1
|
Carter MT, Srour M, Au PYB, Buhas D, Dyack S, Eaton A, Inbar-Feigenberg M, Howley H, Kawamura A, Lewis SME, McCready E, Nelson TN, Vallance H. Genetic and metabolic investigations for neurodevelopmental disorders: position statement of the Canadian College of Medical Geneticists (CCMG). J Med Genet 2023; 60:523-532. [PMID: 36822643 DOI: 10.1136/jmg-2022-108962] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 01/27/2023] [Indexed: 02/25/2023]
Abstract
PURPOSE AND SCOPE The aim of this position statement is to provide recommendations for clinicians regarding the use of genetic and metabolic investigations for patients with neurodevelopmental disorders (NDDs), specifically, patients with global developmental delay (GDD), intellectual disability (ID) and/or autism spectrum disorder (ASD). This document also provides guidance for primary care and non-genetics specialists caring for these patients while awaiting consultation with a clinical geneticist or metabolic specialist. METHODS OF STATEMENT DEVELOPMENT A multidisciplinary group reviewed existing literature and guidelines on the use of genetic and metabolic investigations for the diagnosis of NDDs and synthesised the evidence to make recommendations relevant to the Canadian context. The statement was circulated for comment to the Canadian College of Medical Geneticists (CCMG) membership-at-large and to the Canadian Pediatric Society (Mental Health and Developmental Disabilities Committee); following incorporation of feedback, it was approved by the CCMG Board of Directors on 1 September 2022. RESULTS AND CONCLUSIONS Chromosomal microarray is recommended as a first-tier test for patients with GDD, ID or ASD. Fragile X testing should also be done as a first-tier test when there are suggestive clinical features or family history. Metabolic investigations should be done if there are clinical features suggestive of an inherited metabolic disease, while the patient awaits consultation with a metabolic physician. Exome sequencing or a comprehensive gene panel is recommended as a second-tier test for patients with GDD or ID. Genetic testing is not recommended for patients with NDDs in the absence of GDD, ID or ASD, unless accompanied by clinical features suggestive of a syndromic aetiology or inherited metabolic disease.
Collapse
Affiliation(s)
| | - Myriam Srour
- Division of Neurology, McGill University Health Centre, Montreal, Québec, Canada
- Department of Pediatrics, McGill University, Montréal, QC, Canada
| | - Ping-Yee Billie Au
- Department of Medical Genetics, Alberta Children's Hospital, Calgary, Alberta, Canada
| | - Daniela Buhas
- Division of Medical Genetics, Department of Specialized Medicine, McGill University Health Centre, McGill University, Montreal, Québec, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Sarah Dyack
- Division of Medical Genetics, IWK Health Centre, Halifax, Nova Scotia, Canada
- Department of Pediatrics, Dalhousie University, Halifax, NS, Canada
| | - Alison Eaton
- Department of Medical Genetics, Stollery Children's Hospital, Edmonton, Alberta, Canada
- Department of Medical Genetics, University of Alberta, Edmonton, AB, Canada
| | - Michal Inbar-Feigenberg
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Heather Howley
- Office of Research Services, CHEO Research Institute, Ottawa, Ontario, Canada
| | - Anne Kawamura
- Division of Developmental Pediatrics, Holland Bloorview Kids Rehabilitation Hospital, Toronto, Ontario, Canada
- Department of Paediatrics, University of Toronto, Toronto, ON, Canada
- Mental Health and Developmental Disability Committee, Canadian Pediatric Society, Ottawa, ON, Canada
- Canadian Paediatric Society, Toronto, Ontario, Canada
| | - Suzanne M E Lewis
- Department of Medical Genetics, BC Children's and Women's Hospital, Vancouver, British Columbia, Canada
| | - Elizabeth McCready
- Department of Pathology and Molecular Medicine, McMaster University, McMaster University, Hamilton, ON, Canada, Hamilton, Ontario, Canada
- Hamilton Regional Laboratory Medicine Program, Hamilton Health Sciences Centre, Hamilton, ON, Canada
| | - Tanya N Nelson
- Department of Pathology and Laboratory Medicine, BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| | - Hilary Vallance
- Department of Pathology and Laboratory Medicine, BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
| |
Collapse
|
2
|
Evaluation of Individuals with Non-Syndromic Global Developmental Delay and Intellectual Disability. CHILDREN 2023; 10:children10030414. [PMID: 36979972 PMCID: PMC10047567 DOI: 10.3390/children10030414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 02/11/2023] [Accepted: 02/16/2023] [Indexed: 02/24/2023]
Abstract
Global Developmental Delay (GDD) and Intellectual Disability (ID) are two of the most common presentations encountered by physicians taking care of children. GDD/ID is classified into non-syndromic GDD/ID, where GDD/ID is the sole evident clinical feature, or syndromic GDD/ID, where there are additional clinical features or co-morbidities present. Careful evaluation of children with GDD and ID, starting with detailed history followed by a thorough examination, remain the cornerstone for etiologic diagnosis. However, when initial history and examination fail to identify a probable underlying etiology, further genetic testing is warranted. In recent years, genetic testing has been shown to be the single most important diagnostic modality for clinicians evaluating children with non-syndromic GDD/ID. In this review, we discuss different genetic testing currently available, review common underlying copy-number variants and molecular pathways, explore the recent evidence and recommendations for genetic evaluation and discuss an approach to the diagnosis and management of children with non-syndromic GDD and ID.
