Молекулярно-генетический анализ 617 российских пациентов с клиническим диагнозом «нейрофиброматоз»: новые патогенные и редкие непатогенные генетические варианты

Abstract

Background. In cases of neurofibromatosis type 1 and type 2, pathogenic mutations are distributed evenly along the coding regions of the NF1 and NF2 genes. Herewith, in more than 50% of cases, the disease is the result of a de novo mutation. Therefore, the search for a causative mutation is particularly time-consuming and the catalogs of pathogenic and non-pathogenic genetic variants are an indispensable assistance handbook for geneticists in their work. Objective. To determine the spectrum of genetic alterations in Russian neurofibromatosis patients and to characterize novel pathogenic mutations and rare non-pathogenic genetic variants in the NF1 and NF2 genes. Material and methods. The study was carried out on the peripheral blood lymphocyte and/or tumor tissue DNA samples from 617 patients. NGS was performed on the Ion Torrent PGM and Ion Torrent S5 sequencing machines using NF1 and NF2 AmpliSeq gene panel. Gene panel encompasses exons of the NF1 and NF2 genes, adjacent intron segments (20-70 bp), 3’UTRs, and 5’UTRs. Sanger sequencing was used to verify pathogenic genetic variants and the MLPA method was used to search for NF1 and NF2 gross deletions. Result. Complex molecular genetic diagnostics of the NF1 and NF2 alterations was accomplished for 617 patients. The NF1 and NF2 mutations were detected in 303 and 19 cases, respectively. Conclusion. We have characterized 69 novel pathogenic mutations, 68 in the NF1 gene, and 1 in the NF2 gene, as well as 68 rare non-pathogenic genetic variants. Most non-pathogenic genetic variants are represented by synonymous SNPs and nucleotide substitutions in untranslated regions, which are particularly difficult to interpret during medical-genetic counseling.