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Dvaladze A, Tavares E, Di Scipio M, Nimmo G, Grudzinska-Pechhacker MK, Paton T, Tumber A, Li S, Eileen C, Ertl-Wagner B, Mamak E, Hoffmann G, Marshall CR, Haas D, Mayatepek E, Schulze A, Heon E, Vincent A. Deep Intronic Variant in MVK as a Cause for Mevalonic Aciduria Initially Presenting as Non-syndromic Retinitis Pigmentosa. Clin Genet 2022; 102:524-529. [PMID: 35916082 DOI: 10.1111/cge.14207] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 07/25/2022] [Accepted: 07/27/2022] [Indexed: 11/29/2022]
Abstract
Non-syndromic retinitis pigmentosa (NSRP) is a clinically and genetically heterogeneous group of disorders characterized by progressive degeneration of the rod and cone photoreceptors, often leading to blindness. The evolving association of syndromic genes to cause NSRP and the increasing role of intronic variants in explaining missing heritability in genetic disorders present challenges in establishing conclusive clinical and genetic diagnoses. This study sought to identify and validate the causative genetic variant(s) in a 13-year-old male initially diagnosed with NSRP. Genome sequencing identified a pathogenic missense variant in MVK [NM_000431.3:c.803T>C (p. Ile268Thr)], in trans with a novel intronic variant predicted to create a new donor splice site (c.768+71C>A). Proband cDNA analysis confirmed the inclusion of the first 68 base pairs of intron 8 that resulted in a frameshift in MVK (r.768_769ins[768+1_768+68]) and significantly reduced the expression of reference transcript (17.6%). Patient re-phenotyping revealed ataxia, cerebellar atrophy, elevated urinary mevalonate and LTE4 , in keeping with mild mevalonic aciduria and associated syndromic retinitis pigmentosa. Leakage of reference transcript likely explains the milder phenotype observed. This is the first association of a deep intronic splice variant to cause MVK-related disorder. This report highlights the importance of variant validation and patient re-phenotyping in establishing accurate diagnosis in the era of genome sequencing.
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Affiliation(s)
- Anna Dvaladze
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Erika Tavares
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Matteo Di Scipio
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Graeme Nimmo
- Clinical and Metabolic Genetics, HSC, Canada.,Fred A Litwin Family Centre for Genetic Medicine, The University Health Network, Toronto, Canada
| | - Monika K Grudzinska-Pechhacker
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada.,Department of Ophthalmology and Vision Sciences, HSC and University of Toronto, Canada
| | - Tara Paton
- The Centre for Applied Genomics, HSC, Canada
| | - Anupreet Tumber
- Department of Ophthalmology and Vision Sciences, HSC and University of Toronto, Canada
| | - Shuning Li
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Christabel Eileen
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada
| | - Birgit Ertl-Wagner
- Division of Neuroradiology, HSC, Canada.,Department of Medical Imaging, University of Toronto, Canada
| | - Eva Mamak
- Department of Psychology, HSC, Canada
| | - Georg Hoffmann
- Neuropaediatrics and Paediatric Metabolic Medicine, University Hospital Heidelberg, Germany
| | | | - Dorothea Haas
- Neuropaediatrics and Paediatric Metabolic Medicine, University Hospital Heidelberg, Germany
| | - Ertan Mayatepek
- Department of General Paediatrics, Neonatology and Paediatric Cardiology, University Children's Hospital, Heinrich Heine University, Dusseldorf, Germany
| | - Andreas Schulze
- Clinical and Metabolic Genetics, HSC, Canada.,Department of Paediatrics, University of Toronto, Canada.,Department of Biochemistry, University of Toronto, Canada
| | - Elise Heon
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada.,Department of Ophthalmology and Vision Sciences, HSC and University of Toronto, Canada
| | - Ajoy Vincent
- Genetics and Genome Biology, The Hospital for Sick Children (HSC), Toronto, Canada.,Department of Ophthalmology and Vision Sciences, HSC and University of Toronto, Canada
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2
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Haas D, Hoffmann GF. Mevalonate kinase deficiencies: from mevalonic aciduria to hyperimmunoglobulinemia D syndrome. Orphanet J Rare Dis 2006; 1:13. [PMID: 16722536 PMCID: PMC1475558 DOI: 10.1186/1750-1172-1-13] [Citation(s) in RCA: 130] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2006] [Accepted: 04/26/2006] [Indexed: 11/13/2022] Open
Abstract
Mevalonic aciduria (MVA) and hyperimmunoglobulinemia D syndrome (HIDS) represent the two ends of a clinical spectrum of disease caused by deficiency of mevalonate kinase (MVK), the first committed enzyme of cholesterol biosynthesis. At least 30 patients with MVA and 180 patients with HIDS have been reported worldwide. MVA is characterized by psychomotor retardation, failure to thrive, progressive cerebellar ataxia, dysmorphic features, progressive visual impairment and recurrent febrile crises. The febrile episodes are commonly accompanied by hepatosplenomegaly, lymphadenopathy, abdominal symptoms, arthralgia and skin rashes. Life expectancy is often compromised. In HIDS, only febrile attacks are present, but a subgroup of patients may also develop neurological abnormalities of varying degree such as mental retardation, ataxia, ocular symptoms and epilepsy. A reduced activity of MVK and pathogenic mutations in the MVK gene have been demonstrated as the common genetic basis in both disorders. In MVA, the diagnosis is established by detection of highly elevated levels of mevalonic acid excreted in urine. Increased levels of immunoglobulin D (IgD) and, in most patients of immunoglobulin A (IgA), in combination with enhanced excretion of mevalonic acid provide strong evidence for HIDS. The diagnosis is confirmed by low activity of mevalonate kinase or by demonstration of disease-causing mutations. Genetic counseling should be offered to families at risk. There is no established successful treatment for MVA. Simvastatin, an inhibitor of HMG-CoA reductase, and anakinra have been shown to have beneficial effect in HIDS.
