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Niceta M, Ciolfi A, Ferilli M, Pedace L, Cappelletti C, Nardini C, Hildonen M, Chiriatti L, Miele E, Dentici ML, Gnazzo M, Cesario C, Pisaneschi E, Baban A, Novelli A, Maitz S, Selicorni A, Squeo GM, Merla G, Dallapiccola B, Tumer Z, Digilio MC, Priolo M, Tartaglia M. DNA methylation profiling in Kabuki syndrome: reclassification of germline KMT2D VUS and sensitivity in validating postzygotic mosaicism. Eur J Hum Genet 2024:10.1038/s41431-024-01597-9. [PMID: 38528056 DOI: 10.1038/s41431-024-01597-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Revised: 03/05/2024] [Accepted: 03/13/2024] [Indexed: 03/27/2024] Open
Abstract
Autosomal dominant Kabuki syndrome (KS) is a rare multiple congenital anomalies/neurodevelopmental disorder caused by heterozygous inactivating variants or structural rearrangements of the lysine-specific methyltransferase 2D (KMT2D) gene. While it is often recognizable due to a distinctive gestalt, the disorder is clinically variable, and a phenotypic scoring system has been introduced to help clinicians to reach a clinical diagnosis. The phenotype, however, can be less pronounced in some patients, including those carrying postzygotic mutations. The full spectrum of pathogenic variation in KMT2D has not fully been characterized, which may hamper the clinical classification of a portion of these variants. DNA methylation (DNAm) profiling has successfully been used as a tool to classify variants in genes associated with several neurodevelopmental disorders, including KS. In this work, we applied a KS-specific DNAm signature in a cohort of 13 individuals with KMT2D VUS and clinical features suggestive or overlapping with KS. We succeeded in correctly classifying all the tested individuals, confirming diagnosis for three subjects and rejecting the pathogenic role of 10 VUS in the context of KS. In the latter group, exome sequencing allowed to identify the genetic cause underlying the disorder in three subjects. By testing five individuals with postzygotic pathogenic KMT2D variants, we also provide evidence that DNAm profiling has power to recognize pathogenic variants at different levels of mosaicism, identifying 15% as the minimum threshold for which DNAm profiling can be applied as an informative diagnostic tool in KS mosaics.
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Affiliation(s)
- Marcello Niceta
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Andrea Ciolfi
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Marco Ferilli
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
- Department of Computer, Control and Management Engineering, Sapienza University, 00185, Rome, Italy
| | - Lucia Pedace
- Department of Pediatric Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, 00165, Rome, Italy
| | - Camilla Cappelletti
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Claudia Nardini
- Department of Pediatric Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, 00165, Rome, Italy
| | - Mathis Hildonen
- Department of Clinical Genetics, Kennedy Center, Copenhagen University Hospital, Rigshopsitalet, 2600, Glostrup, Denmark
| | - Luigi Chiriatti
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Evelina Miele
- Department of Pediatric Hematology/Oncology, Cell and Gene Therapy, Bambino Gesù Children's Hospital, IRCCS, 00165, Rome, Italy
| | - Maria Lisa Dentici
- Medical Genetics Unit, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Maria Gnazzo
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Claudia Cesario
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Elisa Pisaneschi
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Anwar Baban
- Pediatric Cardiology and Cardiac Arrhythmias Unit, Department of Pediatric Cardiology and Cardiac Surgery, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Antonio Novelli
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Silvia Maitz
- Genetica Clinica Pediatrica, Fondazione MBBM, ASST Monza Ospedale San Gerardo, 20900, Monza, Italy
| | | | - Gabriella Maria Squeo
- Laboratory of Regulatory and Functional Genomics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, 71013, Foggia, Italy
| | - Giuseppe Merla
- Laboratory of Regulatory and Functional Genomics, Fondazione IRCCS Casa Sollievo della Sofferenza, San Giovanni Rotondo, 71013, Foggia, Italy
- Department of Molecular Medicine and Medical Biotechnology, University of Naples Federico II, 80131, Naples, Italy
| | - Bruno Dallapiccola
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy
| | - Zeynep Tumer
- Department of Clinical Genetics, Kennedy Center, Copenhagen University Hospital, Rigshopsitalet, 2600, Glostrup, Denmark
- Department of Clinical Medicine, Faculty of Medicine and Health Sciences, University of Copenhagen, 2200, Copenhagen, Denmark
| | | | - Manuela Priolo
- Medical and Laboratory Genetics, Antonio Cardarelli Hospital, 80131, Naples, Italy
| | - Marco Tartaglia
- Molecular Genetics and Functional Genomics, Bambino Gesù Children's Hospital, IRCCS, 00146, Rome, Italy.
