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Lin Y, Lin C, Zheng Z, Huang C, Peng W. Newborn screening for primary carnitine deficiency using a second-tier genetic test. J Pediatr Endocrinol Metab 2024; 37:163-169. [PMID: 38158618 DOI: 10.1515/jpem-2023-0513] [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: 11/16/2023] [Accepted: 12/18/2023] [Indexed: 01/03/2024]
Abstract
OBJECTIVES Newborn screening (NBS) for primary carnitine deficiency (PCD) exhibits suboptimal performance. This study proposes a strategy to enhance the efficacy of second-tier genetic screening by adjusting the cutoff value for free carnitine (C0). METHODS Between January 2021 and December 2022, we screened 119,898 neonates for inborn metabolic disorders. Neonates with C0 levels below 12 μmol/L were randomly selected for second-tier genetic screening, employing a novel matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) assay. RESULTS In total, 2,515 neonates with C0 <12 μmol/L underwent further screening, including 206 neonates with C0 <8.5 μmol/L and 320 neonates with 8.5G, accounting for 25 % (7/28) of allelic frequencies. CONCLUSIONS A novel MALDI-TOF MS assay targeting 21 SLC22A5 variants in a Chinese population was successfully established. This assay exhibits a high detection and diagnostic rate, making it suitable for population-based genetic screening. Combined genetic screening is recommended to enhance the efficiency of PCD-NBS.
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Affiliation(s)
- Yiming Lin
- Department of Clinical Laboratory, Quanzhou Maternity and Children's Hospital, Quanzhou, Fujian Province, P.R. China
| | - Chunmei Lin
- Department of Clinical Laboratory, Quanzhou Maternity and Children's Hospital, Quanzhou, Fujian Province, P.R. China
| | - Zhenzhu Zheng
- Department of Clinical Laboratory, Quanzhou Maternity and Children's Hospital, Quanzhou, Fujian Province, P.R. China
| | - Chenggang Huang
- Zhejiang Biosan Biochemical Technologies Co., Ltd., Hangzhou, Zhejiang Province, P.R. China
| | - Weilin Peng
- Department of Clinical Laboratory, Quanzhou Maternity and Children's Hospital, Quanzhou, Fujian Province, P.R. China
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2
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Lin Y, Lin C, Lin B, Zheng Z, Lin W, Chen Y, Chen D, Peng W. Newborn screening for fatty acid oxidation disorders in a southern Chinese population. Heliyon 2024; 10:e23671. [PMID: 38187300 PMCID: PMC10770602 DOI: 10.1016/j.heliyon.2023.e23671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 11/23/2023] [Accepted: 12/09/2023] [Indexed: 01/09/2024] Open
Abstract
Background and aims Fatty acid oxidation disorders (FAODs) are a group of autosomal recessive metabolic diseases included in many newborn screening (NBS) programs, but the incidence and disease spectrum vary widely between ethnic groups. We aimed to elucidate the incidence, disease spectrum, and genetic features of FAODs in a southern Chinese population. Materials and methods The FAODs screening results of 643,606 newborns from 2014 to 2022 were analyzed. Results Ninety-two patients were eventually diagnosed with FAODs, of which 61 were PCD, 20 were MADD, 5 were SCADD, 4 were VLCADD, and 2 were CPT-IAD. The overall incidence of FAODs was 1:6996 (95 % CI: 1:5814-1:8772) newborns. All PCD patients had low C0 levels during NBS, while nine patients (14.8 %) had normal C0 levels during the recall review. All but one MADD patients had elevated C8, C10, and C12 levels during NBS, while eight patients (40 %) had normal acylcarnitine levels during the recall review. The most frequent SLC22A5 variant was c.760C > T (p.R254*) with an allele frequency of 29.51 %, followed by c.51C > G (p.F17L) (17.21 %) and c.1400C > G (p.S467C) (16.39 %). The most frequent ETFDH variant was c.250G > A (p.A84T) with an allelic frequency of 47.5 %, followed by c.524G > A (R175H) (12.5 %), c.998A > G (p.Y333C) (12.5 %), and c.1657T > C (p.Y553H) (7.5 %). Conclusion The prevalence, disease spectrum, and genetic characteristics of FAODs in a southern Chinese population were clarified. PCD was the most common FAOD, followed by MADD. Hotspot variants were found in SLC22A5 and ETFDH genes, while the remaining FAODs showed great molecular heterogeneity. Incorporating second-tier genetic screening is critical for FAODs.
