of SLC22A5 were amplified by polymerase chain reaction (PCR). In silico analyses and reverse transcription-polymerase chain reaction (RT-PCR) were used to predict variants' impact on protein structure and function. RESULTS Disease-causing variants in the SLC22A5 were identified in all 24 subjects, and c.288delG, c.495C>A, c.774_775insTCG, c.824+1G>A, and c.1418G>T were novel. The novel variant c.824+1G>A caused a truncated protein p.Phe276Tyrfs*8. CONCLUSIONS We identified 13 variants in the SLC22A5 in 24 PCD patients, and five of these variants are novel mutations. c.824+1G>A was confirmed to alter mRNA splicing by reverse transcription PCR. Furthermore, our findings broaden the mutation spectrum of SLC22A5 and the understanding of the diverse and variable effects of PCD variants.
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Affiliation(s)
- Yanghui Zhang
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China.,NHC Key Laboratory of Birth Defects Research, Prevention and Treatment (Hunan Provincial Maternal and Child Health Care Hospital), Changsha, Hunan, China
| | - Haoxian Li
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China.,NHC Key Laboratory of Birth Defects Research, Prevention and Treatment (Hunan Provincial Maternal and Child Health Care Hospital), Changsha, Hunan, China
| | - Jing Liu
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China.,NHC Key Laboratory of Birth Defects Research, Prevention and Treatment (Hunan Provincial Maternal and Child Health Care Hospital), Changsha, Hunan, China
| | - Huiming Yan
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China.,NHC Key Laboratory of Birth Defects Research, Prevention and Treatment (Hunan Provincial Maternal and Child Health Care Hospital), Changsha, Hunan, China
| | - Qin Liu
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China.,NHC Key Laboratory of Birth Defects Research, Prevention and Treatment (Hunan Provincial Maternal and Child Health Care Hospital), Changsha, Hunan, China
| | - Xianda Wei
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Jinan, Shandong, China
| | - Hui Xi
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China.,NHC Key Laboratory of Birth Defects Research, Prevention and Treatment (Hunan Provincial Maternal and Child Health Care Hospital), Changsha, Hunan, China
| | - Zhengjun Jia
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China.,NHC Key Laboratory of Birth Defects Research, Prevention and Treatment (Hunan Provincial Maternal and Child Health Care Hospital), Changsha, Hunan, China
| | - Lingqian Wu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, China
| | - Hua Wang
- Hunan Provincial Maternal and Child Health Care Hospital, Changsha, Hunan, China.,NHC Key Laboratory of Birth Defects Research, Prevention and Treatment (Hunan Provincial Maternal and Child Health Care Hospital), Changsha, Hunan, China
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13
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SLC22A5 Mutations in a Patient With Systemic Primary Carnitine Deficiency and Cleft Palate-Successful Perioperative Management. J Craniofac Surg 2018; 29:1601-1603. [DOI: 10.1097/scs.0000000000004595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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14
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Frigeni M, Balakrishnan B, Yin X, Calderon FRO, Mao R, Pasquali M, Longo N. Functional and molecular studies in primary carnitine deficiency. Hum Mutat 2017; 38:1684-1699. [PMID: 28841266 DOI: 10.1002/humu.23315] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 08/13/2017] [Accepted: 08/17/2017] [Indexed: 12/30/2022]
Abstract
Primary carnitine deficiency is caused by a defect in the OCTN2 carnitine transporter encoded by the SLC22A5 gene. It can cause hypoketotic hypoglycemia or cardiomyopathy in children, and sudden death in children and adults. Fibroblasts from affected patients have reduced carnitine transport. We evaluated carnitine transport in fibroblasts from 358 subjects referred for possible carnitine deficiency. Carnitine transport was reduced to 20% or less of normal in fibroblasts of 140 out of 358 subjects. Sequencing of the 10 exons and flanking regions of the SLC22A5 gene in 95 out of 140 subjects identified causative variants in 84% of the alleles. The missense variants identified in our patients and others previously reported (n = 92) were expressed in CHO cells. Carnitine transport was impaired by 73 out of 92 variants expressed. Prediction algorithms (Polyphen-2, SIFT) correctly predicted the functional effects of expressed variants in about 80% of cases. These results indicate that mutations in the coding region of the SLC22A5 gene cannot be identified in about 16% of the alleles causing primary carnitine deficiency. Prediction algorithms failed to determine the functional effects of amino acid substitutions in this transmembrane protein in about 20% of cases. Therefore, functional studies in fibroblasts remain the best strategy to confirm or exclude a diagnosis of primary carnitine deficiency.