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Stoltze UK, Hildonen M, Hansen TVO, Foss-Skiftesvik J, Byrjalsen A, Lundsgaard M, Pignata L, Grønskov K, Tumer Z, Schmiegelow K, Brok JS, Wadt KAW. Germline (epi)genetics reveals high predisposition in females: a 5-year, nationwide, prospective Wilms tumour cohort. J Med Genet 2023; 60:842-849. [PMID: 37019617 PMCID: PMC10447365 DOI: 10.1136/jmg-2022-108982] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 03/10/2023] [Indexed: 04/07/2023]
Abstract
BACKGROUND Studies suggest that Wilms tumours (WT) are caused by underlying genetic (5%-10%) and epigenetic (2%-29%) mechanisms, yet studies covering both aspects are sparse. METHODS We performed prospective whole-genome sequencing of germline DNA in Danish children diagnosed with WT from 2016 to 2021, and linked genotypes to deep phenotypes. RESULTS Of 24 patients (58% female), 3 (13%, all female) harboured pathogenic germline variants in WT risk genes (FBXW7, WT1 and REST). Only one patient had a family history of WT (3 cases), segregating with the REST variant. Epigenetic testing revealed one (4%) additional patient (female) with uniparental disomy of chromosome 11 and Beckwith-Wiedemann syndrome (BWS). We observed a tendency of higher methylation of the BWS-related imprinting centre 1 in patients with WT than in healthy controls. Three patients (13%, all female) with bilateral tumours and/or features of BWS had higher birth weights (4780 g vs 3575 g; p=0.002). We observed more patients with macrosomia (>4250 g, n=5, all female) than expected (OR 9.98 (95% CI 2.56 to 34.66)). Genes involved in early kidney development were enriched in our constrained gene analysis, including both known (WT1, FBXW7) and candidate (CTNND1, FRMD4A) WT predisposition genes. WT predisposing variants, BWS and/or macrosomia (n=8, all female) were more common in female patients than male patients (p=0.01). CONCLUSION We find that most females (57%) and 33% of all patients with WT had either a genetic or another indicator of WT predisposition. This emphasises the need for scrutiny when diagnosing patients with WT, as early detection of underlying predisposition may impact treatment, follow-up and genetic counselling.