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Affiliation(s)
- Yiming Lin
- Department of Clinical Laboratory, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province, 362000, China
| | - Chunmei Lin
- Department of Clinical Laboratory, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province, 362000, China
| | - Bangbang Lin
- Administrative office, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province, 362000, China
| | - Zhenzhu Zheng
- Department of Clinical Laboratory, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province, 362000, China
| | - Weihua Lin
- Center of Neonatal Disease Screening, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province, 362000, China
| | - Yanru Chen
- Center of Neonatal Disease Screening, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province, 362000, China
| | - Dongmei Chen
- Department of Neonatology, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province, 362000, China
| | - Weilin Peng
- Department of Clinical Laboratory, Quanzhou Maternity and Children's Hospital, 700 Fengze Street, Quanzhou, Fujian Province, 362000, China
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Cao Z, He X, Wang D, Gu M, Suo F, Qiang R, Zhang R, Song C, Wang X, Zhu B, Cao D, Yu H, Qu Y, Shen G, Wu J, Wang P, Wang J, Zhang H, Yan Z, Yu G, Zou L. Targeted exome sequencing strategy (NeoEXOME) for Chinese newborns using a pilot study with 3423 neonates. Mol Genet Genomic Med 2024; 12:e2357. [PMID: 38284445 PMCID: PMC10795095 DOI: 10.1002/mgg3.2357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 09/15/2023] [Accepted: 12/26/2023] [Indexed: 01/30/2024] Open
Abstract
BACKGROUND Newborn screening (NBS) aims to detect congenital anomalies, and next-generation sequencing (NGS) has shown promise in this aspect. However, the NBS strategy for monogenic inherited diseases in China remains insufficient. METHODS We developed a NeoEXOME panel comprising 601 genes that are relevant to the Chinese population found through extensive research on available databases. An interpretation system to grade the results into positive (high-risk, moderate-risk, and low-risk genotypes), negative, and carrier according to the American College of Medical Genetics (ACMG) guidelines was also developed. We validated the panel to evaluate its efficacy by using data from the "1000 Genomes Project" and conducted a pilot multicenter study involving 3423 neonates. RESULTS The NGS positive rate in the 1000 Genomes Project was 7.6% (23/301), whereas the rate was 12.0% in the multicenter study, including 3249 recruited neonates. Notably, in 200 neonates, positive per conventional NBS, 58.5% (69/118) showed results consistent with NGS. In the remaining 3049 neonates showing negative results in conventional NBS, 271 (8.9%) were positive per NGS, and nine of them were clinically diagnosed with diseases in the follow-up. CONCLUSION We successfully designed a NeoEXOME panel for targeted sequencing of monogenic inherited diseases in NBS. The panel demonstrated high performance in the Chinese population, particularly for the early detection of diseases with no biochemical markers.