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Affiliation(s)
- Marta Frigeni
- Division of Medical Genetics/Pediatrics, University of Utah, Salt Lake City, Utah
| | - Bijina Balakrishnan
- Division of Medical Genetics/Pediatrics, University of Utah, Salt Lake City, Utah
| | - Xue Yin
- Division of Medical Genetics/Pediatrics, University of Utah, Salt Lake City, Utah
| | - Fernanda R O Calderon
- ARUP Institute for Clinical and Experimental Pathology®, ARUP Laboratories, Salt Lake City, Utah.,Department of Pathology, University of Utah, Salt Lake City, Utah
| | - Rong Mao
- ARUP Institute for Clinical and Experimental Pathology®, ARUP Laboratories, Salt Lake City, Utah.,Department of Pathology, University of Utah, Salt Lake City, Utah
| | - Marzia Pasquali
- Division of Medical Genetics/Pediatrics, University of Utah, Salt Lake City, Utah.,ARUP Institute for Clinical and Experimental Pathology®, ARUP Laboratories, Salt Lake City, Utah.,Department of Pathology, University of Utah, Salt Lake City, Utah
| | - Nicola Longo
- Division of Medical Genetics/Pediatrics, University of Utah, Salt Lake City, Utah.,ARUP Institute for Clinical and Experimental Pathology®, ARUP Laboratories, Salt Lake City, Utah.,Department of Pathology, University of Utah, Salt Lake City, Utah
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15
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Genetic basis of dilated cardiomyopathy. Int J Cardiol 2016; 224:461-472. [PMID: 27736720 DOI: 10.1016/j.ijcard.2016.09.068] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 09/15/2016] [Accepted: 09/17/2016] [Indexed: 01/19/2023]
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16
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Longo N, Frigeni M, Pasquali M. Carnitine transport and fatty acid oxidation. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2016; 1863:2422-35. [PMID: 26828774 DOI: 10.1016/j.bbamcr.2016.01.023] [Citation(s) in RCA: 454] [Impact Index Per Article: 56.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 01/27/2016] [Accepted: 01/28/2016] [Indexed: 12/14/2022]
Abstract
Carnitine is essential for the transfer of long-chain fatty acids across the inner mitochondrial membrane for subsequent β-oxidation. It can be synthesized by the body or assumed with the diet from meat and dairy products. Defects in carnitine biosynthesis do not routinely result in low plasma carnitine levels. Carnitine is accumulated by the cells and retained by kidneys using OCTN2, a high affinity organic cation transporter specific for carnitine. Defects in the OCTN2 carnitine transporter results in autosomal recessive primary carnitine deficiency characterized by decreased intracellular carnitine accumulation, increased losses of carnitine in the urine, and low serum carnitine levels. Patients can present early in life with hypoketotic hypoglycemia and hepatic encephalopathy, or later in life with skeletal and cardiac myopathy or sudden death from cardiac arrhythmia, usually triggered by fasting or catabolic state. This disease responds to oral carnitine that, in pharmacological doses, enters cells using the amino acid transporter B(0,+). Primary carnitine deficiency can be suspected from the clinical presentation or identified by low levels of free carnitine (C0) in the newborn screening. Some adult patients have been diagnosed following the birth of an unaffected child with very low carnitine levels in the newborn screening. The diagnosis is confirmed by measuring low carnitine uptake in the patients' fibroblasts or by DNA sequencing of the SLC22A5 gene encoding the OCTN2 carnitine transporter. Some mutations are specific for certain ethnic backgrounds, but the majority are private and identified only in individual families. Although the genotype usually does not correlate with metabolic or cardiac involvement in primary carnitine deficiency, patients presenting as adults tend to have at least one missense mutation retaining residual activity. This article is part of a Special Issue entitled: Mitochondrial Channels edited by Pierre Sonveaux, Pierre Maechler and Jean-Claude Martinou.
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Affiliation(s)
- Nicola Longo
- Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, UT, USA; Department of Pathology, University of Utah, and ARUP Laboratories, 500 Chipeta Way, Salt Lake City, UT, USA.
| | - Marta Frigeni
- Division of Medical Genetics, Department of Pediatrics, University of Utah, Salt Lake City, UT, USA
| | - Marzia Pasquali
- Department of Pathology, University of Utah, and ARUP Laboratories, 500 Chipeta Way, Salt Lake City, UT, USA
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17
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Inherited metabolic diseases in the Southern Chinese population: spectrum of diseases and estimated incidence from recurrent mutations. Pathology 2015; 46:375-82. [PMID: 24992243 DOI: 10.1097/pat.0000000000000140] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Inherited metabolic diseases (IMDs) are a large group of rare genetic diseases. The spectrum and incidences of IMDs differ among populations, which has been well characterised in Caucasians but much less so in Chinese. In a setting of a University Hospital Metabolic Clinic in Hong Kong, over 100 patients with IMDs have been seen during a period of 13 years (from 1997 to 2010). The data were used to define the spectrum of diseases in the Southern Chinese population. Comparison with other populations revealed a unique spectrum of common IMDs. Furthermore, the incidence of the common IMDs was estimated by using population carrier frequencies of known recurrent mutations. Locally common diseases (their estimated incidence) include (1) glutaric aciduria type 1 (∼1/60,000), (2) multiple carboxylase deficiency (∼1/60,000), (3) primary carnitine deficiency (∼1/60,000), (4) carnitine-acylcarnitine translocase deficiency (∼1/60,000), (5) glutaric aciduria type 2 (∼1/22,500), (6) citrin deficiency (∼1/17,000), (7) tetrahydrobiopterin-deficient hyperphenylalaninaemia due to 6-pyruvoyl-tetrahydropterin synthase deficiency (∼1/60,000), (8) glycogen storage disease type 1 (∼1/150,000). In addition, ornithine carbamoyltransferase deficiency and X-linked adrenoleukodystrophy are common X-linked diseases. Findings of the disease spectrum and treatment outcome are summarised here which may be useful for clinical practice. In addition, data will also be useful for policy makers in planning of newborn screening programs and resource allocation.
