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A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments

Fragile X syndrome (FXS) is caused by silencing of the FMR1 gene, which encodes a protein with a critical role in synaptic plasticity. The molecular abnormality underlying FMR1 silencing, CGG repeat expansion, is well characterized; however, delineation of the pathway from DNA to RNA to protein usin...

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Autores principales: Budimirovic, Dejan B., Schlageter, Annette, Filipovic-Sadic, Stela, Protic, Dragana D., Bram, Eran, Mahone, E. Mark, Nicholson, Kimberly, Culp, Kristen, Javanmardi, Kamyab, Kemppainen, Jon, Hadd, Andrew, Sharp, Kevin, Adayev, Tatyana, LaFauci, Giuseppe, Dobkin, Carl, Zhou, Lili, Brown, William Ted, Berry-Kravis, Elizabeth, Kaufmann, Walter E., Latham, Gary J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7601415/
https://www.ncbi.nlm.nih.gov/pubmed/33008014
http://dx.doi.org/10.3390/brainsci10100694
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author Budimirovic, Dejan B.
Schlageter, Annette
Filipovic-Sadic, Stela
Protic, Dragana D.
Bram, Eran
Mahone, E. Mark
Nicholson, Kimberly
Culp, Kristen
Javanmardi, Kamyab
Kemppainen, Jon
Hadd, Andrew
Sharp, Kevin
Adayev, Tatyana
LaFauci, Giuseppe
Dobkin, Carl
Zhou, Lili
Brown, William Ted
Berry-Kravis, Elizabeth
Kaufmann, Walter E.
Latham, Gary J.
author_facet Budimirovic, Dejan B.
Schlageter, Annette
Filipovic-Sadic, Stela
Protic, Dragana D.
Bram, Eran
Mahone, E. Mark
Nicholson, Kimberly
Culp, Kristen
Javanmardi, Kamyab
Kemppainen, Jon
Hadd, Andrew
Sharp, Kevin
Adayev, Tatyana
LaFauci, Giuseppe
Dobkin, Carl
Zhou, Lili
Brown, William Ted
Berry-Kravis, Elizabeth
Kaufmann, Walter E.
Latham, Gary J.
author_sort Budimirovic, Dejan B.
collection PubMed
description Fragile X syndrome (FXS) is caused by silencing of the FMR1 gene, which encodes a protein with a critical role in synaptic plasticity. The molecular abnormality underlying FMR1 silencing, CGG repeat expansion, is well characterized; however, delineation of the pathway from DNA to RNA to protein using biosamples from well characterized patients with FXS is limited. Since FXS is a common and prototypical genetic disorder associated with intellectual disability (ID) and autism spectrum disorder (ASD), a comprehensive assessment of the FMR1 DNA-RNA-protein pathway and its correlations with the neurobehavioral phenotype is a priority. We applied nine sensitive and quantitative assays evaluating FMR1 DNA, RNA, and FMRP parameters to a reference set of cell lines representing the range of FMR1 expansions. We then used the most informative of these assays on blood and buccal specimens from cohorts of patients with different FMR1 expansions, with emphasis on those with FXS (N = 42 total, N = 31 with FMRP measurements). The group with FMRP data was also evaluated comprehensively in terms of its neurobehavioral profile, which allowed molecular–neurobehavioral correlations. FMR1 CGG repeat expansions, methylation levels, and FMRP levels, in both cell lines and blood samples, were consistent with findings of previous FMR1 genomic and protein studies. They also demonstrated a high level of agreement between blood and buccal specimens. These assays further corroborated previous reports of the relatively high prevalence of methylation mosaicism (slightly over 50% of the samples). Molecular-neurobehavioral correlations confirmed the inverse relationship between overall severity of the FXS phenotype and decrease in FMRP levels (N = 26 males, mean 4.2 ± 3.3 pg FMRP/ng genomic DNA). Other intriguing findings included a significant relationship between the diagnosis of FXS with ASD and two-fold lower levels of FMRP (mean 2.8 ± 1.3 pg FMRP/ng genomic DNA, p = 0.04), in particular observed in younger age- and IQ-adjusted males (mean age 6.9 ± 0.9 years with mean 3.2 ± 1.2 pg FMRP/ng genomic DNA, 57% with severe ASD), compared to FXS without ASD. Those with severe ID had even lower FMRP levels independent of ASD status in the male-only subset. The results underscore the link between FMR1 expansion, gene methylation, and FMRP deficit. The association between FMRP deficiency and overall severity of the neurobehavioral phenotype invites follow up studies in larger patient cohorts. They would be valuable to confirm and potentially extend our initial findings of the relationship between ASD and other neurobehavioral features and the magnitude of FMRP deficit. Molecular profiling of individuals with FXS may have important implications in research and clinical practice.