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Affiliation(s)
- Ziyang Cao
- Clinical Research Unit, Shanghai Children's HospitalShanghai Jiao Tong University Medical SchoolShanghaiChina
- Institute of Pediatric Infection, Immunity, and Critical Care MedicineShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Xiaoyan He
- Center for Clinical Molecular Laboratory Medicine of Children's Hospital of Chongqing Medical UniversityChongqingChina
| | - Dongjuan Wang
- Center for Clinical Molecular Laboratory Medicine of Children's Hospital of Chongqing Medical UniversityChongqingChina
| | - Maosheng Gu
- Center of Medical GeneticsXuzhou Maternal and Child Health Care HospitalXuzhouChina
| | - Feng Suo
- Center of Medical GeneticsXuzhou Maternal and Child Health Care HospitalXuzhouChina
| | - Rong Qiang
- Center of Medical GeneticsNorthwest Women and Children's HospitalXi'anChina
| | - Ruixue Zhang
- Center of Medical GeneticsNorthwest Women and Children's HospitalXi'anChina
| | - Chengrong Song
- Center of Medical GeneticsNorthwest Women and Children's HospitalXi'anChina
| | - Xiaohua Wang
- Center of Medical GeneticsInner Mongolia Maternal and Child Health Care HospitalHohhotChina
| | - Bo Zhu
- Center of Medical GeneticsInner Mongolia Maternal and Child Health Care HospitalHohhotChina
| | - Donghua Cao
- Medical Genetic LaboratoryDalian Municipal Women and Children's Medical Center (Group)DalianChina
- Genetic LaboratoryShenyang Jinghua Hospital Co., LtdShenyangChina
| | - Haihua Yu
- Medical Genetic LaboratoryDalian Municipal Women and Children's Medical Center (Group)DalianChina
| | - Yiping Qu
- Newborn Screening Center of Children's Hospital of Zhejiang University School of MedicineHangzhouChina
| | - Guosong Shen
- Medical Laboratory Center of Huzhou Maternal and Child Health Care HospitalHuzhouChina
| | - Jian Wu
- Research and Development DepartmentMyGenostics Inc.BeijingChina
| | - Pengpeng Wang
- Research and Development DepartmentMyGenostics Inc.BeijingChina
| | - Jinxia Wang
- Clinical Research Unit, Shanghai Children's HospitalShanghai Jiao Tong University Medical SchoolShanghaiChina
- Institute of Pediatric Infection, Immunity, and Critical Care MedicineShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Hongyang Zhang
- Clinical Research Unit, Shanghai Children's HospitalShanghai Jiao Tong University Medical SchoolShanghaiChina
- Institute of Pediatric Infection, Immunity, and Critical Care MedicineShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Zijun Yan
- Clinical Research Unit, Shanghai Children's HospitalShanghai Jiao Tong University Medical SchoolShanghaiChina
- Institute of Pediatric Infection, Immunity, and Critical Care MedicineShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Guangjun Yu
- Clinical Research Unit, Shanghai Children's HospitalShanghai Jiao Tong University Medical SchoolShanghaiChina
- Institute of Pediatric Infection, Immunity, and Critical Care MedicineShanghai Jiao Tong University School of MedicineShanghaiChina
| | - Lin Zou
- Clinical Research Unit, Shanghai Children's HospitalShanghai Jiao Tong University Medical SchoolShanghaiChina
- Institute of Pediatric Infection, Immunity, and Critical Care MedicineShanghai Jiao Tong University School of MedicineShanghaiChina
- Center for Clinical Molecular Laboratory Medicine of Children's Hospital of Chongqing Medical UniversityChongqingChina
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4
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Liu G, Liu X, Lin Y. Newborn screening for inborn errors of metabolism in a northern Chinese population. J Pediatr Endocrinol Metab 2023; 36:278-282. [PMID: 36662638 DOI: 10.1515/jpem-2022-0543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 01/02/2023] [Indexed: 01/21/2023]
Abstract
OBJECTIVES Newborn screening (NBS) for inborn errors of metabolism (IEMs) has been successfully implemented in China. However, the data on the IEM profiles in many regions are lacking. This study aimed to report the incidence, disease spectrum, and genetic profile of IEMs in northern China. METHODS A total of 36,590 newborns were screened using tandem mass spectrometry between January 2016 and April 2022. Newborns with positive results were referred for confirmatory testing. RESULTS Ten patients were confirmed to have IEMs, with an overall incidence of 1:3,539 in the Rizhao region. Five types of IEMs were detected, including four patients with propionic acidemia (PA), three patients with methylmalonic acidemia (MMA), one of each with citrin deficiency, primary carnitine deficiency, and isobutyryl-CoA dehydrogenase deficiency. PA was the most common IEM, with an unexpectedly high incidence of 1:8,848, followed by MMA, with an incidence rate of 1:11,797. All patients had abnormal screening markers and harbored biallelic variants in their respective causative genes. Two novel PCCB variants (c.505G>A and c.1123_1124insG) were identified in patients with PA. In silico analyses predicted that these two variants were potentially pathogenic. CONCLUSIONS This study preliminarily clarified the incidence, disease spectrum, and genetic profile of IEMs in the Rizhao region. PA is the most common IEM and MMA is the second most common in our region. The two novel identified PCCB variants further expand the variant spectrum of PA. More attention should be paid to NBS, early diagnosis, and management of PA and MA.