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18
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Han L, Wang F, Wang Y, Ye J, Qiu W, Zhang H, Gao X, Gong Z, Gu X. Analysis of genetic mutations in Chinese patients with systemic primary carnitine deficiency. Eur J Med Genet 2014; 57:571-5. [PMID: 25132046 DOI: 10.1016/j.ejmg.2014.08.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Accepted: 08/01/2014] [Indexed: 12/30/2022]
Abstract
Systemic primary carnitine deficiency (CDSP) is caused by mutations in SLC22A5 gene, which encodes organic cation transporter 2(OCTN2). CDSP leads to skeletal or cardiac myopathy and hepatic encephalopathy. The present study aimed to identify SLC22A5 gene mutations and analyze the potential relationship between genotype and clinical symptoms in 20 Chinese patients with CDSP. The complete coding region of the SLC22A5 gene including intron-exon boundaries were amplified and sequenced in all patients. Eighteen different mutations were found; of which, nine were novel. The mutations clustering in exons 1 and 4 accounted for 66.7% of all mutant alleles (26/39). The c.760C>T (p. R254X) was the most frequent mutation (25.6%, 10/39), suggesting it as an ethnic founder mutation. The relationship between genotype and phenotype was investigated in patients carrying the R254X mutation. Homozygous patients with R254X were late-onset cases who presented with dilated cardiomyopathy and muscle weakness after 1 year of age. Compound heterozygous patients carrying R254X, combined with other missense mutations occurred in very specific positions, dramatically altered OCTN2 protein function. Based on the analysis of case studies, a clear relationship between free carnitine (C0) level in plasma and OCTN2 genotype was not found in the present work, however, the low plasma C0 level could not indicate disease severity or genotype. Further functional studies with a large sample size are required to understand the relationship between R254X mutation and CDSP.
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Affiliation(s)
- Lianshu Han
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Fei Wang
- Department of Pediatric Endocrinology, Children's Hospital, Shanghai Jiaotong University, Shanghai 200040, China
| | - Yu Wang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Jun Ye
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Wenjuan Qiu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Huiwen Zhang
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Xiaolan Gao
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Zhuwen Gong
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China
| | - Xuefan Gu
- Department of Pediatric Endocrinology and Genetic Metabolism, Xinhua Hospital, Shanghai Institute for Pediatric Research, Shanghai Jiaotong University School of Medicine, Shanghai 200092, China.
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19
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Qu Q, Qu J, Zhan M, Wu LX, Zhang YW, Lou XY, Fu LJ, Zhou HH. Different involvement of promoter methylation in the expression of organic cation/carnitine transporter 2 (OCTN2) in cancer cell lines. PLoS One 2013; 8:e76474. [PMID: 24146874 PMCID: PMC3797819 DOI: 10.1371/journal.pone.0076474] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 08/29/2013] [Indexed: 01/12/2023] Open
Abstract
Organic cation/carnitine transporter 2 (OCTN2) is responsible for the cellular uptake of the antineoplastic agent, oxaliplatin. Epigenetic modification is a possible mechanism of altered drug-transporter expression in cancers, leading to altered efficacy of chemotherapeutic drugs. However, the mechanisms governing OCTN2 regulation are not completely understood. In this study, the low levels of OCTN2 in HepG2 and LS174T cells were elevated by the demethylating reagent, decitabine (DCA). To further reveal the epigenetic mechanism of down-regulation of OCTN2, we found that Region-1 within the OCTN2 promoter (spanning −354 to +85) was a determinant of OCTN2 expression in a luciferase reporter assay. Moreover, methylation-specific PCR (MSP) and bisulfite genomic sequencing showed that the degree of individual methylated CpG sites within this region was inversely correlated with the levels of OCTN2 in different cancer cells. Application of DCA to HepG2 and LS174T cells reversed the hypermethylation status of the OCTN2 promoter and increased OCTN2 expression, enhancing cellular uptake of oxaliplatin. Thus, we identified that promoter methylation is responsible for epigenetic down-regulation of OCTN2 in HepG2 and LS174T cells. Given the essential role of OCTN2 in cancer cell uptake of chemotherapeutics, and thus treatment efficacy, pretreatment with a demethylating reagent is a possible strategy for optimizing pharmacotherapies against cancers.