Collapse
|
3
|
Abstract
Neurodevelopmental disorders are the most prevalent chronic medical conditions encountered in pediatric primary care. In addition to identifying appropriate descriptive diagnoses and guiding families to evidence-based treatments and supports, comprehensive care for individuals with neurodevelopmental disorders includes a search for an underlying etiologic diagnosis, primarily through a genetic evaluation. Identification of an underlying genetic etiology can inform prognosis, clarify recurrence risk, shape clinical management, and direct patients and families to condition-specific resources and supports. Here we review the utility of genetic testing in patients with neurodevelopmental disorders and describe the three major testing modalities and their yields - chromosomal microarray, exome sequencing (with/without copy number variant calling), and FMR1 CGG repeat analysis for fragile X syndrome. Given the diagnostic yield of genetic testing and the potential for clinical and personal utility, there is consensus that genetic testing should be offered to all patients with global developmental delay, intellectual disability, and/or autism spectrum disorder. Despite this recommendation, data suggest that a minority of children with autism spectrum disorder and intellectual disability have undergone genetic testing. To address this gap in care, we describe a structured but flexible approach to facilitate integration of genetic testing into clinical practice across pediatric specialties and discuss future considerations for genetic testing in neurodevelopmental disorders to prepare pediatric providers to care for patients with such diagnoses today and tomorrow.
Collapse
Affiliation(s)
- Juliann M. Savatt
- Autism & Developmental Medicine Institute, Geisinger, Danville, PA, United States
| | | |
Collapse
|
4
|
Lubala TK, Lumaka A, Kanteng G, Mutesa L, Mukuku O, Wembonyama S, Hagerman R, Luboya ON, Lukusa Tshilobo P. Fragile X checklists: A meta-analysis and development of a simplified universal clinical checklist. Mol Genet Genomic Med 2018; 6:526-532. [PMID: 29624914 PMCID: PMC6081230 DOI: 10.1002/mgg3.398] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 03/06/2018] [Accepted: 03/06/2018] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Clinical checklists available have been developed to assess the risk of a positive Fragile X syndrome but they include relatively small sample sizes. Therefore, we carried out a meta-analysis that included statistical pooling of study results to obtain accurate figures on the prevalence of clinical predictors of Fragile X syndrome among patients with intellectual disability, thereby helping health professionals to improve their referrals for Fragile X testing. METHODS All published studies consisting of cytogenetic and/or molecular screening for fragile X syndrome among patients with intellectual disability, were eligible for the meta-analysis. All patients enrolled in clinical checklists trials of Fragile X syndrome were eligible for this review, with no exclusion based on ethnicity or age. Odds ratio values, with 95% confidence intervals as well as Cronbach coefficient alpha, was reported to assess the frequency of clinical characteristics in subjects with intellectual disability with and without the fragile X mutation to determine the most discriminating. RESULTS The following features were strongly associated with Fragile X syndrome: skin soft and velvety on the palms with redundancy of skin on the dorsum of hand [OR: 16.85 (95% CI 10.4-27.3; α:0.97)], large testes [OR: 7.14 (95% CI 5.53-9.22; α: 0.80)], large and prominent ears [OR: 18.62 (95% CI 14.38-24.1; α: 0.98)], pale blue eyes [OR: 8.97 (95% CI 4.75-16.97; α: 0.83)], family history of intellectual disability [OR: 3.43 (95% CI 2.76-4.27; α: 0.81)] as well as autistic-like behavior [OR: 3.08 (95% CI 2.48-3.83; α: 0.77)], Flat feet [OR: 11.53 (95% CI 6.79-19.56; α:0.91)], plantar crease [OR: 3.74 (95% CI 2.67-5.24; α: 0.70)]. We noted a weaker positive association between transverse palmar crease [OR: 2.68 (95% CI 1.70-4.18; α: 0.51)], elongated face [OR: 3.69 (95% CI 2.84-4.81; α: 0.63)]; hyperextensible metacarpo-phalangeal joints [OR: 2.68 (95% CI 2.15-3.34; α: 0.57)] and the Fragile X syndrome. CONCLUSION This study has identified the highest risk features for patients with Fragile X syndrome that have been used to design a universal clinical checklist.