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Affiliation(s)
- Genxian Liu
- Center of Medical Genetics, Rizhao Maternal and Child Health Care Hospital, Shandong Province, P.R. China
| | - Xingying Liu
- Clinical Laboratory, Rizhao Central Hospital Rizhao, Shandong Province, P.R. China
| | - Yiming Lin
- Center of Neonatal Disease Screening, Quanzhou Maternity and Children's Hospital, Quanzhou, Fujian Province, P.R. China
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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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Liammongkolkul S, Boonyawat B, Vijarnsorn C, Tim-Aroon T, Wasant P, Vatanavicharn N. Phenotypic and molecular features of Thai patients with primary carnitine deficiency. Pediatr Int 2023; 65:e15404. [PMID: 36321377 DOI: 10.1111/ped.15404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 09/13/2022] [Accepted: 09/22/2022] [Indexed: 11/07/2022]
Abstract
BACKGROUND Primary carnitine deficiency (PCD) is screened by expanded newborn screening (NBS) using tandem mass spectrometry (MS/MS) that can detect both affected neonates and mothers. This study aimed to delineate the clinical, biochemical, and molecular findings of Thai PCD patients. METHODS Expanded NBS using MS/MS was implemented in Bangkok and 146,757 neonates were screened between 2014 and 2018. PCD was screened by low free carnitine (C0) levels in dried blood spots. Plasma C0 levels and C0 clearance values were measured in neonates and their mothers with positive screening results. Clinically diagnosed cases were described. The coding regions and intron-exon boundaries of the SLC22A5 gene were sequenced in all cases with low plasma C0 levels. RESULTS There were 14 cases with confirmed PCD: two clinically diagnosed cases, and 12 cases identified through NBS including five newborns, six mothers, and one older sibling. Thus, the incidence of PCD in neonates was 1:29,351. All affected neonates and mothers were asymptomatic except one mother with dilated cardiomyopathy. SLC22A5 gene sequencing identified biallelic causative variants in all cases, comprising 10 different variants of which four were novel. c.51C > G (p.Phe17Leu) and c.760C > T (p.Arg254Ter) were the most prevalent variants in this study. Cases with significant clinical features tended to have higher C0 clearance values. CONCLUSIONS Primary carnitine deficiency is a common inherited metabolic disorder (IMD) in Thailand. Our findings broaden the spectrum of SLC22A5 variants. The future national NBS program will shed more light on PCD and other IMDs in Thailand.