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Affiliation(s)
- Qiang Qu
- Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Jian Qu
- Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Min Zhan
- Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Lan-Xiang Wu
- Institute of Life Sciences, Chongqing Medical University, Chongqing, China
| | - Yi-Wen Zhang
- Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Xiao-Ya Lou
- Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
| | - Li-Juan Fu
- Institute of Life Sciences, Chongqing Medical University, Chongqing, China
| | - Hong-Hao Zhou
- Institute of Clinical Pharmacology, Hunan Key Laboratory of Pharmacogenetics, Xiangya School of Medicine, Central South University, Changsha, Hunan, China
- * E-mail:
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20
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Chen YC, Chien YH, Chen PW, Leung-Sang Tang N, Chiu PC, Hwu WL, Lee NC. Carnitine uptake defect (primary carnitine deficiency): risk in genotype-phenotype correlation. Hum Mutat 2013; 34:655. [PMID: 23520115 DOI: 10.1002/humu.22286] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2012] [Accepted: 12/11/2012] [Indexed: 11/11/2022]
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21
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Chien YH, Lee NC, Chao MC, Chen LC, Chen LH, Chien CC, Ho HC, Suen JH, Hwu WL. Fatty Acid oxidation disorders in a chinese population in taiwan. JIMD Rep 2013; 11:165-72. [PMID: 23700290 PMCID: PMC3755561 DOI: 10.1007/8904_2013_236] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/14/2013] [Revised: 04/14/2013] [Accepted: 04/25/2013] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Fatty acid oxidation (FAO) disorders are a heterogeneous group of inborn errors in the transportation and oxidation of fatty acids. FAO disorders were thought to be very rare in the Chinese population. Newborn screening for FAO disorders beginning in 2002 in Taiwan may have increased the diagnosis of this group of diseases. MATERIALS AND METHODS Till 2012, the National Taiwan University Hospital Newborn Screening Center screened more than 800,000 newborns for FAO disorders. Both patients diagnosed through screening and patients detected after clinical manifestations were included in this study. RESULTS A total of 48 patients with FAO disorders were identified during the study period. The disorders included carnitine palmitoyltransferase I deficiency, carnitine acylcarnitine translocase deficiency, carnitine palmitoyltransferase II deficiency, very long-chain acyl-CoA dehydrogenase deficiency, medium-chain acyl-CoA dehydrogenase deficiency, multiple acyl-CoA dehydrogenase deficiency, short-chain defects, and carnitine uptake defect. Thirty-nine patients were diagnosed through newborn screening. Five false-negative newborn screening cases were noted during this period, and four patients who were not screened were diagnosed based on clinical manifestations. The ages of all patients ranged from 6 months to 22.9 years (mean age 6.6 years). Except for one case of postmortem diagnosis, there were no other mortalities. CONCLUSIONS The combined incidence of FAO disorders estimated by newborn screening in the Chinese population in Taiwan is 1 in 20,271 live births. Newborn screening also increases the awareness of FAO disorders and triggers clinical diagnoses of these diseases.
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Affiliation(s)
- Yin-Hsiu Chien
- />Department of Medical Genetics and Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
| | - Ni-Chung Lee
- />Department of Medical Genetics and Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
| | - Mei-Chyn Chao
- />Division of Genetics, Endocrinology and Metabolism, Department of Pediatrics, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan
- />Department of Genome Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan
| | - Li-Chu Chen
- />Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Li-Hsin Chen
- />Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Chun-Ching Chien
- />Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
| | - Hui-Chen Ho
- />Taipei Institute of Pathology, Taipei, Taiwan
| | | | - Wuh-Liang Hwu
- />Department of Medical Genetics and Pediatrics, National Taiwan University Hospital, Taipei, Taiwan
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22
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Shibbani K, Fahed AC, Al-Shaar L, Arabi M, Nemer G, Bitar F, Majdalani M. Primary carnitine deficiency: novel mutations and insights into the cardiac phenotype. Clin Genet 2013; 85:127-37. [PMID: 23379544 DOI: 10.1111/cge.12112] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 01/22/2013] [Indexed: 11/28/2022]
Abstract
Solute carrier family 22 member 5 (SLC22A5) encodes a sodium-dependent ion transporter responsible for shuffling carnitine across the plasma membrane. This process provides energy for the heart, among other organs allowing beta-oxidation of fatty acids. Mutations in SLC22A5 result in primary carnitine deficiency (PCD), a disorder that manifests with cardiac, skeletal, or metabolic symptoms. We hereby describe two novel mutations in SLC22A5 in two Lebanese families associated exclusively with a cardiac phenotype. The frequency of the cardiac, metabolic and skeletal symptoms in PCD patients remains undefined. All the reported eight PCD patients belonging to five different Lebanese families have an exclusive cardiac phenotype. Carnitine levels appear to be directly linked to the type and position of the mutation and the severity of the phenotypic presentation does not seem to be associated with serum carnitine levels. A comprehensive review of 61 literature-reported PCD cases revealed an exclusive cardiac manifestation frequency at 62.3% with a very low likelihood of simultaneous occurrence of cardiac and metabolic manifestation.
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Affiliation(s)
- K Shibbani
- Department of Biochemistry and Molecular Genetics, American University of Beirut, Beirut, Lebanon
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Wang LY, Chen NI, Chen PW, Chiang SC, Hwu WL, Lee NC, Chien YH. Newborn screening for citrin deficiency and carnitine uptake defect using second-tier molecular tests. BMC MEDICAL GENETICS 2013; 14:24. [PMID: 23394329 PMCID: PMC3575349 DOI: 10.1186/1471-2350-14-24] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 02/07/2013] [Indexed: 11/26/2022]
Abstract
Background Tandem mass spectrometry (MS/MS) analysis is a powerful tool for newborn screening, and many rare inborn errors of metabolism are currently screened using MS/MS. However, the sensitivity of MS/MS screening for several inborn errors, including citrin deficiency (screened by citrulline level) and carnitine uptake defect (CUD, screened by free carnitine level), is not satisfactory. This study was conducted to determine whether a second-tier molecular test could improve the sensitivity of citrin deficiency and CUD detection without increasing the false-positive rate. Methods Three mutations in the SLC25A13 gene (for citrin deficiency) and one mutation in the SLC22A5 gene (for CUD) were analyzed in newborns who demonstrated an inconclusive primary screening result (with levels between the screening and diagnostic cutoffs). Results The results revealed that 314 of 46 699 newborns received a second-tier test for citrin deficiency, and two patients were identified; 206 of 30 237 newborns received a second-tier testing for CUD, and one patient was identified. No patients were identified using the diagnostic cutoffs. Although the incidences for citrin deficiency (1:23 350) and CUD (1:30 000) detected by screening are still lower than the incidences calculated from the mutation carrier rates, the second-tier molecular test increases the sensitivity of newborn screening for citrin deficiency and CUD without increasing the false-positive rate. Conclusions Utilizing a molecular second-tier test for citrin deficiency and carnitine transporter deficiency is feasible.
