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Jia N, Yu S, Zhang G, Li L, Wang J, Lai C. Recurrent MECR R258W causes adult-onset optic atrophy: A case report. Eur J Med Genet 2024; 68:104917. [PMID: 38296034 DOI: 10.1016/j.ejmg.2024.104917] [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: 06/19/2023] [Revised: 01/13/2024] [Accepted: 01/28/2024] [Indexed: 02/07/2024]
Abstract
MECR-related neurologic disorder, also known as mitochondrial enoyl CoA reductase protein-associated neurodegeneration (MEPAN) or dystonia with optic atrophy and basal ganglia abnormalities in childhood (MIM: #617282), is an autosomal recessive inherited disease characterized by a progressive childhood-onset movement disorder and optic atrophy. Here we report a 19-year-old male, presented with progressive visual failure, nystagmus, and right orbital pain, with no history of movement or eye disorder in his childhood. His visual decline started at age 18 years, whereas nystagmus emerged seven months later. Analysis of whole-exome sequencing (WES) revealed a homozygous recurrent variant (NM_016011.5:c.772C > T, p.Arg258Trp) in MECR. These findings suggest phenotypic heterogeneity in MECR-related neurologic disorder, thus, more relevant case screening, will help to delineate the genotype-phenotype correlation of the MECR gene.
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Affiliation(s)
- Nan Jia
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Shuiqing Yu
- Beijing Chigene Translational Medical Research Center Co. Ltd., Beijing, China
| | - Geng Zhang
- Beijing Chigene Translational Medical Research Center Co. Ltd., Beijing, China
| | - Lin Li
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Jiawei Wang
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Chuntao Lai
- Department of Neurology, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
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2
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Wedan RJ, Longenecker JZ, Nowinski SM. Mitochondrial fatty acid synthesis is an emergent central regulator of mammalian oxidative metabolism. Cell Metab 2024; 36:36-47. [PMID: 38128528 PMCID: PMC10843818 DOI: 10.1016/j.cmet.2023.11.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 11/27/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023]
Abstract
Contrary to their well-known functions in nutrient breakdown, mitochondria are also important biosynthetic hubs and express an evolutionarily conserved mitochondrial fatty acid synthesis (mtFAS) pathway. mtFAS builds lipoic acid and longer saturated fatty acids, but its exact products, their ultimate destination in cells, and the cellular significance of the pathway are all active research questions. Moreover, why mitochondria need mtFAS despite their well-defined ability to import fatty acids is still unclear. The identification of patients with inborn errors of metabolism in mtFAS genes has sparked fresh research interest in the pathway. New mammalian models have provided insights into how mtFAS coordinates many aspects of oxidative mitochondrial metabolism and raise questions about its role in diseases such as obesity, diabetes, and heart failure. In this review, we discuss the products of mtFAS, their function, and the consequences of mtFAS impairment across models and in metabolic disease.
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Affiliation(s)
- Riley J Wedan
- Department of Metabolism and Nutritional Programming, The Van Andel Institute, Grand Rapids, MI 49503, USA; College of Human Medicine, Michigan State University, Grand Rapids, MI 49503, USA
| | - Jacob Z Longenecker
- Department of Metabolism and Nutritional Programming, The Van Andel Institute, Grand Rapids, MI 49503, USA
| | - Sara M Nowinski
- Department of Metabolism and Nutritional Programming, The Van Andel Institute, Grand Rapids, MI 49503, USA.