Collapse
Affiliation(s)
- Toni Kasole Lubala
- Division of Dysmorphology & Birth DefectsDepartment of PediatricsUniversity of LubumbashiLubumbashiCongo
| | - Aimé Lumaka
- Faculté de MédecineDépartement de PédiatrieUniversité de KinshasaKinshasaCongo
- Centre de Génétique HumaineInstitut National de Recherche BiomédicaleKinshasaCongo
| | - Gray Kanteng
- Division of Dysmorphology & Birth DefectsDepartment of PediatricsUniversity of LubumbashiLubumbashiCongo
| | - Léon Mutesa
- Center for Human GeneticsSchool of Medicine and PharmacyCollege of Medicine and Health SciencesUniversity of RwandaKigaliRwanda
| | - Olivier Mukuku
- Département de PédiatrieInstitut Supérieur des Techniques MédicalesLubumbashiCongo
| | - Stanislas Wembonyama
- Division of Dysmorphology & Birth DefectsDepartment of PediatricsUniversity of LubumbashiLubumbashiCongo
| | - Randi Hagerman
- MIND InstituteUniversity of California DavisSacramentoCAUSA
- Department of PediatricsUniversity of California Davis Medical CenterSacramentoCAUSA
| | - Oscar Numbi Luboya
- Division of Dysmorphology & Birth DefectsDepartment of PediatricsUniversity of LubumbashiLubumbashiCongo
| | - Prosper Lukusa Tshilobo
- Faculté de MédecineDépartement de PédiatrieUniversité de KinshasaKinshasaCongo
- Centre de Génétique HumaineInstitut National de Recherche BiomédicaleKinshasaCongo
| |
Collapse
|
5
|
Do the data really support ordering fragile X testing as a first-tier test without clinical features? Genet Med 2017; 19:1317-1322. [PMID: 28541279 PMCID: PMC5702277 DOI: 10.1038/gim.2017.64] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 03/31/2017] [Indexed: 01/12/2023] Open
Abstract
Purpose Current guidelines recommend first-tier chromosome microarray analysis (CMA) and fragile X syndrome (FX) testing for males with isolated intellectual disabilities/learning delay (ID/LD) and autism spectrum disorders (ASDs). Methods Males in our clinic with ID/LD or ASD (310) were analyzed for positive results from CMA and/or FX testing. Results CMA detected abnormalities in 29% of males with ID/LD and only 9% of males with ASD (including variants of uncertain significance and absence of heterozygosity). When males with ID/LD were tested for FX, the detection rate was 2.5% (2 of 80). Both patients had dysmorphic features and maternal family history. No males with ASD had positive FX test results. Conclusions The detection rate of CMA in males with isolated ID/LD in this study was higher than in the literature (10–20%). CMA results for males with ASD (9%) and FX testing for males with ID/LD (2.5%) overlap with the literature (7–10% and 2%, respectively). The yield of FX testing for patients with ASD was zero, which is close to that of the literature (0.5–2%). These results suggest that FX testing as a first-tier test may not be necessary, unless other criteria suggest FX.
Collapse
|
6
|
FMR1 gene mutations in patients with fragile X syndrome and obligate carriers: 30 years of experience in Chile. Genet Res (Camb) 2016; 98:e11. [PMID: 27350105 DOI: 10.1017/s0016672316000082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Fragile X syndrome (FXS) is the most common form of inherited intellectual disability (ID) and co-morbid autism. It is caused by an amplification of the CGG repeat (>200), which is known as the full mutation, within the 5'UTR of the FMR1 gene. Expansions between 55-200 CGG repeats are termed premutation and are associated with a greater risk for fragile X-associated tremor/ataxia syndrome and fragile X-associated premature ovarian insufficiency. Intermediate alleles, also called the grey zone, include approximately 45-54 repeats and are considered borderline. Individuals with less than 45 repeats have a normal FMR1 gene. We report the occurrence of CGG expansions of the FMR1 gene in Chile among patients with ID and families with a known history of FXS. Here, we present a retrospective review conducted on 2321 cases (2202 probands and 119 relatives) referred for FXS diagnosis and cascade screening at the Institute of Nutrition and Food Technology (INTA), University of Chile. Samples were analysed using traditional cytogenetic methods and/or PCR. Southern blot was used to confirm the diagnosis. Overall frequency of FMR1 expansions observed among probands was 194 (8·8%), the average age of diagnosis was 8·8 ± 5·4 years. Of 119 family members studied, 72 (60%) were diagnosed with a CGG expansion. Our results indicated that the prevalence of CGG expansions of the FMR1 gene among probands is relatively higher than other populations. The average age of diagnosis is also higher than reference values. PCR and Southern blot represent a reliable molecular technique in the diagnosis of FXS.