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Affiliation(s)
- Li-Yun Wang
- Graduate Institute of Molecular Medicine, National Taiwan University College of Medicine, Taipei, Taiwan
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24
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Kilic M, Ozgül RK, Coşkun T, Yücel D, Karaca M, Sivri HS, Tokatli A, Sahin M, Karagöz T, Dursun A. Identification of mutations and evaluation of cardiomyopathy in Turkish patients with primary carnitine deficiency. JIMD Rep 2011; 3:17-23. [PMID: 23430869 DOI: 10.1007/8904_2011_36] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/12/2010] [Revised: 03/31/2011] [Accepted: 04/01/2011] [Indexed: 12/13/2022] Open
Abstract
Primary systemic carnitine deficiency (SCD) is an autosomal recessive disorder caused by defective cellular carnitine transport. Patients usually present with predominant metabolic or cardiac manifestations. SCD is caused by mutations in the organic cation/carnitine transporter OCTN2 (SLC22A5) gene. Mutation analysis of SLC22A5 gene was carried out in eight Turkish patients from six families. Six patients presented with signs and symptoms of heart failure, cardiomyopathy, and low plasma carnitine levels, five of them with concurrent anemia. A patient with dilated cardiomyopathy had also facial dysmorphia, microcephaly, and developmental delay. Tandem MS analyses in siblings of the patients revealed two more cases with low plasma carnitine levels. SCD diagnosis was confirmed in these two cases by mutation screening. These two cases were asymptomatic but echocardiography revealed left ventricular dilatation in one of them. Carnitine treatment was started before the systemic signs and symptoms developed in these patients. Mean value of serum carnitine levels of the patients was 2.63±1.92μmol/L at the time of diagnosis. After 1year of treatment, carnitine values increased to 16.62±5.11 (p<0.001) and all responded to carnitine supplementation clinically. Mutation screening of the OCTN2 gene study in the patients revealed two novel (p.G411V, p.G152R), and four previously identified mutations (p.R254X, p.R282X, p.R289X, p.T337Pfs12X). Early recognition and carnitine supplementation can be lifesaving in this inborn error of fatty acid oxidation.
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Affiliation(s)
- M Kilic
- Department of Pediatrics, Metabolism and Nutrition Unit, Hacettepe University, Ankara, Turkey,
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Katzberg H, Karamchandani J, So YT, Vogel H, Wang CH. End-stage cardiac disease as an initial presentation of systemic myopathies: case series and literature review. J Child Neurol 2010; 25:1382-8. [PMID: 20445193 DOI: 10.1177/0883073810367683] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
Life-threatening cardiomyopathy is associated with certain systemic myopathies and usually presents as an end-stage progression of the disease. However, cardiac symptoms can sometimes precede muscle weakness. The authors reviewed medical records from 2003 to 2008 on patients attending their neuromuscular clinic and identified patients who initially presented with an end-stage cardiomyopathy and were later diagnosed with a specific muscle disease through muscle biopsy. They report 5 cases of children who initially presented with cardiomyopathies without neuromuscular symptoms. The cardiac symptoms were so severe that 4 of them required cardiac transplantation and 1 died prior to transplantation. Review of muscle pathology confirmed the diagnoses of Becker muscular dystrophy, myofibrillar myopathy, mitochondrial myopathy with cytochrome oxidase deficiency, Danon disease, and glycogen storage disease. The authors conclude that cardiomyopathy can be the initial presentation of a wide spectrum of systemic myopathies. Careful evaluation of neuromuscular systems should be carried out in patients presenting with end-stage cardiomyopathies.
