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Wortmann SB, Oud MM, Alders M, Coene KLM, van der Crabben SN, Feichtinger RG, Garanto A, Hoischen A, Langeveld M, Lefeber D, Mayr JA, Ockeloen CW, Prokisch H, Rodenburg R, Waterham HR, Wevers RA, van de Warrenburg BPC, Willemsen MAAP, Wolf NI, Vissers LELM, van Karnebeek CDM. How to proceed after "negative" exome: A review on genetic diagnostics, limitations, challenges, and emerging new multiomics techniques. J Inherit Metab Dis 2022; 45:663-681. [PMID: 35506430 PMCID: PMC9539960 DOI: 10.1002/jimd.12507] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 04/26/2022] [Accepted: 04/27/2022] [Indexed: 11/28/2022]
Abstract
Exome sequencing (ES) in the clinical setting of inborn metabolic diseases (IMDs) has created tremendous improvement in achieving an accurate and timely molecular diagnosis for a greater number of patients, but it still leaves the majority of patients without a diagnosis. In parallel, (personalized) treatment strategies are increasingly available, but this requires the availability of a molecular diagnosis. IMDs comprise an expanding field with the ongoing identification of novel disease genes and the recognition of multiple inheritance patterns, mosaicism, variable penetrance, and expressivity for known disease genes. The analysis of trio ES is preferred over singleton ES as information on the allelic origin (paternal, maternal, "de novo") reduces the number of variants that require interpretation. All ES data and interpretation strategies should be exploited including CNV and mitochondrial DNA analysis. The constant advancements in available techniques and knowledge necessitate the close exchange of clinicians and molecular geneticists about genotypes and phenotypes, as well as knowledge of the challenges and pitfalls of ES to initiate proper further diagnostic steps. Functional analyses (transcriptomics, proteomics, and metabolomics) can be applied to characterize and validate the impact of identified variants, or to guide the genomic search for a diagnosis in unsolved cases. Future diagnostic techniques (genome sequencing [GS], optical genome mapping, long-read sequencing, and epigenetic profiling) will further enhance the diagnostic yield. We provide an overview of the challenges and limitations inherent to ES followed by an outline of solutions and a clinical checklist, focused on establishing a diagnosis to eventually achieve (personalized) treatment.
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Affiliation(s)
- Saskia B. Wortmann
- Radboud Center for Mitochondrial and Metabolic Medicine, Department of PediatricsAmalia Children's Hospital, Radboud University Medical CenterNijmegenThe Netherlands
- University Children's Hospital, Paracelsus Medical UniversitySalzburgAustria
| | - Machteld M. Oud
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Department of Human GeneticsDonders Institute for Brain, Cognition and Behaviour, Radboud University Medical CenterNijmegenThe Netherlands
| | - Mariëlle Alders
- Department of Human GeneticsAmsterdam UMC, University of Amsterdam, Amsterdam Reproduction and Development Research InstituteAmsterdamThe Netherlands
| | - Karlien L. M. Coene
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Saskia N. van der Crabben
- Department of Human GeneticsAmsterdam University Medical Centers, University of AmsterdamAmsterdamThe Netherlands
| | - René G. Feichtinger
- University Children's Hospital, Paracelsus Medical UniversitySalzburgAustria
| | - Alejandro Garanto
- Radboud Center for Mitochondrial and Metabolic Medicine, Department of PediatricsAmalia Children's Hospital, Radboud University Medical CenterNijmegenThe Netherlands
- Department of PediatricsAmalia Children's Hospital, Radboud Institute for Molecular LifesciencesNijmegenThe Netherlands
- Department of Human GeneticsRadboud Institute for Molecular LifesciencesNijmegenThe Netherlands
| | - Alex Hoischen
- Department of Human Genetics, Department of Internal Medicine and Radboud Center for Infectious DiseasesRadboud Institute of Medical Life Sciences, Radboud University Medical CenterNijmegenthe Netherlands
| | - Mirjam Langeveld
- Department of Endocrinology and MetabolismAmsterdam University Medical Centers, location AMC, University of AmsterdamAmsterdamThe Netherlands
| | - Dirk Lefeber
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
- Department of Neurology, Donders Institute for BrainCognition and Behaviour, Radboud University Medical CenterNijmegenThe Netherlands
| | - Johannes A. Mayr
- University Children's Hospital, Paracelsus Medical UniversitySalzburgAustria
| | - Charlotte W. Ockeloen
- Department of Human GeneticsRadboud Institute for Molecular LifesciencesNijmegenThe Netherlands
| | - Holger Prokisch
- School of MedicineInstitute of Human Genetics, Technical University Munich and Institute of NeurogenomicsNeuherbergGermany