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Affiliation(s)
- Dorothea Haas
- Department of General Pediatrics, University Children's Hospital Heidelberg, Im Neuenheimer Feld 150, D-69120 Heidelberg, Germany
| | - Georg F Hoffmann
- Department of General Pediatrics, University Children's Hospital Heidelberg, Im Neuenheimer Feld 150, D-69120 Heidelberg, Germany
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Mayatepek E, Ferdinandusse S, Meissner T, Wanders RJA. Analysis of cysteinyl leukotrienes and their metabolites in bile of patients with peroxisomal or mitochondrial β-oxidation defects. Clin Chim Acta 2004; 345:89-92. [PMID: 15193981 DOI: 10.1016/j.cccn.2004.03.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2004] [Revised: 03/02/2004] [Accepted: 03/02/2004] [Indexed: 11/29/2022]
Abstract
Cysteinyl leukotrienes (LTs) are potent lipid mediators which are predominantly eliminated via bile. Their metabolic inactivation and degradation proceeds by beta-oxidation. However, although bile is the optimal material for analysis of LTs in man, only very sparse data on bile LT concentration under normal or pathophysiological conditions exist. The aim of the present study was to present for the first time a complete profile of endogenous LTs in human bile and to investigate the importance of bile LT analysis in peroxisomal and mitochondrial beta-oxidation deficiency. Cysteinyl LTs and their oxidation metabolites were analysed after HPLC separation by specific immunoassays or gas chromatography-mass spectrometry. Under physiological conditions, LTs are found in human bile (n = 8) in the nanomolar range with LTD4 predominating, whereas the other LTs were present in similar amounts. In bile of a patient with a peroxisome biogenesis disorder (Zellweger syndrome, ZS) LTE(4) was found to be slightly increased, whereas both omega-oxidation metabolites of LTE4, omega-hydroxy-LTE4 and omega-carboxy-LTE4, were highly increased (about 12-18 times). The beta-oxidation metabolite omega-carboxy-tetranor-LTE3 was below the detection limit (< 0.1 nmol/l; controls 1.4 +/- 1.2 nmol/l). This abnormal profile demonstrates an impaired degradation of LTs in ZS. In contrast, patients with X-linked adrenoleukodystrophy (X-ALD), medium-chain acyl CoA dehydrogenase deficiency (MCAD) as well as very long-chain acyl CoA dehydrogenase deficiency (VLCAD) did not show any differences in their biliary profile of LTs compared to controls. Increased levels of the biologically active cysteinyl LTs in the bile of patients with ZS might be of pathophysiological significance in the course of the disease, e.g. contributing to liver injury. In addition, our data confirm that the beta-oxidation of cysteinyl LTs in vivo occurs in peroxisomes and not in mitochondria.
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Affiliation(s)
- Ertan Mayatepek
- Department of General Pediatrics, University Children's Hospital, Moorenstrasse 5, D-40225, Düsseldorf, Germany.
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Abstract
The known disorders of cholesterol biosynthesis have expanded rapidly since the discovery that Smith-Lemli-Opitz syndrome is caused by a deficiency of 7-dehydrocholesterol. Each of the six now recognized sterol disorders-mevalonic aciduria, Smith-Lemli-Opitz syndrome, desmosterolosis, Conradi-Hünermann syndrome, CHILD syndrome, and Greenberg dysplasia-has added to our knowledge of the relationship between cholesterol metabolism and embryogenesis. One of the most important lessons learned from the study of these disorders is that abnormal cholesterol metabolism impairs the function of the hedgehog class of embryonic signaling proteins, which help execute the vertebrate body plan during the earliest weeks of gestation. The study of the enzymes and genes in these several syndromes has also expanded and better delineated an important class of enzymes and proteins with diverse structural functions and metabolic actions that include sterol biosynthesis, nuclear transcriptional signaling, regulation of meiosis, and even behavioral modulation.