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3
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Rawson F, Christen M, Rose J, Paran E, Leeb T, Fadda A. Polioencephalopathy in Eurasier dogs. J Vet Intern Med 2024; 38:277-284. [PMID: 38041431 PMCID: PMC10800227 DOI: 10.1111/jvim.16945] [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: 09/18/2023] [Accepted: 11/14/2023] [Indexed: 12/03/2023] Open
Abstract
BACKGROUND Polioencephalopathies secondary to inborn errors of metabolism have been described in dogs, but few genetically characterized. OBJECTIVES Clinically and genetically characterize polioencephalopathy in a family of Eurasier dogs. ANIMALS Three Eurasier dogs (littermates) presented with early onset movement disorders (9 weeks in 2, 4-6 months in 1). Progressive gait abnormalities were detected in 2 of the dogs, persistent divergent strabismus in 1, whereas consciousness and behavior remained intact in all dogs. One dog was euthanized at 25 months. METHODS Video footage was assessed in all dogs, and Dogs 1 and 2 had examinations and investigations performed. Whole genome sequencing of Dog 1 and further genetic analyses in the family were performed. A cohort of 115 Eurasier controls was genotyped for specific variants. RESULTS Episodes were characterized by generalized ataxia, as well as a hypermetric thoracic limb gait, dystonia, and irregular flexion and extension movements of the thoracic limbs. Magnetic resonance imaging of the brain in Dogs 1 and 2 identified symmetrical, bilateral T2 and fluid attenuated inversion recovery hyperintense, T1 hypo to isointense, nonenhancing lesions of the caudate nucleus, lateral and medial geniculate nuclei, thalamus, hippocampus, rostral colliculus and mild generalized brain atrophy. Genetic analyses identified a homozygous mitochondrial trans-2-enoyl-CoA reductase (MECR) missense variant in all 3 dogs, and a homozygous autophagy-related gene 4D (ATG4D) missense variant in Dogs 1 and 2. CONCLUSIONS AND CLINICAL IMPORTANCE We describe a presumed hereditary and progressive polioencephalopathy in a family of Eurasier dogs. Further research is needed to establish the role of the MECR gene in dogs and the pathogenic effects of the detected variants.
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Affiliation(s)
- Faye Rawson
- Langford Veterinary ServicesUniversity of BristolBristolUK
| | - Matthias Christen
- Institute of Genetics, Vetsuisse FacultyUniversity of BernBernSwitzerland
| | | | - Emilie Paran
- Langford Veterinary ServicesUniversity of BristolBristolUK
| | - Tosso Leeb
- Institute of Genetics, Vetsuisse FacultyUniversity of BernBernSwitzerland
| | - Angela Fadda
- Langford Veterinary ServicesUniversity of BristolBristolUK
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4
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Fiorini C, Degiorgi A, Cascavilla ML, Tropeano CV, La Morgia C, Battista M, Ormanbekova D, Palombo F, Carbonelli M, Bandello F, Carelli V, Maresca A, Barboni P, Baruffini E, Caporali L. Recessive MECR pathogenic variants cause an LHON-like optic neuropathy. J Med Genet 2023; 61:93-101. [PMID: 37734847 PMCID: PMC10804020 DOI: 10.1136/jmg-2023-109340] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 08/11/2023] [Indexed: 09/23/2023]
Abstract
BACKGROUND Leber's hereditary optic neuropathy (LHON) is a mitochondrial disorder characterised by complex I defect leading to sudden degeneration of retinal ganglion cells. Although typically associated with pathogenic variants in mitochondrial DNA, LHON was recently described in patients carrying biallelic variants in nuclear genes DNAJC30, NDUFS2 and MCAT. MCAT is part of mitochondrial fatty acid synthesis (mtFAS), as also MECR, the mitochondrial trans-2-enoyl-CoA reductase. MECR mutations lead to a recessive childhood-onset syndromic disorder with dystonia, optic atrophy and basal ganglia abnormalities. METHODS We studied through whole exome sequencing two sisters affected by sudden and painless visual loss at young age, with partial recovery and persistent central scotoma. We modelled the candidate variant in yeast and studied mitochondrial dysfunction in yeast and fibroblasts. We tested protein lipoylation and cell response to oxidative stress in yeast. RESULTS Both sisters carried a homozygous pathogenic variant in MECR (p.Arg258Trp). In yeast, the MECR-R258W mutant showed an impaired oxidative growth, 30% reduction in oxygen consumption rate and 80% decrease in protein levels, pointing to structure destabilisation. Fibroblasts confirmed the reduced amount of MECR protein, but failed to reproduce the OXPHOS defect. Respiratory complexes assembly was normal. Finally, the yeast mutant lacked lipoylation of key metabolic enzymes and was more sensitive to H2O2 treatment. Lipoic Acid supplementation partially rescued the growth defect. CONCLUSION We report the first family with homozygous MECR variant causing an LHON-like optic neuropathy, which pairs the recent MCAT findings, reinforcing the impairment of mtFAS as novel pathogenic mechanism in LHON.