Collapse
|
7
|
Gonçalves TF, dos Santos JM, Gonçalves AP, Tassone F, Mendoza-Morales G, Ribeiro MG, Kahn E, Boy R, Pimentel MMG, Santos-Rebouças CB. Finding FMR1 mosaicism in Fragile X syndrome. Expert Rev Mol Diagn 2016; 16:501-7. [PMID: 26716517 DOI: 10.1586/14737159.2016.1135739] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Almost all patients with Fragile X Syndrome (FXS) exhibit a CGG repeat expansion (full mutation) in the Fragile Mental Retardation 1 gene (FMR1). Here, the authors report five unrelated males with FXS harboring a somatic full mutation/deletion mosaicism. METHODS Mutational profiles were only elucidated by using a combination of molecular approaches (CGG-based PCR, Sanger sequencing, MS-MLPA, Southern blot and mPCR). RESULTS Four patients exhibited small deletions encompassing the CGG repeats tract and flanking regions, whereas the remaining had a larger deletion comprising at least exon 1 and part of intron 1 of FMR1 gene. The presence of a 2-3 base pairs microhomology in proximal and distal non-recurrent breakpoints without scars supports the involvement of microhomology mediated induced repair (MMBIR) mechanism in three small deletions. CONCLUSION The authors data highlights the importance of using different research methods to elucidate atypical FXS mutational profiles, which are clinically undistinguishable and may have been underestimated.
Collapse
Affiliation(s)
| | | | | | - Flora Tassone
- b Department of Biochemistry and Molecular Medicine , UC Davis School of Medicine, University of California, Davis , Sacramento , CA , USA.,c Davis MIND Institute , Sacramento , CA , USA
| | - Guadalupe Mendoza-Morales
- b Department of Biochemistry and Molecular Medicine , UC Davis School of Medicine, University of California, Davis , Sacramento , CA , USA
| | - Márcia Gonçalves Ribeiro
- d Clinical Genetics Service , IPPMG, Federal University of Rio de Janeiro , Rio de Janeiro , Brazil
| | - Evelyn Kahn
- d Clinical Genetics Service , IPPMG, Federal University of Rio de Janeiro , Rio de Janeiro , Brazil
| | - Raquel Boy
- e Pedro Ernesto University Hospital , State University of Rio de Janeiro , Rio de Janeiro , Brazil
| | | | | |
Collapse
|
8
|
Fatima T, Zaidi SAH, Sarfraz N, Perween S, Khurshid F, Imtiaz F. Frequency of FMR1 gene mutation and CGG repeat polymorphism in intellectually disabled children in Pakistan. Am J Med Genet A 2014; 164A:1151-61. [PMID: 24478267 DOI: 10.1002/ajmg.a.36423] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 12/08/2013] [Indexed: 01/11/2023]
Abstract
Fragile X syndrome is considered the most common heritable form of X-linked intellectual disability (ID). The syndrome is caused by silencing of the fragile X mental retardation 1 gene (Xq27.3) due to hypermethylation. This mutation results in absence or deficit of its protein product, the fragile X mental retardation protein (FMRP) that affects synaptic plasticity in neurons, hence leads to brain dysfunction. The syndrome is widely distributed throughout the world. This study reported for the first time the frequency of the fragile X mental retardation 1 gene mutations in intellectually disabled children in Pakistan. We recruited 333 intellectually disabled children and 250 normal children with age ranging from 5 to 18 years for this study. Genomic DNA was extracted from peripheral blood and full mutations were identified by methylation sensitive PCR using primers corresponding to modified methylated and unmethylated DNA. Southern blot was used for confirmation of the results. The frequency of fragile X syndrome with full mutation was found as 4.8%. It was 6.5% in males as opposed to 0.9% in females; 29 CGG repeats were found as the most common allele; 31.5% in the intellectually disabled and 34% in control subjects. In Pakistan intellectual disability is considered as a social stigma for the individuals and their families. Due to lack of knowledge and cultural background people make such patients and families isolated. This study will increase public awareness about the intellectual disability and importance of prenatal screening and genetic counseling for vulnerable families.
Collapse
Affiliation(s)
- Tasneem Fatima
- Department of Biological and Biomedical Sciences, Aga Khan University, Karachi, Pakistan
| | | | | | | | | | | |
Collapse
|