The description of the clinical case of Nicolaides-Baraitser syndrome caused by mutations in the SMARCA2 gene
Abstract
Purpose. The purpose of this work was to describe the clinical and genetic characteristics of the patient with Nicolaides-Baraitser syndrome, caused by the previously not described missense mutation in the SMARCA2 gene. Materials and methods. Video EEG monitoring was carried out in accordance with the international system 10-20 s. Cup electrodes, which were fixed with the help of colloidal glue, were used. Exom sequencing was carried out on an Illumina NextSeq 500 sequencer with an average coverage of at least 70-100x using a panel containing 211 genes. The pathogenicity of the detected mutation was confirmed by Senger sequencing using the DNA of the patient and his parents. Results. In the patient we observed with a previously unidentified single nucleotide substitution in the gene in the 7 exon of the SMARCA2 gene, the main clinical manifestations were characterized by a combination of moderate mental retardation, a violation of expressive speech, and not pronounced dysmorphic features of the facial features characteristic of the Nicolaides-Baraitser syndrome. However, the patient described by us did not have some phenotypic signs. A sufficiently mild phenotype can be explained by the small significance of the small helicase domain encoded by the 7 exon gene in which the nucleotide replacement occurred, for the functioning of the protein. Conclusions. Taking into account all the above, it can be concluded that the variability of the clinical picture of hereditary diseases is due to the localization of the pathogenic mutation in the gene and the functional significance of the domain whose activity it violates. Thus, the description of new clinical cases of rare syndromes caused by previously not described mutations is of great importance not only for the practicing geneticist, but also for the development of molecular genetics in general and a deeper understanding of genotype-phenotype correlations.
About the Authors
E. L. Dadali
Research Centre for Medical Genetics
Russian Federation
Russian Federation
I. A. Akimova
Research Centre for Medical Genetics
Russian Federation
Russian Federation
F. A. Konovalov
Genomed LLC
Russian Federation
Russian Federation
M. A. Ampleeva
Genomed LLC
Russian Federation
Russian Federation
O. A. Shchagina
Research Centre for Medical Genetics
Russian Federation
Russian Federation
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Review
For citations:
Dadali E.L., Akimova I.A., Konovalov F.A., Ampleeva M.A., Shchagina O.A. The description of the clinical case of Nicolaides-Baraitser syndrome caused by mutations in the SMARCA2 gene. Medical Genetics. 2017;16(7):42-46. (In Russ.)
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