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Affiliation(s)
- Claudio Fiorini
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Andrea Degiorgi
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Maria Lucia Cascavilla
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milano, Italy
| | | | - Chiara La Morgia
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Marco Battista
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Danara Ormanbekova
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Flavia Palombo
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Michele Carbonelli
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Francesco Bandello
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Valerio Carelli
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
| | - Alessandra Maresca
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
| | - Piero Barboni
- Department of Ophthalmology, University Vita-Salute, IRCCS Ospedale San Raffaele, Milano, Italy
| | - Enrico Baruffini
- Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Parma, Italy
| | - Leonardo Caporali
- Programma di Neurogenetica, IRCCS Istituto Delle Scienze Neurologiche di Bologna, Bologna, Italy
- Department of Biomedical and NeuroMotor Sciences (DIBINEM), University of Bologna, Bologna, Italy
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5
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Gupta PR, Gospe SM. Ophthalmic manifestations of MEPAN syndrome. Ophthalmic Genet 2023; 44:469-474. [PMID: 36262091 DOI: 10.1080/13816810.2022.2135112] [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: 07/01/2022] [Revised: 09/20/2022] [Accepted: 10/03/2022] [Indexed: 10/24/2022]
Abstract
BACKGROUND Mitochondrial enoyl CoA reductase protein-associated neurodegeneration (MEPAN) syndrome is an ultra-rare autosomal recessive disorder caused by loss-of-function mutations in the MECR gene. The syndrome is characterized by dystonia in early childhood, basal ganglia signal abnormalities on MRI, and subsequent optic atrophy, with relative sparing of cognition. We characterize the ophthalmic manifestations observed in a patient with MEPAN syndrome, as a detailed account of ocular findings has not been published to date. METHODS Case study of a patient with genetically confirmed MEPAN syndrome, with full ophthalmic evaluation including slit-lamp exam, sensorimotor exam, fundus photography, retinal ocular coherence tomography (OCT), electroretinography, visual evoked potentials, and visual field testing. RESULTS The patient exhibited decreased visual acuity of 20/150 in both eyes with moderate dyschromatopsia on pseudoisochromatic plate testing, while peripheral vision was largely intact on Goldmann visual field testing. Fundus exam revealed bilateral optic atrophy with pallor most pronounced temporally, corresponding to OCT findings of diffuse retinal nerve fiber layer thinning most prominent in the papillomacular bundle region and severe ganglion cell layer thinning in the maculae. She also displayed a high frequency horizontal end-gaze nystagmus and symmetric bilateral external ophthalmoplegia. CONCLUSIONS The pattern of bilateral optic atrophy in our patient with MEPAN syndrome shows predilection for the papillomacular bundle, similar to that seen in other mitochondrial disorders with optic neuropathy, such as Leber Hereditary Optic Neuropathy and Dominant Optic Atrophy. Our patient's external ophthalmoplegia is another neuro-ophthalmic finding that may be seen in patients with heritable mitochondrial disease, either as an isolated ocular phenotype or within a constellation of systemic manifestations.