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Affiliation(s)
- Hans Katzberg
- Department of Neurology, Stanford University Medical Center, Stanford, California 94305-5235, USA
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26
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Niu DM, Chien YH, Chiang CC, Ho HC, Hwu WL, Kao SM, Chiang SH, Kao CH, Liu TT, Chiang H, Hsiao KJ. Nationwide survey of extended newborn screening by tandem mass spectrometry in Taiwan. J Inherit Metab Dis 2010; 33:S295-305. [PMID: 20567911 DOI: 10.1007/s10545-010-9129-z] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2010] [Revised: 05/07/2010] [Accepted: 05/10/2010] [Indexed: 11/26/2022]
Abstract
In Taiwan, during the period March 2000 to June 2009, 1,495,132 neonates were screened for phenylketonuria (PKU) and homocystinuria (HCU), and 1,321,123 neonates were screened for maple syrup urine disease (MSUD), methylmalonic academia (MMA), medium-chain acyl-coenzyme A (CoA) dehydrogenase (MCAD) deficiency, isovaleric academia (IVA), and glutaric aciduria type 1 (GA-1) using tandem mass spectrometry (MS/MS). In a pilot study, 592,717 neonates were screened for citrullinemia, 3-methylcrotonyl-CoA carboxylase deficiency (3-MCC) and other fatty acid oxidation defects in the MS/MS newborn screening. A total of 170 newborns and four mothers were confirmed to have inborn errors of metabolism. The overall incidence was approximately 1/5,882 (1/6,219 without mothers). The most common inborn errors were defects of phenylalanine metabolism [five classic PKU, 20 mild PKU, 40 mild hyperphenylalaninemia (HPA), and 13 6-pyruvoyl-tetrahydropterin synthase (PTPS) deficiency]. MSUD was the second most common amino acidopathy and, significantly, most MSUD patients (10/13) belonged to the Austronesian aboriginal tribes of southern Taiwan. The most frequently detected among organic acid disorders was 3-MCC deficiency (14 newborns and four mothers). GA-1 and MMA were the second most common organic acid disorders (13 and 13 newborns, respectively). In fatty acid disorders, five carnitine transport defect (CTD), five short-chain acyl-CoA dehydrogenase deficiency (SCAD), and two medium-chain acyl-CoA dehydrogenase (MCAD) deficiency were confirmed. This is the largest case of MS/MS newborn screening in an East-Asian population to date. We hereby report the incidences and outcomes of metabolic inborn error diseases found in our nationwide MS/MS newborn screening program.
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Affiliation(s)
- Dau-Ming Niu
- Institute of Clinical Medicine, School of Medicine, National Yang Ming University, No.155, Sec.2, Linong Street, Taipei, Taiwan.
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Lee NC, Tang NLS, Chien YH, Chen CA, Lin SJ, Chiu PC, Huang AC, Hwu WL. Diagnoses of newborns and mothers with carnitine uptake defects through newborn screening. Mol Genet Metab 2010; 100:46-50. [PMID: 20074989 DOI: 10.1016/j.ymgme.2009.12.015] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 12/23/2009] [Indexed: 11/24/2022]
Abstract
Carnitine uptake defect (CUD) is an autosomal recessive fatty acid oxidation defect caused by a deficiency of the high-affinity carnitine transporter OCTN2. CUD patients may present with hypoketotic hypoglycemia, hepatic encephalopathy or dilated cardiomyopathy. Tandem mass spectrometry screening of newborns can detect CUD, although transplacental transport of free carnitine from the mother may cause a higher free carnitine level and cause false negatives during newborn screening. From Jan 2001 to July 2009, newborns were screened for low free carnitine levels at the National Taiwan University Hospital screening center. Confirmation tests included dried blood spot free acylcarnitine levels and mutation analyses for both babies and their mothers. Sixteen newborns had confirmation tests for persistent low free carnitine levels; four had CUD, six had mothers with CUD, and six cases were false positives. All babies born to mothers with CUD had transient carnitine deficiency. The six mothers with CUD were put on carnitine supplementation (50-100mg/kg/day). One mother had dilated cardiomyopathy at diagnosis and her cardiac function improved after treatment. Analysis of the SLC22A5 gene revealed that p.S467C was the most common mutation in mothers with CUD, while p.R254X was the most common mutation in newborns and children with CUD. Newborn screening allows for the detection of CUD both in newborns and mothers, with an incidence in newborns of one in 67,000 (95% CI: one in 31,600-512,000) and a prevalence in mothers of one in 33,000 (95% CI: one in 18,700-169,000). Detection of CUD in mothers may prevent them from developing dilated cardiomyopathy.
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Affiliation(s)
- Ni-Chung Lee
- Department of Medical Genetics, National Taiwan University Hospital, Taipei, Taiwan
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28
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LinToh DS, Yee JY, Koo SH, Murray M, Lee EJD. Genetic Variations of the SLC22A5 Gene in the Chinese and Indian Populations of Singapore. Drug Metab Pharmacokinet 2010; 25:112-9. [DOI: 10.2133/dmpk.25.112] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Yamak AA, Bitar F, Karam P, Nemer G. Exclusive cardiac dysfunction in familial primary carnitine deficiency cases: a genotype-phenotype correlation. Clin Genet 2007; 72:59-62. [PMID: 17594400 DOI: 10.1111/j.1399-0004.2007.00814.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
MESH Headings
- Base Sequence
- Cardiomyopathy, Dilated/genetics
- Cardiomyopathy, Dilated/physiopathology
- Carnitine/deficiency
- Child
- Child, Preschool
- Codon, Nonsense
- DNA, Complementary/genetics
- Exons
- Female
- Genes, Recessive
- Genotype
- Humans
- Infant
- Lebanon
- Lipid Metabolism, Inborn Errors/genetics
- Lipid Metabolism, Inborn Errors/physiopathology
- Male
- Organic Cation Transport Proteins/genetics
- Pedigree
- Phenotype
- Solute Carrier Family 22 Member 5
- Ventricular Dysfunction, Left/genetics
- Ventricular Dysfunction, Left/physiopathology
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Schimmenti LA, Crombez EA, Schwahn BC, Heese BA, Wood TC, Schroer RJ, Bentler K, Cederbaum S, Sarafoglou K, McCann M, Rinaldo P, Matern D, di San Filippo CA, Pasquali M, Berry SA, Longo N. Expanded newborn screening identifies maternal primary carnitine deficiency. Mol Genet Metab 2007; 90:441-5. [PMID: 17126586 DOI: 10.1016/j.ymgme.2006.10.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2006] [Accepted: 10/17/2006] [Indexed: 12/30/2022]
Abstract
Primary carnitine deficiency impairs fatty acid oxidation and can result in hypoglycemia, hepatic encephalopathy, cardiomyopathy and sudden death. We diagnosed primary carnitine deficiency in six unrelated women whose unaffected infants were identified with low free carnitine levels (C0) by newborn screening using tandem mass spectrometry. Given the lifetime risk of morbidity or sudden death, identification of adult patients with primary carnitine deficiency is an added benefit of expanded newborn screening programs.