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Affiliation(s)
- Ulrik Kristoffer Stoltze
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
- Department of Pediatrics, Rigshospitalet, Copenhagen, Denmark
| | - Mathis Hildonen
- Department of Genetics, Kennedy Center-National Research Center on Rare Genetic Diseases, Glostrup, Denmark
| | | | | | - Anna Byrjalsen
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - Malene Lundsgaard
- Department of Clinical Genetics, Aalborg University Hospital, Aalborg, North Denmark Region, Denmark
| | - Laura Pignata
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, Università Degli Studi Della Campania "Luigi Vanvitelli", Caserta, Italy
| | - Karen Grønskov
- Department of Clinical Genetics, Rigshospitalet, Copenhagen, Denmark
| | - Zeynep Tumer
- Applied Human Molecular Genetics, Kennedy Center, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | | | - Jesper Sune Brok
- Department of Pediatrics and Adolescent Medicine, Rigshospitalet, Copenhagen, Denmark
| | - Karin A W Wadt
- Department of Clinical Genetics, University Hospital of Copenhagen, Copenhagen, Denmark
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Hildonen M, Ferilli M, Hjortshøj TD, Dunø M, Risom L, Bak M, Ek J, Møller RS, Ciolfi A, Tartaglia M, Tümer Z. DNA methylation signature classification of rare disorders using publicly available methylation data. Clin Genet 2023; 103:688-692. [PMID: 36705342 DOI: 10.1111/cge.14304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Revised: 01/18/2023] [Accepted: 01/19/2023] [Indexed: 01/28/2023]
Abstract
Disease-specific DNA methylation patterns (DNAm signatures) have been established for an increasing number of genetic disorders and represent a valuable tool for classification of genetic variants of uncertain significance (VUS). Sample size and batch effects are critical issues for establishing DNAm signatures, but their impact on the sensitivity and specificity of an already established DNAm signature has not previously been tested. Here, we assessed whether publicly available DNAm data can be employed to generate a binary machine learning classifier for VUS classification, and used variants in KMT2D, the gene associated with Kabuki syndrome, together with an existing DNAm signature as proof-of-concept. Using publicly available methylation data for training, a classifier for KMT2D variants was generated, and individuals with molecularly confirmed Kabuki syndrome and unaffected individuals could be correctly classified. The present study documents the clinical utility of a robust DNAm signature even for few affected individuals, and most importantly, underlines the importance of data sharing for improved diagnosis of rare genetic disorders.
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Affiliation(s)
- Mathis Hildonen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark
| | - Marco Ferilli
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Tina Duelund Hjortshøj
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Morten Dunø
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Lotte Risom
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Mads Bak
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Jakob Ek
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark
| | - Rikke S Møller
- Department of Epilepsy Genetics and Personalized Treatment, The Danish Epilepsy Centre, Dianalund, Denmark.,Department of Regional Health Research, University of Southern Denmark, Odense, Denmark
| | - Andrea Ciolfi
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Marco Tartaglia
- Molecular Genetics and Functional Genomics, Ospedale Pediatrico Bambino Gesù, IRCCS, Rome, Italy
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, Glostrup, Denmark.,Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Rasmussen A, Hildonen M, Vissing J, Duno M, Tümer Z, Birkedal U. High Resolution Analysis of DMPK Hypermethylation and Repeat Interruptions in Myotonic Dystrophy Type 1. Genes (Basel) 2022; 13:genes13060970. [PMID: 35741732 PMCID: PMC9222588 DOI: 10.3390/genes13060970] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 05/19/2022] [Accepted: 05/26/2022] [Indexed: 02/05/2023] Open
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystemic neuromuscular disorder caused by the expansion of a CTG repeat in the 3′-UTR of DMPK, which is transcribed to a toxic gain-of-function RNA that affects splicing of a range of genes. The expanded repeat is unstable in both germline and somatic cells. The variable age at disease onset and severity of symptoms have been linked to the inherited CTG repeat length, non-CTG interruptions, and methylation levels flanking the repeat. In general, the genetic biomarkers are investigated separately with specific methods, making it tedious to obtain an overall characterisation of the repeat for a given individual. In the present study, we employed Oxford nanopore sequencing in a pilot study to simultaneously determine the repeat lengths, investigate the presence and nature of repeat interruptions, and quantify methylation levels in the regions flanking the CTG-repeats in four patients with DM1. We determined the repeat lengths, and in three patients, we observed interruptions which were not detected using repeat-primed PCR. Interruptions may thus be more common than previously anticipated and should be investigated in larger cohorts. Allele-specific analyses enabled characterisation of aberrant methylation levels specific to the expanded allele, which greatly increased the sensitivity and resolved cases where the methylation levels were ambiguous.