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Affiliation(s)
| | - Sidney M Gospe
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA
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6
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Dutta D, Kanca O, Byeon SK, Marcogliese PC, Zuo Z, Shridharan RV, Park JH, Lin G, Ge M, Heimer G, Kohler JN, Wheeler MT, Kaipparettu BA, Pandey A, Bellen HJ. A defect in mitochondrial fatty acid synthesis impairs iron metabolism and causes elevated ceramide levels. Nat Metab 2023; 5:1595-1614. [PMID: 37653044 DOI: 10.1038/s42255-023-00873-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2022] [Accepted: 07/21/2023] [Indexed: 09/02/2023]
Abstract
In most eukaryotic cells, fatty acid synthesis (FAS) occurs in the cytoplasm and in mitochondria. However, the relative contribution of mitochondrial FAS (mtFAS) to the cellular lipidome is not well defined. Here we show that loss of function of Drosophila mitochondrial enoyl coenzyme A reductase (Mecr), which is the enzyme required for the last step of mtFAS, causes lethality, while neuronal loss of Mecr leads to progressive neurodegeneration. We observe a defect in Fe-S cluster biogenesis and increased iron levels in flies lacking mecr, leading to elevated ceramide levels. Reducing the levels of either iron or ceramide suppresses the neurodegenerative phenotypes, indicating an interplay between ceramide and iron metabolism. Mutations in human MECR cause pediatric-onset neurodegeneration, and we show that human-derived fibroblasts display similar elevated ceramide levels and impaired iron homeostasis. In summary, this study identifies a role of mecr/MECR in ceramide and iron metabolism, providing a mechanistic link between mtFAS and neurodegeneration.
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Affiliation(s)
- Debdeep Dutta
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Seul Kee Byeon
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
| | - Paul C Marcogliese
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
- Department of Biochemistry & Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Rishi V Shridharan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Jun Hyoung Park
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Guang Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Ming Ge
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Gali Heimer
- Pediatric Neurology Unit, Edmond and Lily Safra Children's Hospital, Sheba Medical Center, Ramat Gan, Israel
- The Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Jennefer N Kohler
- Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Matthew T Wheeler
- Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Benny A Kaipparettu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Akhilesh Pandey
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, USA
- Manipal Academy of Higher Education, Manipal, India
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA.
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7
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Lou X, Zhou Y, Liu Z, Xie Y, Zhang L, Zhao S, Gong S, Zhuo X, Wang J, Dai L, Ren X, Tong X, Jiang L, Fang H, Fang F, Lyu J. De novo frameshift variant in MT-ND1 causes a mitochondrial complex I deficiency associated with MELAS syndrome. Gene 2023; 860:147229. [PMID: 36717040 DOI: 10.1016/j.gene.2023.147229] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 01/04/2023] [Accepted: 01/24/2023] [Indexed: 01/29/2023]
Abstract
BACKGROUND The variant m.3571_3572insC/MT-ND1 thus far only reported in oncocytic tumors of different tissues. However, the role of m.3571_3572insC in inherited mitochondrial diseases has yet to be elucidated. METHODS A patient diagnosed with MELAS syndrome was recruited, and detailed medical records were collected and reviewed. The muscle was biopsied for mitochondrial respiratory chain enzyme activity. Series of fibroblast clones bearing different m.3571_3572insC variant loads were generated from patient-derived fibroblasts and subjected to functional assays. RESULTS Complex I deficiency was confirmed in the patient's muscle via mitochondrial respiratory chain enzyme activity assay. The m.3571_3572insC was filtered for the candidate variant of the patient according to the guidelines for mitochondrial mRNA variants interpretation. Three cell clones with different m.3571_3572insC variant loads were generated to evaluate mitochondrial function. Blue native PAGE analysis revealed that m.3571_3572insC caused a deficiency in the mitochondrial complex I. Oxygen consumption rate, ATP production, and lactate assays found an impairment of cellular bioenergetic capacity due to m.3571_3572insC. Mitochondrial membrane potential was decreased, and mitochondrial reactive oxygen species production was increased with the variant of m.3571_3572insC. According to the competitive cell growth assay, the mutant cells had impaired cell growth capacity compared to wild type. CONCLUSIONS A novel variant m.3571_3572insC was identified in a patient diagnosed with MELAS syndrome, and the variant impaired mitochondrial respiration by decreasing the activity of complex I. In conclusion, the genetic spectrum of mitochondrial diseases was expanded by including m.3571_3572insC/MT-ND1.