| | - Richard Rodenburg
- Radboud Center for Mitochondrial and Metabolic MedicineTranslational Metabolic Laboratory, Department of Pediatrics, Radboud University Medical CenterNijmegenThe Netherlands
| | - Hans R. Waterham
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Laboratory Genetic Metabolic Diseases, Department of Clinical ChemistryAmsterdam University Medical Centers, location AMC, University of AmsterdamAmsterdamThe Netherlands
| | - Ron A. Wevers
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Translational Metabolic Laboratory, Department of Laboratory MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Bart P. C. van de Warrenburg
- Department of Neurology, Donders Institute for BrainCognition and Behaviour, Radboud University Medical CenterNijmegenThe Netherlands
| | - Michel A. A. P. Willemsen
- Departments of Pediatric Neurology and PediatricsAmalia Children's Hospital, Donders Institute for Brain, Cognition and Behavior, Radboud University Medical CenterNijmegenThe Netherlands
| | - Nicole I. Wolf
- Amsterdam Leukodystrophy Center, Department of Child NeurologyEmma Children's Hospital, Amsterdam University Medical Centers, Vrije Universiteit AmsterdamAmsterdamThe Netherlands
| | - Lisenka E. L. M. Vissers
- Department of Human GeneticsDonders Institute for Brain, Cognition and Behaviour, Radboud University Medical CenterNijmegenThe Netherlands
| | - Clara D. M. van Karnebeek
- Radboud Center for Mitochondrial and Metabolic Medicine, Department of PediatricsAmalia Children's Hospital, Radboud University Medical CenterNijmegenThe Netherlands
- United for Metabolic DiseasesAmsterdamThe Netherlands
- Department of Human GeneticsAmsterdam UMC, University of Amsterdam, Amsterdam Reproduction and Development Research InstituteAmsterdamThe Netherlands
- Department of Pediatrics, Emma Center for Personalized MedicineAmsterdam University Medical Centers, Amsterdam, Amsterdam Genetics Endocrinology Metabolism Research Institute, University of AmsterdamAmsterdamThe Netherlands
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Goldstein ED, Cannistraro R, Atwal PS, Meschia JF. Undiagnosed Partial Ornithine Transcarbamylase Deficiency Presenting Postoperatively as Agitated Delirium. Neurohospitalist 2017; 8:82-85. [PMID: 29623158 DOI: 10.1177/1941874417729983] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Partial ornithine transcarbamylase deficiency (pOTCD), an enzymatic defect within the urea cycle, is an increasingly recognized etiology for hyperammonemia of unclear source following a stressor within female adults. Here we present a case of newly diagnosed pOTCD following a systemic stressor and prolonged hospitalization course. From a neurological perspective, prompt recognition provided the patient with a swift and near complete recovery. We briefly review the pertinent literature pertaining to this genetically based condition including historical context and current therapeutic approaches. Given the potential morbidity of prolonged hyperammonemia, neurohospitalists need to be aware of partial ornithine transcarbamylase as an entity.
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Affiliation(s)
- E D Goldstein
- Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
| | - R Cannistraro
- Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
| | - P S Atwal
- Department of Clinical Genomics Mayo Clinic, Jacksonville, FL, USA
| | - J F Meschia
- Department of Neurology, Mayo Clinic, Jacksonville, FL, USA
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Niu YF, Ni W, Wu ZY. ABCD1 mutations and phenotype distribution in Chinese patients with X-linked adrenoleukodystrophy. Gene 2013; 522:117-20. [PMID: 23566833 DOI: 10.1016/j.gene.2013.03.067] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2012] [Revised: 01/31/2013] [Accepted: 03/15/2013] [Indexed: 11/28/2022]
Abstract
X-linked adrenoleukodystrophy (X-ALD) is a neurodegenerative disorder resulting from mutations within the ABCD1 gene. Adrenomyeloneuropathy (AMN) and childhood cerebral ALD (CCALD) are most common phenotypes in the Western ALD patients. Here we performed mutation analysis of ABCD1 in 10 Chinese ALD families and identified 8 mutations, including one novel deletion (c.1477_1488+11del23) and 7 known mutations. Mutations c.1772G>A and c.1816T>C were first reported in the Chinese patients. Mutations c.1661G>A and c.1679C>T were demonstrated to be de novo mutations. The dinucleotide deletion 1415_16delAG, described as a mutational hotspot in different ethnic groups, was identified in two families. In addition, we performed a retrospective nation-wide mutation study of X-linked ALD in China based on a literature review. The retrospective study further confirmed the hypothesis that exon 6 is a potential mutation cluster region in the Asian populations. Furthermore, it suggested that CCALD is the most common phenotype in China.
