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Dysfunctional ADAM22 implicated in progressive encephalopathy with cortical atrophy and epilepsy

OBJECTIVE: To identify the molecular genetic basis of a syndrome characterized by rapidly progressing cerebral atrophy, intractable seizures, and intellectual disability. METHODS: We performed exome sequencing in the proband and whole-genome single nucleotide polymorphism genotyping (copy number var...

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Autores principales: Muona, Mikko, Fukata, Yuko, Anttonen, Anna-Kaisa, Laari, Anni, Palotie, Aarno, Pihko, Helena, Lönnqvist, Tuula, Valanne, Leena, Somer, Mirja, Fukata, Masaki, Lehesjoki, Anna-Elina
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Wolters Kluwer 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4817901/
https://www.ncbi.nlm.nih.gov/pubmed/27066583
http://dx.doi.org/10.1212/NXG.0000000000000046
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author Muona, Mikko
Fukata, Yuko
Anttonen, Anna-Kaisa
Laari, Anni
Palotie, Aarno
Pihko, Helena
Lönnqvist, Tuula
Valanne, Leena
Somer, Mirja
Fukata, Masaki
Lehesjoki, Anna-Elina
author_facet Muona, Mikko
Fukata, Yuko
Anttonen, Anna-Kaisa
Laari, Anni
Palotie, Aarno
Pihko, Helena
Lönnqvist, Tuula
Valanne, Leena
Somer, Mirja
Fukata, Masaki
Lehesjoki, Anna-Elina
author_sort Muona, Mikko
collection PubMed
description OBJECTIVE: To identify the molecular genetic basis of a syndrome characterized by rapidly progressing cerebral atrophy, intractable seizures, and intellectual disability. METHODS: We performed exome sequencing in the proband and whole-genome single nucleotide polymorphism genotyping (copy number variant analysis) in the proband-parent trio. We used heterologous expression systems to study the functional consequences of identified mutations. RESULTS: The search for potentially deleterious recessive or de novo variants yielded compound heterozygous missense (c.1202G>A, p.Cys401Tyr) and frameshift deletion (c.2396delG, p.Ser799IlefsTer96) mutations in ADAM22, which encodes a postsynaptic receptor for LGI1. The deleterious effect of the mutations was observed in cell surface binding and immunoprecipitation assays, which revealed that both mutant proteins failed to bind to LGI1. Furthermore, immunoprecipitation assays showed that the frameshift mutant ADAM22 also did not bind to the postsynaptic scaffolding protein PSD-95. CONCLUSIONS: The mutations identified abolish the LGI1-ADAM22 ligand-receptor complex and are thus a likely primary cause of the proband's epilepsy syndrome, which is characterized by unusually rapidly progressing cortical atrophy starting at 3–4 months of age. These findings are in line with the implicated role of the LGI1-ADAM22 complex as a key player in nervous system development, specifically in functional maturation of postnatal synapses. Because the frameshift mutation affects an alternatively spliced exon with highest expression in postnatal brain, the combined effect of the mutations is likely to be hypomorphic rather than complete loss of function. This is compatible with the longer survival of the patient compared to Lgi1(−/−) and Adam22(−/−) mice, which develop lethal seizures during the first postnatal weeks.
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spelling pubmed-48179012016-04-08 Dysfunctional ADAM22 implicated in progressive encephalopathy with cortical atrophy and epilepsy Muona, Mikko Fukata, Yuko Anttonen, Anna-Kaisa Laari, Anni Palotie, Aarno Pihko, Helena Lönnqvist, Tuula Valanne, Leena Somer, Mirja Fukata, Masaki Lehesjoki, Anna-Elina Neurol Genet Article OBJECTIVE: To identify the molecular genetic basis of a syndrome characterized by rapidly progressing cerebral atrophy, intractable seizures, and intellectual disability. METHODS: We performed exome sequencing in the proband and whole-genome single nucleotide polymorphism genotyping (copy number variant analysis) in the proband-parent trio. We used heterologous expression systems to study the functional consequences of identified mutations. RESULTS: The search for potentially deleterious recessive or de novo variants yielded compound heterozygous missense (c.1202G>A, p.Cys401Tyr) and frameshift deletion (c.2396delG, p.Ser799IlefsTer96) mutations in ADAM22, which encodes a postsynaptic receptor for LGI1. The deleterious effect of the mutations was observed in cell surface binding and immunoprecipitation assays, which revealed that both mutant proteins failed to bind to LGI1. Furthermore, immunoprecipitation assays showed that the frameshift mutant ADAM22 also did not bind to the postsynaptic scaffolding protein PSD-95. CONCLUSIONS: The mutations identified abolish the LGI1-ADAM22 ligand-receptor complex and are thus a likely primary cause of the proband's epilepsy syndrome, which is characterized by unusually rapidly progressing cortical atrophy starting at 3–4 months of age. These findings are in line with the implicated role of the LGI1-ADAM22 complex as a key player in nervous system development, specifically in functional maturation of postnatal synapses. Because the frameshift mutation affects an alternatively spliced exon with highest expression in postnatal brain, the combined effect of the mutations is likely to be hypomorphic rather than complete loss of function. This is compatible with the longer survival of the patient compared to Lgi1(−/−) and Adam22(−/−) mice, which develop lethal seizures during the first postnatal weeks. Wolters Kluwer 2016-01-21 /pmc/articles/PMC4817901/ /pubmed/27066583 http://dx.doi.org/10.1212/NXG.0000000000000046 Text en © 2016 American Academy of Neurology This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (CC BY) (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Article
Muona, Mikko
Fukata, Yuko
Anttonen, Anna-Kaisa
Laari, Anni
Palotie, Aarno
Pihko, Helena
Lönnqvist, Tuula
Valanne, Leena
Somer, Mirja
Fukata, Masaki
Lehesjoki, Anna-Elina
Dysfunctional ADAM22 implicated in progressive encephalopathy with cortical atrophy and epilepsy
title Dysfunctional ADAM22 implicated in progressive encephalopathy with cortical atrophy and epilepsy
title_full Dysfunctional ADAM22 implicated in progressive encephalopathy with cortical atrophy and epilepsy
title_fullStr Dysfunctional ADAM22 implicated in progressive encephalopathy with cortical atrophy and epilepsy
title_full_unstemmed Dysfunctional ADAM22 implicated in progressive encephalopathy with cortical atrophy and epilepsy
title_short Dysfunctional ADAM22 implicated in progressive encephalopathy with cortical atrophy and epilepsy
title_sort dysfunctional adam22 implicated in progressive encephalopathy with cortical atrophy and epilepsy
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4817901/
https://www.ncbi.nlm.nih.gov/pubmed/27066583
http://dx.doi.org/10.1212/NXG.0000000000000046
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