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Affiliation(s)
- R I Kelley
- Kennedy Krieger Institute, Baltimore Maryland 21205, USA.
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Frenkel J, Willemsen MA, Weemaes CM, Dorland L, Mayatepek E. Increased urinary leukotriene E(4) during febrile attacks in the hyperimmunoglobulinaemia D and periodic fever syndrome. Arch Dis Child 2001; 85:158-9. [PMID: 11466192 PMCID: PMC1718877 DOI: 10.1136/adc.85.2.158] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND The hyperimmunoglobulinaemia D and periodic fever syndrome is a hereditary periodic fever, caused by deficiency of the enzyme mevalonate kinase. It is unclear how this defect leads to recurrent fever episodes. AIM To assess the involvement of cysteinyl leukotrienes in the pathogenesis of fever attacks as reflected by urinary leukotriene E(4) (LTE(4)) excretion. METHODS Urinary LTE(4) was measured in seven patients while febrile and afebrile. RESULTS LTE(4) was raised during fever in all subjects (46-199 nmol/mol creatinine, mean 92; normal <40). Urinary LTE(4) was normal between attacks, as well as in normal children with fever as a result of miscellaneous causes. CONCLUSION Our results suggest that cysteinyl leukotrienes play a role in the pathophysiology of this disorder. As no effective treatment is yet available, leukotriene receptor antagonists might offer a new therapeutic approach for patients with the hyperimmunoglobulinaemia D and periodic fever syndrome.
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Affiliation(s)
- J Frenkel
- Department of General Pediatrics, Wilhelmina Children's Hospital, KE.04.133.1, University Medical Center Utrecht, PO Box 85090, 3580AB Utrecht, Netherlands.
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Mayatepek E, Zelezny R, Hoffmann GF. Analysis of leukotrienes in cerebrospinal fluid of a reference population and patients with inborn errors of metabolism: further evidence for a pathognomonic profile in LTC(4)-synthesis deficiency. Clin Chim Acta 2000; 292:155-62. [PMID: 10686285 DOI: 10.1016/s0009-8981(99)00216-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Cysteinyl leukotrienes (LTC(4), LTD(4), LTE(4)) are potent lipid mediators derived from arachidonate in the 5-lipoxygenase pathway. Recently, the first inborn error of leukotriene synthesis, LTC(4)-synthesis deficiency, has been identified in association with a fatal developmental syndrome. The absence of leukotrienes in cerebrospinal fluid was one of the most striking biochemical findings in this disorder. We analysed leukotrienes in cerebrospinal fluid of patients with a broad spectrum of other well-defined inborn errors of metabolism, including glutathione synthetase deficiency (n=2), Zellweger syndrome (n=3), mitochondrial disorders (n=8), fatty acid oxidation defects (n=7), organic acidurias (n=7), neurotransmitter defects (n=5) and patients with non-specific neurological symptoms, as a reference population (n=120). The concentrations of leukotrienes were not related to age. Representative percentiles were calculated as reference intervals of each leukotriene. In all patients with an inborn error of metabolism concentration of cysteinyl leukotrienes and LTB(4) did not differ from the reference group. Our results indicate that absence of cysteinyl leukotrienes (<5 pg/ml) in association with normal or increased LTB(4) (50.0-67.3 pg/ml) is pathognomonic for LTC(4)-synthesis deficiency. The unique profile of leukotrienes in cerebrospinal fluid in this new disorder is primarily related to the defect and represents a new diagnostic approach.
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Affiliation(s)
- E Mayatepek
- Division of Metabolic Diseases, University Children's Hospital, Im Neuenheimer Feld 150, D-69120, Heidelberg, Germany.
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Kohlschütter A, Mayatepek E, Finckh B, Hübner C. Effect of plasma alpha-tocopherol on leukotriene E4 excretion in genetic vitamin E deficiency. J Inherit Metab Dis 1997; 20:581-6. [PMID: 9266396 DOI: 10.1023/a:1005311227094] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Studying the biological effects of vitamin e in humans is difficult because conditions involving vitamin E deficiency are usually associated with chronic multiple pathology. Genetic vitamin E deficiency caused by a deficient alpha-tocopherol transport protein offers unique possibilities for study of vitamin E effects since the patients can be studied in good general health. In such a patient we manipulated plasma alpha-tocopherol levels in a wide range by varying oral alpha-tocopherol supplements and measured urinary leukotriene E4 (LTE4) concentrations. LTE4 excretion proved inversely correlated to plasma alpha-tocopherol levels. This strongly suggests that in genetic vitamin E deficiency, alpha-tocopherol influences formation of leukotrienes in vivo.
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