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Affiliation(s)
- Yan-Fang Niu
- Department of Neurology and Institute of Neurology, Huashan Hospital, Shanghai Medical College, Fudan University, Shanghai, China
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Somatic gene mutation and human disease other than cancer: An update. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2010; 705:96-106. [DOI: 10.1016/j.mrrev.2010.04.002] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/29/2010] [Accepted: 04/08/2010] [Indexed: 12/24/2022]
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Chang B, Momoi N, Shan L, Mitomo M, Aoyagi Y, Endo K, Takeda I, Chen R, Xing Y, Yu X, Watanabe S, Yoshida T, Kanegane H, Tsubata S, Bowles NE, Ichida F, Miyawaki T. Gonadal mosaicism of a TAZ (G4.5) mutation in a Japanese family with Barth syndrome and left ventricular noncompaction. Mol Genet Metab 2010; 100:198-203. [PMID: 20303308 DOI: 10.1016/j.ymgme.2010.02.021] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 02/24/2010] [Accepted: 02/25/2010] [Indexed: 11/18/2022]
Abstract
TAZ (G4.5) was initially identified as the gene associated with Barth syndrome and left ventricular noncompaction (LVNC). The purpose of this study was to investigate patients with LVNC for disease-causing mutations in TAZ. In 124 Japanese patients, including 50 families, mutation analysis of TAZ was performed using DNA sequencing. A splice donor mutation was identified in two brothers with Barth syndrome and LVNC, and a sister who was asymptomatic. However, the variant was not identified in either parent or the maternal grandparents, all of whom were asymptomatic. Due to the recurrent inheritance of this variant by each of the children we concluded that this was evidence of gonadal mosaicism in the obligate carrier mother, the first reported occurrence of this in Barth syndrome.
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Affiliation(s)
- Bo Chang
- Department of Pediatrics, Toyama University, Sugitani, Toyama, Japan
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Grünewald S, Fairbanks L, Genet S, Cranston T, Hüsing J, Leonard JV, Champion MP. How reliable is the allopurinol load in detecting carriers for ornithine transcarbamylase deficiency? J Inherit Metab Dis 2004; 27:179-86. [PMID: 15159648 DOI: 10.1023/b:boli.0000028727.77454.bd] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The allopurinol test aims to distinguish carriers and noncarriers for ornithine transcarbamylase (OTC) deficiency. We have evaluated the reliability of the test in at-risk females of known genotype. Results based on urine orotidine and/or orotic acid measurement were compared in terms of sensitivity and specificity. Retrospectively, we analysed the results of allopurinol tests in 42 women (22 confirmed heterozygotes and 20 noncarriers) from 23 pedigrees at risk of being carriers for OTC deficiency. Using a cut-off of 2 standard deviations above the mean of controls, the highest sensitivity (91%) was given by orotidine alone or in combination with orotic acid, but specificity was only 70% and 65%, respectively. We conclude that the value of the allopurinol test for detecting OTC carriers in at-risk females is limited. This needs to be recognized when counselling families. The test still has a role as a safe, quick, noninvasive screen of individuals at risk, but test results in possible carriers should be interpreted with caution. In the absence of other supportive evidence, confirmation by mutation analysis is required.
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Abstract
The symptoms and signs of ornithine transcarbamylase deficiency are discussed. When the condition occurs among males in the neonatal period it is likely to be lethal. Pathological findings are non-specific. The diagnosis should be considered if coma with cerebral oedema and respiratory alkalosis occurs for no obvious reason. When hyperammonaemia is found, enzyme assay on a liver biopsy should be considered. A useful clue in an asymptomatic patient is a voluntary adoption of a vegetarian diet. Provocative tests, such as the allopurinol test can be used, but the method most frequently applied is mutation analysis. In the case of prenatal diagnosis this is possible on a chorionic villus sample. The prognosis of ornithine transcarbamylase deficiency is better for those with an onset after infancy, but morbidity from brain damage does not appear to be linked to the number of episodes of hyperammonaemia that have occurred. The syndrome results from a deficiency of the mitochondrial enzyme ornithine transcarbamylase which catalyses the conversion of ornithine and carbamoyl phosphate to citrulline. The gene responsible for this enzyme is located on Xp21.1, and is expressed in the liver and gut. Mutations can be divided into two groups: those with neonatal onset with all enzyme activity abolished, and those with later onset with partial and varying enzyme deficiency. There can be a variety of precipitating causes, for example sodium valproate. Treatment can be given with a low protein diet, and with alternate pathway drugs such as sodium benzoate and phenylbutyrate. Liver transplant can be considered when symptoms are life-threatening, although there may be severe complications.Gene replacement therapy is the hope of the future.