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Affiliation(s)
- Astrid Rasmussen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
| | - Mathis Hildonen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
| | - John Vissing
- Copenhagen Neuromuscular Center, Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Morten Duno
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Correspondence:
| | - Ulf Birkedal
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (A.R.); (M.H.); (U.B.)
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Hildonen M, Levy AM, Dahl C, Bjerregaard VA, Birk Møller L, Guldberg P, Debes NM, Tümer Z. Elevated Expression of SLC6A4 Encoding the Serotonin Transporter (SERT) in Gilles de la Tourette Syndrome. Genes (Basel) 2021; 12:86. [PMID: 33445578 PMCID: PMC7827645 DOI: 10.3390/genes12010086] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 01/02/2023] Open
Abstract
Gilles de la Tourette syndrome (GTS) is a complex neurodevelopmental disorder characterized by motor and vocal tics. Most of the GTS individuals have comorbid diagnoses, of which obsessive-compulsive disorder (OCD) and attention deficit-hyperactivity disorder (ADHD) are the most common. Several neurotransmitter systems have been implicated in disease pathogenesis, and amongst these, the dopaminergic and the serotonergic pathways are the most widely studied. In this study, we aimed to investigate whether the serotonin transporter (SERT) gene (SLC6A4) was differentially expressed among GTS individuals compared to healthy controls, and whether DNA variants (the SERT-linked polymorphic region 5-HTTLPR, together with the associated rs25531 and rs25532 variants, and the rare Ile425Val variant) or promoter methylation of SLC6A4 were associated with gene expression levels or with the presence of OCD as comorbidity. We observed that SLC6A4 expression is upregulated in GTS individuals compared to controls. Although no specific genotype, allele or haplotype was overrepresented in GTS individuals compared to controls, we observed that the LAC/LAC genotype of the 5-HTTLPR/rs25531/rs25532 three-locus haplotype was associated with higher SLC6A4 mRNA expression levels in GTS individuals, but not in the control group.
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Affiliation(s)
- Mathis Hildonen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (M.H.); (A.M.L.); (V.A.B.); (L.B.M.)
| | - Amanda M. Levy
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (M.H.); (A.M.L.); (V.A.B.); (L.B.M.)
| | - Christina Dahl
- Danish Cancer Society Research Center, 2100 Copenhagen, Denmark; (C.D.); (P.G.)
| | - Victoria A. Bjerregaard
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (M.H.); (A.M.L.); (V.A.B.); (L.B.M.)
| | - Lisbeth Birk Møller
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (M.H.); (A.M.L.); (V.A.B.); (L.B.M.)
- Institute for Nature, Systems and Models, Roskilde University Center, 4000 Roskilde, Denmark
| | - Per Guldberg
- Danish Cancer Society Research Center, 2100 Copenhagen, Denmark; (C.D.); (P.G.)
- Department of Cancer and Inflammation Research, Institute for Molecular Medicine, University of Southern Denmark, 5000 Odense, Denmark
| | - Nanette M. Debes
- Tourette Clinics, Department of Paediatrics, Copenhagen University Hospital, 2730 Herlev, Denmark;
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark; (M.H.); (A.M.L.); (V.A.B.); (L.B.M.)