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Affiliation(s)
- Somporn Liammongkolkul
- Division of Medical Genetics, Department of Pediatrics, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Boonchai Boonyawat
- Division of Medical Genetics, Department of Pediatrics, Phramongkutklao Hospital and College of Medicine, Bangkok, Thailand
| | - Chodchanok Vijarnsorn
- Division of Cardiology, Department of Pediatrics, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Thipwimol Tim-Aroon
- Division of Medical Genetics, Department of Pediatrics, Faculty of Medicine Ramathbodi Hospital, Mahidol University, Bangkok, Thailand
| | - Pornswan Wasant
- Division of Medical Genetics, Department of Pediatrics, Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Nithiwat Vatanavicharn
- Division of Medical Genetics, Department of Pediatrics, Siriraj Hospital, Mahidol University, Bangkok, Thailand
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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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Incorporating second-tier genetic screening for multiple acyl-CoA dehydrogenase deficiency. Clin Chim Acta 2022; 537:181-187. [DOI: 10.1016/j.cca.2022.10.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 10/28/2022] [Indexed: 11/07/2022]
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Koleske ML, McInnes G, Brown JEH, Thomas N, Hutchinson K, Chin MY, Koehl A, Arkin MR, Schlessinger A, Gallagher RC, Song YS, Altman RB, Giacomini KM. Functional genomics of OCTN2 variants informs protein-specific variant effect predictor for Carnitine Transporter Deficiency. Proc Natl Acad Sci U S A 2022; 119:e2210247119. [PMID: 36343260 PMCID: PMC9674959 DOI: 10.1073/pnas.2210247119] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 09/16/2022] [Indexed: 11/09/2022] Open
Abstract
Genetic variants in SLC22A5, encoding the membrane carnitine transporter OCTN2, cause the rare metabolic disorder Carnitine Transporter Deficiency (CTD). CTD is potentially lethal but actionable if detected early, with confirmatory diagnosis involving sequencing of SLC22A5. Interpretation of missense variants of uncertain significance (VUSs) is a major challenge. In this study, we sought to characterize the largest set to date (n = 150) of OCTN2 variants identified in diverse ancestral populations, with the goals of furthering our understanding of the mechanisms leading to OCTN2 loss-of-function (LOF) and creating a protein-specific variant effect prediction model for OCTN2 function. Uptake assays with 14C-carnitine revealed that 105 variants (70%) significantly reduced transport of carnitine compared to wild-type OCTN2, and 37 variants (25%) severely reduced function to less than 20%. All ancestral populations harbored LOF variants; 62% of green fluorescent protein (GFP)-tagged variants impaired OCTN2 localization to the plasma membrane of human embryonic kidney (HEK293T) cells, and subcellular localization significantly associated with function, revealing a major LOF mechanism of interest for CTD. With these data, we trained a model to classify variants as functional (>20% function) or LOF (<20% function). Our model outperformed existing state-of-the-art methods as evaluated by multiple performance metrics, with mean area under the receiver operating characteristic curve (AUROC) of 0.895 ± 0.025. In summary, in this study we generated a rich dataset of OCTN2 variant function and localization, revealed important disease-causing mechanisms, and improved upon machine learning-based prediction of OCTN2 variant function to aid in variant interpretation in the diagnosis and treatment of CTD.
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Affiliation(s)
- Megan L. Koleske
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94143
| | - Gregory McInnes
- Biomedical Informatics Training Program, Stanford University, Stanford, CA 94305
- Empirico Inc., San Diego, CA 92122
| | - Julia E. H. Brown
- Program in Bioethics, University of California, San Francisco, CA 94143
- Institute for Health & Aging, University of California, San Francisco, CA 94143
| | - Neil Thomas
- Computer Science Division, University of California, Berkeley, CA 94720
| | - Keino Hutchinson
- Department of Pharmacological Sciences, Icahn School of Medicine at Mt. Sinai, New York, NY 10029
| | - Marcus Y. Chin
- Small Molecule Discovery Center, Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143
| | - Antoine Koehl
- Department of Statistics, University of California, Berkeley, CA 94720
| | - Michelle R. Arkin
- Small Molecule Discovery Center, Department of Pharmaceutical Chemistry, University of California, San Francisco, CA 94143
| | - Avner Schlessinger
- Department of Pharmacological Sciences, Icahn School of Medicine at Mt. Sinai, New York, NY 10029
| | - Renata C. Gallagher
- Institute for Human Genetics, University of California, San Francisco, CA 94143
- Department of Pediatrics, University of California, San Francisco, CA 94143
| | - Yun S. Song
- Computer Science Division, University of California, Berkeley, CA 94720
- Department of Statistics, University of California, Berkeley, CA 94720
| | - Russ B. Altman
- Department of Bioengineering, Stanford University, Stanford, CA 94305
- Department of Genetics, Stanford University, Stanford, CA 94305
| | - Kathleen M. Giacomini
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, CA 94143
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10
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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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