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van der Sanden B, Neveling K, Pang AWC, Shukor S, Gallagher MD, Burke SL, Kamsteeg EJ, Hastie A, Hoischen A. Optical Genome Mapping for Applications in Repeat Expansion Disorders. Curr Protoc 2024; 4:e1094. [PMID: 38966883 DOI: 10.1002/cpz1.1094] [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] [Indexed: 07/06/2024]
Abstract
Short tandem repeat (STR) expansions are associated with more than 60 genetic disorders. The size and stability of these expansions correlate with the severity and age of onset of the disease. Therefore, being able to accurately detect the absolute length of STRs is important. Current diagnostic assays include laborious lab experiments, including repeat-primed PCR and Southern blotting, that still cannot precisely determine the exact length of very long repeat expansions. Optical genome mapping (OGM) is a cost-effective and easy-to-use alternative to traditional cytogenetic techniques and allows the comprehensive detection of chromosomal aberrations and structural variants >500 bp in length, including insertions, deletions, duplications, inversions, translocations, and copy number variants. Here, we provide methodological guidance for preparing samples and performing OGM as well as running the analysis pipelines and using the specific repeat expansion workflows to determine the exact repeat length of repeat expansions expanded beyond 500 bp. Together these protocols provide all details needed to analyze the length and stability of any repeat expansion with an expected repeat size difference from the expected wild-type allele of >500 bp. © 2024 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Genomic ultra-high-molecular-weight DNA isolation, labeling, and staining Basic Protocol 2: Data generation and genome mapping using the Bionano Saphyr® System Basic Protocol 3: Manual De Novo Assembly workflow Basic Protocol 4: Local guided assembly workflow Basic Protocol 5: EnFocus Fragile X workflow Basic Protocol 6: Molecule distance script workflow.
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Affiliation(s)
- Bart van der Sanden
- Department of Human Genetics, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Kornelia Neveling
- Department of Human Genetics, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, the Netherlands
| | | | - Syukri Shukor
- Bionano Genomics Clinical and Scientific Affairs, San Diego, California
| | | | - Stephanie L Burke
- Bionano Genomics Clinical and Scientific Affairs, San Diego, California
| | - Erik-Jan Kamsteeg
- Department of Human Genetics, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Alex Hastie
- Bionano Genomics Clinical and Scientific Affairs, San Diego, California
| | - Alexander Hoischen
- Department of Human Genetics, Research Institute for Medical Innovation, Radboud University Medical Center, Nijmegen, the Netherlands
- Department of Internal Medicine, Radboud Expertise Center for Immunodeficiency and Autoinflammation and Radboud Center for Infectious Disease (RCI), Radboud University Medical Center, Nijmegen, the Netherlands
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Jiang J, Cai X, Qu H, Yao Q, He T, Yang M, Zhou H, Zhang X. Case report: Identification of facioscapulohumeral muscular dystrophy 1 in two siblings with normal phenotypic parents using optical genome mapping. Front Neurol 2024; 15:1258831. [PMID: 38361638 PMCID: PMC10867183 DOI: 10.3389/fneur.2024.1258831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 01/05/2024] [Indexed: 02/17/2024] Open
Abstract
Objective Facioscapulohumeral muscular dystrophy type 1 (FSHD1) is one of the most common forms of autosomal-dominant muscular dystrophies characterized by variable disease penetrance due to shortened D4Z4 repeat units on 4q35. The molecular diagnosis of FSHD1 is usually made by Southern blotting, which is complex, time-consuming, and lacks clinical practicality. Therefore, in this study, optical genome mapping (OGM) is employed for the genetic diagnosis of FSHD1. Furthermore, epigenetic heterogeneity is determined from methylation analysis. Methods Genomic DNA samples from four members of the same family were subjected to whole-exome sequencing. OGM was used to identify structural variations in D4Z4, while sodium bisulfite sequencing helped identify the methylation levels of CpG sites in a region located distally to the D4Z4 array. A multidisciplinary team collected the clinical data, and comprehensive family analyses aided in the assessment of phenotypes and genotypes. Results Whole-exome sequencing did not reveal variants related to clinical phenotypes in the patients. OGM showed that the proband was a compound heterozygote for the 4qA allele with four and eight D4Z4 repeat units, whereas the affected younger brother had only one 4qA allele with four D4Z4 repeat units. Both the proband and her younger brother were found to display asymmetric weakness predominantly involving the facial, shoulder girdle, and upper arm muscles, whereas the younger brother had more severe clinical symptoms. The proband's father, who was found to be normal after a neurological examination, also carried the 4qA allele with eight D4Z4 repeat units. The unaffected mother exhibited 49 D4Z4 repeat units of the 4qA allele and a minor mosaic pattern with four D4Z4 repeat units of the 4qA allele. Consequently, the presence of the 4qA allele in the four D4Z4 repeat units strongly pointed to the occurrence of maternal germline mosaicism. The CpG6 methylation levels were lower in symptomatic patients compared to those in the asymptomatic parents. The older sister had lower clinical scores and ACSS and higher CpG6 methylation levels than that of her younger brother. Conclusions In this study, two siblings with FSHD1 with phenotypically normal parents were identified by OGM. Our findings suggest that the 4qA allele of four D4Z4 repeats was inherited through maternal germline mosaicism. The clinical phenotype heterogeneity is influenced by the CpG6 methylation levels. The results of this study greatly aid in the molecular diagnosis of FSHD1 and in also understanding the clinical phenotypic variability underlying the disease.