- Deparment of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2020 Copenhagen, Denmark
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Hildonen M, Knak KL, Dunø M, Vissing J, Tümer Z. Stable Longitudinal Methylation Levels at the CpG Sites Flanking the CTG Repeat of DMPK in Patients with Myotonic Dystrophy Type 1. Genes (Basel) 2020; 11:genes11080936. [PMID: 32823742 PMCID: PMC7465187 DOI: 10.3390/genes11080936] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 08/10/2020] [Accepted: 08/10/2020] [Indexed: 12/11/2022] Open
Abstract
Myotonic dystrophy type 1 (DM1) is an autosomal dominant multisystem disorder mainly characterized by gradual muscle loss, weakness, and delayed relaxation after muscle contraction. It is caused by an expanded CTG repeat in the 3′ UTR of DMPK, which is transcribed into a toxic gain-of-function mRNA that affects the splicing of a range of other genes. The repeat is unstable, with a bias towards expansions both in somatic cells and in the germline, which results in a tendency for earlier onset with each generation, as longer repeat lengths generally correlate with earlier onset. Previous studies have found hypermethylation in the regions flanking the repeat in congenital onset DM1 and in some patients with non-congenital DM1. We used pyrosequencing to investigate blood methylation levels in 68 patients with non-congenital DM1, compare the methylation levels between the blood and muscle, and assess whether methylation levels change over time in the blood. We found higher methylation levels in the blood of DM1 patients than in healthy controls and especially in the patients who had inherited the disease allele maternally. The methylation levels remained relatively stable over time and are a strong biomarker of the disease, as well as of the maternal inheritance of the disease.
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Affiliation(s)
- Mathis Hildonen
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark;
| | - Kirsten Lykke Knak
- Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark; (K.L.K.); (J.V.)
| | - Morten Dunø
- Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark;
| | - John Vissing
- Department of Neurology, Copenhagen University Hospital, Rigshospitalet, 2100 Copenhagen, Denmark; (K.L.K.); (J.V.)
| | - Zeynep Tümer
- Kennedy Center, Department of Clinical Genetics, Copenhagen University Hospital, Rigshospitalet, 2600 Glostrup, Denmark;
- Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
- Correspondence: ; Tel.: +45-2920-4855
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Hildonen M, Kodama M, Puetz LC, Gilbert MTP, Limborg MT. A comparison of storage methods for gut microbiome studies in teleosts: Insights from rainbow trout (Oncorhynchus mykiss). J Microbiol Methods 2019; 160:42-48. [PMID: 30885689 DOI: 10.1016/j.mimet.2019.03.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 03/12/2019] [Indexed: 12/30/2022]
Abstract
Immediate freezing is perhaps the most preferred method used for preserving gut microbial samples, but research on sample preservation has been principally based around samples from mammalian species, and little is known about the advantages or disadvantages relating to different storage methods for fish guts. Fish gut samples may pose additional challenges due to the different chemical and enzymatic profile, as well as the higher water content, which might affect the yield and purity of DNA recovered. To explore this, we took gut content and mucosal scrape samples from 10 rainbow trout (Oncorhynchus mykiss), and tested whether different preservation methods have any effect on the ability to construct high quality genomic libraries for shotgun and 16S rRNA gene sequencing. Four different storage methods were compared for the gut content samples (immediate freezing on dry ice, 96% ethanol, RNAlater and DNA/RNA shield), while two different methods were compared for mucosal scrape samples (96% ethanol and RNAlater). The samples were thereafter stored at -80 °C. Our findings concluded that 96% ethanol outperforms the other storage methods when considering DNA quantity, quality, cost and labor. Ethanol works consistently well for both gut content and mucosal scrape samples, and enables construction of DNA sequencing libraries of sufficient quantity and with a fragment length distribution suitable for shotgun sequencing. Two main conclusions from our study are i) sample storage optimisation is an important part of establishing a microbiome research program in a new species or sample type system, and ii) 96% ethanol is the preferred method for storing rainbow trout gut content and mucosal scrape samples.
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Affiliation(s)
- Mathis Hildonen
- National History Museum of Denmark, University of Copenhagen, DK-1350 Copenhagen, Denmark
| | - Miyako Kodama
- National History Museum of Denmark, University of Copenhagen, DK-1350 Copenhagen, Denmark
| | - Lara C Puetz
- National History Museum of Denmark, University of Copenhagen, DK-1350 Copenhagen, Denmark
| | - M Thomas P Gilbert
- National History Museum of Denmark, University of Copenhagen, DK-1350 Copenhagen, Denmark
| | - Morten T Limborg
- National History Museum of Denmark, University of Copenhagen, DK-1350 Copenhagen, Denmark.
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