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Affiliation(s)
- Lisa A Schimmenti
- University of Minnesota, Department of Pediatrics, Division of Genetics and Metabolism, Institute of Human Genetics, Minneapolis, MN, USA
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Amat di San Filippo C, Pasquali M, Longo N. Pharmacological rescue of carnitine transport in primary carnitine deficiency. Hum Mutat 2006; 27:513-23. [PMID: 16652335 DOI: 10.1002/humu.20314] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Primary carnitine deficiency is a recessive disorder caused by heterogeneous mutations in the SLC22A5 gene encoding the OCTN2 carnitine transporter. Here we extend mutational analysis to eight new families with this disorder. To determine the mechanism by which missense mutations impaired carnitine transport, the OCTN2 transporter was tagged with the green fluorescent protein and expressed in CHO cells. Analysis by confocal microscopy indicated that several missense mutants (M1I, R169W, T232 M, G242 V, S280F, R282Q, W283R, A301D, W351R, R399Q, T440 M, E452 K, and T468R) matured normally to the plasma membrane. By contrast, other mutations (including R19P, DeltaF22, R83L, S280F, P398L, Y447C, and A142S/R488 H) caused significant retention of the mutant OCTN2 transporter in the cytoplasm. Failed maturation to the plasma membrane is a common mechanism in disorders affecting membrane transporters/ion channels, including cystic fibrosis. To correct this defect, we tested whether drugs reducing the efficiency of protein degradation in the endoplasmic reticulum (ER) (phenylbutyrate, curcumin) or capable of binding the OCTN2 carnitine transporter (verapamil, quinidine) could improve carnitine transport. Prolonged incubation with phenylbutyrate, quinidine, and verapamil partially stimulated carnitine transport, while curcumin was ineffective. These results indicate that OCTN2 mutations can affect carnitine transport by impairing maturation of transporters to the plasma membrane. Pharmacological therapy can be effective in partially restoring activity of mutant transporters.
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32
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Longo N, Amat di San Filippo C, Pasquali M. Disorders of carnitine transport and the carnitine cycle. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2006; 142C:77-85. [PMID: 16602102 PMCID: PMC2557099 DOI: 10.1002/ajmg.c.30087] [Citation(s) in RCA: 327] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Carnitine plays an essential role in the transfer of long-chain fatty acids across the inner mitochondrial membrane. This transfer requires enzymes and transporters that accumulate carnitine within the cell (OCTN2 carnitine transporter), conjugate it with long chain fatty acids (carnitine palmitoyl transferase 1, CPT1), transfer the acylcarnitine across the inner plasma membrane (carnitine-acylcarnitine translocase, CACT), and conjugate the fatty acid back to Coenzyme A for subsequent beta oxidation (carnitine palmitoyl transferase 2, CPT2). Deficiency of the OCTN2 carnitine transporter causes primary carnitine deficiency, characterized by increased losses of carnitine in the urine and decreased carnitine accumulation in tissues. Patients can present with hypoketotic hypoglycemia and hepatic encephalopathy, or with skeletal and cardiac myopathy. This disease responds to carnitine supplementation. Defects in the liver isoform of CPT1 present with recurrent attacks of fasting hypoketotic hypoglycemia. The heart and the muscle, which express a genetically distinct form of CPT1, are usually unaffected. These patients can have elevated levels of plasma carnitine. CACT deficiency presents in most cases in the neonatal period with hypoglycemia, hyperammonemia, and cardiomyopathy with arrhythmia leading to cardiac arrest. Plasma carnitine levels are extremely low. Deficiency of CPT2 present more frequently in adults with rhabdomyolysis triggered by prolonged exercise. More severe variants of CPT2 deficiency present in the neonatal period similarly to CACT deficiency associated or not with multiple congenital anomalies. Treatment for deficiency of CPT1, CPT2, and CACT consists in a low-fat diet supplemented with medium chain triglycerides that can be metabolized by mitochondria independently from carnitine, carnitine supplements, and avoidance of fasting and sustained exercise.
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Affiliation(s)
- Nicola Longo
- Division of Medical Genetics, Department of Pediatrics, University of Utah, 2C412 SOM, 50 North Medical Drive, Salt Lake City, UT, USA.