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Affiliation(s)
- Xiaoting Lou
- Center for Reproductive Medicine, Department of Genetic and Genomic Medicine, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang 310014, China; Laboratory Medicine Center, Department of Clinical Laboratory, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang 310014, China
| | - Yuwei Zhou
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Zhimei Liu
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100069, China
| | - Yaojun Xie
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Luyi Zhang
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Suzhou Zhao
- Fujungenetics Technologies Co., Ltd, Beijing 100176, China
| | - Shuai Gong
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100069, China
| | - Xiuwei Zhuo
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100069, China
| | - Junling Wang
- Department of Pediatrics, Third Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, China
| | - Lifang Dai
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100069, China
| | - Xiaotun Ren
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100069, China
| | - Xiao Tong
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100069, China
| | - Liangliang Jiang
- Pediatric Neurology, Anhui Provincial Children's Hospital, Hefei, Anhui 230022, China
| | - Hezhi Fang
- Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China
| | - Fang Fang
- Department of Neurology, Beijing Children's Hospital, Capital Medical University, National Center for Children's Health, Beijing 100069, China.
| | - Jianxin Lyu
- Laboratory Medicine Center, Department of Clinical Laboratory, Zhejiang Provincial People's Hospital, Affiliated People's Hospital, Hangzhou Medical College, Hangzhou, Zhejiang 310014, China; Key Laboratory of Laboratory Medicine, Ministry of Education, Zhejiang Provincial Key Laboratory of Medical Genetics, College of Laboratory Medicine and Life Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, China.
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8
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Webb BD, Nowinski SM, Solmonson A, Ganesh J, Rodenburg RJ, Leandro J, Evans A, Vu HS, Naidich TP, Gelb BD, DeBerardinis RJ, Rutter J, Houten SM. Recessive pathogenic variants in MCAT cause combined oxidative phosphorylation deficiency. eLife 2023; 12:e68047. [PMID: 36881526 PMCID: PMC9991045 DOI: 10.7554/elife.68047] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Accepted: 02/01/2023] [Indexed: 03/06/2023] Open
Abstract
Malonyl-CoA-acyl carrier protein transacylase (MCAT) is an enzyme involved in mitochondrial fatty acid synthesis (mtFAS) and catalyzes the transfer of the malonyl moiety of malonyl-CoA to the mitochondrial acyl carrier protein (ACP). Previously, we showed that loss-of-function of mtFAS genes, including Mcat, is associated with severe loss of electron transport chain (ETC) complexes in mouse immortalized skeletal myoblasts (Nowinski et al., 2020). Here, we report a proband presenting with hypotonia, failure to thrive, nystagmus, and abnormal brain MRI findings. Using whole exome sequencing, we identified biallelic variants in MCAT. Protein levels for NDUFB8 and COXII, subunits of complex I and IV respectively, were markedly reduced in lymphoblasts and fibroblasts, as well as SDHB for complex II in fibroblasts. ETC enzyme activities were decreased in parallel. Re-expression of wild-type MCAT rescued the phenotype in patient fibroblasts. This is the first report of a patient with MCAT pathogenic variants and combined oxidative phosphorylation deficiency.