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spelling pubmed-76014152020-11-01 A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments Budimirovic, Dejan B. Schlageter, Annette Filipovic-Sadic, Stela Protic, Dragana D. Bram, Eran Mahone, E. Mark Nicholson, Kimberly Culp, Kristen Javanmardi, Kamyab Kemppainen, Jon Hadd, Andrew Sharp, Kevin Adayev, Tatyana LaFauci, Giuseppe Dobkin, Carl Zhou, Lili Brown, William Ted Berry-Kravis, Elizabeth Kaufmann, Walter E. Latham, Gary J. Brain Sci Article Fragile X syndrome (FXS) is caused by silencing of the FMR1 gene, which encodes a protein with a critical role in synaptic plasticity. The molecular abnormality underlying FMR1 silencing, CGG repeat expansion, is well characterized; however, delineation of the pathway from DNA to RNA to protein using biosamples from well characterized patients with FXS is limited. Since FXS is a common and prototypical genetic disorder associated with intellectual disability (ID) and autism spectrum disorder (ASD), a comprehensive assessment of the FMR1 DNA-RNA-protein pathway and its correlations with the neurobehavioral phenotype is a priority. We applied nine sensitive and quantitative assays evaluating FMR1 DNA, RNA, and FMRP parameters to a reference set of cell lines representing the range of FMR1 expansions. We then used the most informative of these assays on blood and buccal specimens from cohorts of patients with different FMR1 expansions, with emphasis on those with FXS (N = 42 total, N = 31 with FMRP measurements). The group with FMRP data was also evaluated comprehensively in terms of its neurobehavioral profile, which allowed molecular–neurobehavioral correlations. FMR1 CGG repeat expansions, methylation levels, and FMRP levels, in both cell lines and blood samples, were consistent with findings of previous FMR1 genomic and protein studies. They also demonstrated a high level of agreement between blood and buccal specimens. These assays further corroborated previous reports of the relatively high prevalence of methylation mosaicism (slightly over 50% of the samples). Molecular-neurobehavioral correlations confirmed the inverse relationship between overall severity of the FXS phenotype and decrease in FMRP levels (N = 26 males, mean 4.2 ± 3.3 pg FMRP/ng genomic DNA). Other intriguing findings included a significant relationship between the diagnosis of FXS with ASD and two-fold lower levels of FMRP (mean 2.8 ± 1.3 pg FMRP/ng genomic DNA, p = 0.04), in particular observed in younger age- and IQ-adjusted males (mean age 6.9 ± 0.9 years with mean 3.2 ± 1.2 pg FMRP/ng genomic DNA, 57% with severe ASD), compared to FXS without ASD. Those with severe ID had even lower FMRP levels independent of ASD status in the male-only subset. The results underscore the link between FMR1 expansion, gene methylation, and FMRP deficit. The association between FMRP deficiency and overall severity of the neurobehavioral phenotype invites follow up studies in larger patient cohorts. They would be valuable to confirm and potentially extend our initial findings of the relationship between ASD and other neurobehavioral features and the magnitude of FMRP deficit. Molecular profiling of individuals with FXS may have important implications in research and clinical practice. MDPI 2020-09-30 /pmc/articles/PMC7601415/ /pubmed/33008014 http://dx.doi.org/10.3390/brainsci10100694 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Budimirovic, Dejan B.
Schlageter, Annette
Filipovic-Sadic, Stela
Protic, Dragana D.
Bram, Eran
Mahone, E. Mark
Nicholson, Kimberly
Culp, Kristen
Javanmardi, Kamyab
Kemppainen, Jon
Hadd, Andrew
Sharp, Kevin
Adayev, Tatyana
LaFauci, Giuseppe
Dobkin, Carl
Zhou, Lili
Brown, William Ted
Berry-Kravis, Elizabeth
Kaufmann, Walter E.
Latham, Gary J.
A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments
title A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments
title_full A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments
title_fullStr A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments
title_full_unstemmed A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments
title_short A Genotype-Phenotype Study of High-Resolution FMR1 Nucleic Acid and Protein Analyses in Fragile X Patients with Neurobehavioral Assessments
title_sort genotype-phenotype study of high-resolution fmr1 nucleic acid and protein analyses in fragile x patients with neurobehavioral assessments
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7601415/
https://www.ncbi.nlm.nih.gov/pubmed/33008014
http://dx.doi.org/10.3390/brainsci10100694
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