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Affiliation(s)
- Jieni Jiang
- Department of Medical Genetics and Prenatal Diagnosis Center, West China Second University Hospital, Sichuan University, Chengdu, China
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Xiaotang Cai
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
- Department of Rehabilitation, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Haibo Qu
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
- Department of Radiology, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Qiang Yao
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Tiantian He
- Department of Medical Genetics and Prenatal Diagnosis Center, West China Second University Hospital, Sichuan University, Chengdu, China
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Mei Yang
- Department of Medical Genetics and Prenatal Diagnosis Center, West China Second University Hospital, Sichuan University, Chengdu, China
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
| | - Hui Zhou
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
- Department of Rehabilitation, West China Second University Hospital, Sichuan University, Chengdu, China
| | - Xuemei Zhang
- Department of Medical Genetics and Prenatal Diagnosis Center, West China Second University Hospital, Sichuan University, Chengdu, China
- Department of Obstetrics and Gynecology, West China Second University Hospital, Sichuan University, Chengdu, China
- Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, Chengdu, China
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Guruju NM, Jump V, Lemmers R, Van Der Maarel S, Liu R, Nallamilli BR, Shenoy S, Chaubey A, Koppikar P, Rose R, Khadilkar S, Hegde M. Molecular Diagnosis of Facioscapulohumeral Muscular Dystrophy in Patients Clinically Suspected of FSHD Using Optical Genome Mapping. Neurol Genet 2023; 9:e200107. [PMID: 38021397 PMCID: PMC10664978 DOI: 10.1212/nxg.0000000000200107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 09/18/2023] [Indexed: 12/01/2023]
Abstract
Background and Objectives Facioscapulohumeral muscular dystrophy (FSHD) represents the third most common muscular dystrophy in the general population and is characterized by progressive and often asymmetric muscle weakness of the face, upper extremities, arms, lower leg, and hip girdle. In FSHD type 1, contraction of the number of D4Z4 repeats to 1-10 on the chromosome 4-permissive allele (4qA) results in abnormal epigenetic derepression of the DUX4 gene in skeletal muscle. In FSHD type 2, epigenetic derepression of the DUX4 gene on the permissive allele (4qA) with normal-sized D4Z4 repeats (mostly 8-20) is caused by heterozygous pathogenic variants in chromatin modifier genes such as SMCHD1, DNMT3B, or LRIF1. We present validation of the optical genome mapping (OGM) platform for accurate mapping of the D4Z4 repeat size, followed by diagnostic testing of 547 cases with a suspected clinical diagnosis of FSHD and next-generation sequencing (NGS) of the SMCHD1 gene to identify cases with FSHD2. Methods OGM with Bionano Genomics Saphyr and EnFocus FSHD analysis software was used to identify FSHD haplotypes and D4Z4 repeat number and compared with the gold standard of Southern blot-based diagnosis. A custom Agilent SureSelect enrichment kit was used to enrich SMCHD1, followed by NGS on an Illumina system with 100-bp paired-end reads. Copy number variants were assessed using NxClinical software. Results We performed OGM for the diagnosis of FSHD in 547 patients suspected of FSHD between December 2019 and December 2022, including 301 male (55%) and 246 female patients (45%). Overall, 308 of the referred patients were positive for D4Z4 contraction on a permissive haplotype, resulting in a diagnosis of FSHD1. A total of 252 of 547 patients were referred for concurrent testing for FSHD1 and FSHD2. This resulted in the identification of FSHD2 in 9/252 (3.6%) patients. In our FSHD2 cohort, the 4qA allele size ranged from 8 to 18 repeats. Among FSHD1-positive cases, 2 patients had biallelic contraction and 4 patients had homozygous contraction and showed early onset of clinical features. Nine of the 308 patients (3%) positive for 4qA contraction had mosaic 4q alleles with contraction on at least one 4qA allele. The overall diagnostic yield in our cohort was 58%. Discussion A combination of OGM to identify the FSHD haplotype and D4Z4 repeat number and NGS to identify sequence and copy number variants in the SMCHD1 gene is a practical and cost-effective option with increased precision for accurate diagnosis of FSHD types 1 and 2.
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Affiliation(s)
- Naga M Guruju
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Vanessa Jump
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Richard Lemmers
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Silvere Van Der Maarel
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Ruby Liu
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Babi R Nallamilli
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Suresh Shenoy
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Alka Chaubey
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Pratik Koppikar
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Rajiv Rose
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Satish Khadilkar
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
| | - Madhuri Hegde
- From the Revvity Omics (N.M.G., V.J., Ruby Liu, B.R.N., S.S., R.R., M.H.), Pittsburgh, PA; Leiden University Medical Centre (Richard Lemmers, S.V.D.M.), Netherlands; Bionano Genomics (A.C.), San Diego, CA; UT Dallas (P.K.), TX; Bombay Hospital (S.K.), Mumbai, India
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