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Affiliation(s)
- Bryn D Webb
- Department of Pediatrics and Center for Human Genomics and Precision Medicine, University of Wisconsin School of Medicine and Public HealthMadison, WIUnited States
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
- Department of Pediatrics, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
| | - Sara M Nowinski
- Department of Metabolism and Nutritional Programming, Van Andel InstituteGrand Rapids, MIUnited States
| | - Ashley Solmonson
- Children’s Medical Center Research Institute, University of Texas Southwestern Medical CenterDallas, TXUnited States
| | - Jaya Ganesh
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
| | - Richard J Rodenburg
- Department of Pediatrics, Nijmegen Center for Mitochondrial Disorders, Radboud University Medical CenterNijmegenNetherlands
| | - Joao Leandro
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
| | - Anthony Evans
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
| | - Hieu S Vu
- Children’s Medical Center Research Institute, University of Texas Southwestern Medical CenterDallas, TXUnited States
| | - Thomas P Naidich
- Department of Radiology, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
| | - Bruce D Gelb
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
- Department of Pediatrics, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
- Mindich Child Health and Development Institute, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
| | - Ralph J DeBerardinis
- Children’s Medical Center Research Institute, University of Texas Southwestern Medical CenterDallas, TXUnited States
- Howard Hughes Medical InstituteChevy Chase, MDUnited States
| | - Jared Rutter
- Howard Hughes Medical InstituteChevy Chase, MDUnited States
- Department of Biochemistry, University of UtahSalt Lake City, UTUnited States
| | - Sander M Houten
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount SinaiNew York, NYUnited States
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9
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Chander V, Mahmoud M, Hu J, Dardas Z, Grochowski CM, Dawood M, Khayat MM, Li H, Li S, Jhangiani S, Korchina V, Shen H, Weissenberger G, Meng Q, Gingras MC, Muzny DM, Doddapaneni H, Posey JE, Lupski JR, Sabo A, Murdock DR, Sedlazeck FJ, Gibbs RA. Long read sequencing and expression studies of AHDC1 deletions in Xia-Gibbs syndrome reveal a novel genetic regulatory mechanism. Hum Mutat 2022; 43:2033-2053. [PMID: 36054313 PMCID: PMC10167679 DOI: 10.1002/humu.24461] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 08/17/2022] [Accepted: 08/30/2022] [Indexed: 01/25/2023]
Abstract
Xia-Gibbs syndrome (XGS; MIM# 615829) is a rare mendelian disorder characterized by Development Delay (DD), intellectual disability (ID), and hypotonia. Individuals with XGS typically harbor de novo protein-truncating mutations in the AT-Hook DNA binding motif containing 1 (AHDC1) gene, although some missense mutations can also cause XGS. Large de novo heterozygous deletions that encompass the AHDC1 gene have also been ascribed as diagnostic for the disorder, without substantial evidence to support their pathogenicity. We analyzed 19 individuals with large contiguous deletions involving AHDC1, along with other genes. One individual bore the smallest known contiguous AHDC1 deletion (∼350 Kb), encompassing eight other genes within chr1p36.11 (Feline Gardner-Rasheed, IFI6, FAM76A, STX12, PPP1R8, THEMIS2, RPA2, SMPDL3B) and terminating within the first intron of AHDC1. The breakpoint junctions and phase of the deletion were identified using both short and long read sequencing (Oxford Nanopore). Quantification of RNA expression patterns in whole blood revealed that AHDC1 exhibited a mono-allelic expression pattern with no deficiency in overall AHDC1 expression levels, in contrast to the other deleted genes, which exhibited a 50% reduction in mRNA expression. These results suggest that AHDC1 expression in this individual is compensated by a novel regulatory mechanism and advances understanding of mutational and regulatory mechanisms in neurodevelopmental disorders.
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Affiliation(s)
- Varuna Chander
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Medhat Mahmoud
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Jianhong Hu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Zain Dardas
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | | | - Moez Dawood
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Michael M. Khayat
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - He Li
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Shoudong Li
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Shalini Jhangiani
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Viktoriya Korchina
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Hua Shen
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | | | - Qingchang Meng
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Marie-Claude Gingras
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Donna M. Muzny
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Harsha Doddapaneni
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - Jennifer E. Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - James R. Lupski
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Texas Children’s Hospital, Houston, Texas, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Aniko Sabo
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
| | - David R. Murdock
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Fritz J. Sedlazeck
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
- Department of Computer Science, Rice University, Houston, Texas, USA
| | - Richard A. Gibbs
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, Texas, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
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