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Dvoráková L, Storkánová G, Unterrainer G, Hujová J, Kmoch S, Zeman J, Hrebícek M, Berger J. Eight novel ABCD1 gene mutations and three polymorphisms in patients with X-linked adrenoleukodystrophy: The first polymorphism causing an amino acid exchange. Hum Mutat 2002; 18:52-60. [PMID: 11438993 DOI: 10.1002/humu.1149] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
X-ALD is a neurological disorder associated with inherited defects in the ABCD1 (ALD) gene located on Xq28 and with impaired peroxisomal very long-chain fatty acid beta-oxidation. We examined the ABCD1 gene in probands from 11 unrelated X-ALD Czech and Slovak families by the direct sequencing of cDNA or genomic PCR products. In 10 families there were 10 different mutations, eight of which were novel. The spectrum of mutations consists of six point mutations, three microdeletions (1bp, 2bp, 4 bp), and one large deletion (229bp). In the 11th family we detected two novel single-base pair substitutions in exon 1 (c.38 A>C and c.649 A>G), both causing amino acid exchanges (N13T and K217E). Expression studies revealed that only K217E is a deleterious mutation, because a plasmid encoding ALDP with K217E was ineffective in the restoration of defective beta-oxidation in X-ALD fibroblasts. The N13T amino acid exchange, on the other hand, did not affect ALDP function. Thus, N13T represents the first polymorphism causing an amino acid exchange in the ABCD1 gene. As this polymorphism was observed neither in 100 control alleles nor in 300 X-ALD patients who have been sequenced so far world-wide, it seems to be very rare or unique. Two additional novel polymorphisms were found by the sequencing of the ABCD1 gene from our patients: c.-59 C/T in the 5'untranslated region and c.2019 C/T (F673F) in exon 10. The frequencies of these two polymorphisms, were 11/150 and 2/150 control alleles, respectively.
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Affiliation(s)
- L Dvoráková
- Institute for Inherited Metabolic Disorders, First Faculty of Medicine and General Faculty Hospital, Prague, Czech Republic
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Kemp S, Pujol A, Waterham HR, van Geel BM, Boehm CD, Raymond GV, Cutting GR, Wanders RJ, Moser HW. ABCD1 mutations and the X-linked adrenoleukodystrophy mutation database: role in diagnosis and clinical correlations. Hum Mutat 2001; 18:499-515. [PMID: 11748843 DOI: 10.1002/humu.1227] [Citation(s) in RCA: 195] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene, which encodes a peroxisomal ABC half-transporter (ALDP) involved in the import of very long-chain fatty acids (VLCFA) into the peroxisome. The disease is characterized by a striking and unpredictable variation in phenotypic expression. Phenotypes include the rapidly progressive childhood cerebral form (CCALD), the milder adult form, adrenomyeloneuropathy (AMN), and variants without neurologic involvement. There is no apparent correlation between genotype and phenotype. In males, unambiguous diagnosis can be achieved by demonstration of elevated levels of VLCFA in plasma. In 15 to 20% of obligate heterozygotes, however, test results are false-negative. Therefore, mutation analysis is the only reliable method for the identification of heterozygotes. Since most X-ALD kindreds have a unique mutation, a great number of mutations have been identified in the ABCD1 gene in the last seven years. In order to catalog and facilitate the analysis of these mutations, we have established a mutation database for X-ALD ( http://www.x-ald.nl). In this review we report a detailed analysis of all 406 X-ALD mutations currently included in the database. Also, we present 47 novel mutations. In addition, we review the various X-ALD phenotypes, the different diagnostic tools, and the need for extended family screening for the identification of new patients.
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Affiliation(s)
- S Kemp
- Department of Clinical Chemistry, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, The Netherlands.
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Abstract
The molecular epidemiology of factor IX germline mutations in patients with hemophilia B has been studied in detail because it is an advantageous model for analyzing recent germline mutations in humans. It is estimated that mutations have been defined in the majority of nucleotides that are the target for mutation. The likelihood that a factor IX missense mutation will cause disease correlates with the degree of evolutionary conservation of the amino acid. Mutation rates per base-pair have been estimated after careful consideration and correction for biases, predicting about 76 de novo mutations per generation per individual resulting in 0.3 deleterious changes. The male-to-female sex ratio of mutation varies with the type of mutation. There is evidence for a maternal age effect and an excess of non-CpG G:C to A:T transitions. The factor IX mutation pattern is similar among geographically, racially and ethnically diverse human populations. The data support primarily endogenous mechanisms of germline mutation in the factor IX gene. Mutations at splice junctions are compatible with simple rules for predicting disease causing mutations.
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Affiliation(s)
- S S Sommer
- Department of Molecular Genetics, Beckman Research Institute, 1450 East Duarte Road, City of Hope, Duarte, CA 91010-0269, USA.
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