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Dobrowolski SF, McKinney JT, Amat di San Filippo C, Giak Sim K, Wilcken B, Longo N. Validation of dye-binding/high-resolution thermal denaturation for the identification of mutations in the SLC22A5 gene. Hum Mutat 2006; 25:306-13. [PMID: 15714519 DOI: 10.1002/humu.20137] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Primary carnitine deficiency is an autosomal recessive disorder of fatty acid oxidation resulting from defective carnitine transport. This disease is caused by mutations in the OCTN2 carnitine transporter encoded by the SLC22A5 gene. Here we validate dye-binding/high-resolution thermal denaturation as a screening procedure to identify novel mutations in this gene. This procedure is based on the amplification of DNA by PCR in capillaries with the dsDNA binding dye LCGreen I. The PCR reaction is then analyzed in the same capillary by high-resolution thermal denaturation. Samples with abnormal melting profiles are sequenced. This technique correctly identified all known patients who were compound heterozygotes for different mutations in the carnitine transporter gene and about 30% of homozygous patients. The remaining 70% of homozygous patients were identified by a second amplification, in which the patient's DNA was mixed with the DNA of a normal control. This screening system correctly identified eight novel mutations and both abnormal alleles in six new families with primary carnitine deficiency. The causative role of the missense mutations identified (c.3G>T/p.M1I, c.695C>T/p.T232M, and c.1403 C>G/p.T468R) was confirmed by expression in Chinese hamster ovary (CHO) cells. These results expand the mutational spectrum in primary carnitine deficiency and indicate dye-binding/high-resolution thermal denaturation as an ideal system to screen for mutations in diseases with no prevalent molecular alteration.
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Melegh B, Bene J, Mogyorósy G, Havasi V, Komlósi K, Pajor L, Oláh E, Kispál G, Sumegi B, Méhes K. Phenotypic manifestations of the OCTN2 V295X mutation: Sudden infant death and carnitine-responsive cardiomyopathy in Roma families. ACTA ACUST UNITED AC 2004; 131:121-6. [PMID: 15487009 DOI: 10.1002/ajmg.a.30207] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In two non-consanguineous Hungarian Roma (Gypsy) children who presented with cardiomyopathy and decreased plasma carnitine levels, we identified homozygous deletion of 17081C of the SLC22A5 gene that results in a frameshift at R282D and leads ultimately to a premature stop codon (V295X) in the OCTN2 carnitine transporter. Carnitine treatment resulted in dramatic improvement of the cardiac symptoms, echocardiographic, and EKG findings in both cases. Family investigations revealed four sudden deaths, two of them corresponded to the classic SIDS phenotype. In postmortem tissue specimens available from three of them we could verify the homozygous mutation. In liver tissue reserved from two patients lipid droplet vacuolization could be observed; the lipid vacuoles were located mainly in the peripherolobular regions of the acini. In the heart tissue signs of generalized hypertrophy and lipid vacuoles were seen predominantly in the subendocardial areas in both cases; some aggregates of smaller lipid vacuoles were separated, apparently by membranes. Review of all OCTN2 deficiency cases reported so far revealed that this is the first presentation of histopathology in classic familial sudden infant death syndrome (SIDS) with an established SLC22A5 mutation. In addition to the two affected homozygous cardiomyopathic children and three homozygous sudden death patients, the genetic analysis in 25 relatives showed 14 carriers. The mutant gene derived from five non-consanguineous grandparents, each of them having 6-14 brothers and sisters. This alone suggests a wide ancestral spread of the mutation in certain Roma subpopulations.
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Affiliation(s)
- Béla Melegh
- Department of Medical Genetics and Child Development, University of Pécs, Pécs, Hungary
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Abstract
Carrier-mediated processes, often referred to as transporters, play key roles in the reabsorption and secretion of many endogenous and xenobiotic compounds by the kidney. The renal proximal tubule is the primary site of active transport for a wide variety of substrates, including organic anions/cations, peptides, and nucleosides. During the past decade, significant advances in molecular identification and characterization of transporter proteins have been made. Although it is generally noted that these transporters significantly contribute to renal drug handling and variability in drug disposition, the extent of our knowledge regarding the specific roles of such transporters in drug disposition and drug-drug interactions remains, for the most part, limited. In this review, we summarize recent progress in terms of molecular and functional characterization of renal transporters and their clinical relevance to drug therapy.
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Affiliation(s)
- Wooin Lee
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-6602, USA
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Lamhonwah AM, Onizuka R, Olpin SE, Muntoni F, Tein I. OCTN2 mutation (R254X) found in Saudi Arabian kindred: recurrent mutation or ancient founder mutation? J Inherit Metab Dis 2004; 27:473-6. [PMID: 15303004 DOI: 10.1023/b:boli.0000037339.25821.87] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The truncating R254X mutation in the OCTN2 gene results in defective high-affinity carnitine transport and has been previously described as a founder mutation in the Chinese population. We now report a Saudi Arabian kindred with this same mutation, suggesting that it may be a recurrent mutation or a very ancient founder mutation. Western blot analysis of skin fibroblast lysates from the proband with our specific anti-murine OCTN2 antibody revealed the absence of the OCTN2 protein.
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Affiliation(s)
- A-M Lamhonwah
- Department of Pediatrics, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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