Effective translation of rare disease diagnosis knowledge into therapeutic applications is achievable within a reasonable timeframe; where mutations are amenable to current antisense oligonucleotide technology. In our study, we identified five distinct types of abnormal splice-causing mutations in patients with rare genetic disorders and developed a tailored antisense oligonucleotide for each mutation type using phosphorodiamidate morpholino oligomers with or without octa-guanidine dendrimers and 2'-O-methoxyethyl phosphorothioate. We observed variations in treatment effects and efficiencies, influenced by both the chosen chemistry and the specific nature of the aberrant splicing patterns targeted for correction. Our study demonstrated the successful correction of all five different types of aberrant splicing. Our findings reveal that effective correction of aberrant splicing can depend on altering the chemical composition of oligonucleotides and suggest a fast, efficient, and feasible approach for developing personalized therapeutic interventions for genetic disorders within short time frames.

• MeSH
• Oligonucleotides, Antisense * therapeutic use   genetics   MeSH
• Genetic Diseases, Inborn genetics   therapy   MeSH
• Humans MeSH
• Morpholinos therapeutic use   genetics   MeSH
• Mutation * MeSH
• RNA Splicing * MeSH
• Rare Diseases * genetics   drug therapy   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH

Use of blood RNA sequencing (RNA-seq) as a splicing analysis tool for clinical interpretation of variants of uncertain significance (VUSs) found via whole-genome and exome sequencing can be difficult for genes that have low expression in the blood due to insufficient read count coverage aligned to specific genes of interest. Here, we present a short amplicon reverse transcription-polymerase chain reaction(RT-PCR) for the detection of genes with low blood expression. Short amplicon RT-PCR, is designed to span three exons where an exon harboring a variant is flanked by one upstream and one downstream exon. We tested short amplicon RT-PCRs for genes that have median transcripts per million (TPM) values less than one according to the genotype-tissue expression database. Median TPM values of genes analyzed in this study are SYN1 = 0.8549, COL1A1 = 0.6275, TCF4 = 0.4009, DSP = .2894, TTN = 0.2851, COL5A2 = 0.1036, TERT = 0.04452, NTRK2 = 0.0344, ABCA4 = 0.00744, PRPH = 0, and WT1 = 0. All these genes show insufficient exon-spanning read coverage in our RNA-seq data to allow splicing analysis. We successfully detected all genes tested except PRPH and WT1. Aberrant splicing was detected in SYN1, TCF4, NTRK2, TTN, and TERT VUSs. Therefore, our results show short amplicon RT-PCR is a useful alternative for the analysis of splicing events in genes with low TPM in blood RNA for clinical diagnostics.

• MeSH
• ATP-Binding Cassette Transporters genetics   MeSH
• Alternative Splicing * MeSH
• Humans MeSH
• Reverse Transcriptase Polymerase Chain Reaction MeSH
• Reverse Transcription MeSH
• RNA * genetics   MeSH
• RNA Splicing genetics   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Alternative pre-mRNA splicing is a fundamental post-transcriptional regulatory mechanism. Cancer-specific misregulation of the splicing process may lead to formation of irregular alternative splicing variants (ASVs) with a potentially negative impact on cellular homeostasis. Alternative splicing of BRCA1 pre-mRNA can give rise to BRCA1 protein isoforms that possess dramatically altered biological activities compared with full-length wild-type BRCA1. During the screening of high-risk breast cancer (BC) families we ascertained numerous BRCA1 ASVs, however, their clinical significance for BC development is largely unknown. In this study, we examined the influence of the BRCA1Δ17-19 ASV, which lacks a portion of the BRCT domain, on DNA repair capacity using human MCF-7 BC cell clones with stably modified BRCA1 expression. Our results show that overexpression of BRCA1Δ17-19 impairs homologous recombination repair (sensitizes cells to mitomycin C), delays repair of ionizing radiation-induced DNA damage and dynamics of the ionizing radiation-induced foci (IRIF) formation, and undermines also the non-homologous end joining repair (NHEJ) activity. Mechanistically, BRCA1Δ17-19 cannot interact with the partner proteins Abraxas and CtIP, thus preventing interactions known to be critical for processing of DNA lesions. We propose that the observed inability of BRCA1Δ17-19 to functionally replace wtBRCA1 in repair of DNA double-strand breaks (DDSB) reflects impaired capacity to form the BRCA1-A and -C repair complexes. Our findings indicate that expression of BRCA1Δ17-19 may negatively influence genome stability by reducing the DDSB repair velocity, thereby contributing to enhanced probability of cancer development in the affected families.

• MeSH
• Alternative Splicing MeSH
• Radiation, Ionizing MeSH
• Nuclear Proteins metabolism   MeSH
• Humans MeSH
• MCF-7 Cells MeSH
• DNA Repair * MeSH
• DNA Damage radiation effects   MeSH
• BRCA1 Protein genetics   metabolism   MeSH
• Protein Structure, Tertiary MeSH
• Carrier Proteins metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Alternative pre-mRNA splicing increases transcriptome plasticity by forming naturally-occurring alternative splicing variants (ASVs). Alterations of splicing processes, caused by DNA mutations, result in aberrant splicing and the formation of aberrant mRNA isoforms. Analyses of hereditary cancer predisposition genes reveal many DNA variants with unknown clinical significance (VUS) that potentially affect pre-mRNA splicing. Therefore, a comprehensive description of ASVs is an essential prerequisite for the interpretation of germline VUS in high-risk individuals. To identify ASVs in a gene of interest, we have proposed an approach based on multiplex PCR (mPCR) amplification of all theoretically possible exon-exon junctions and subsequent characterization of size-selected and pooled mPCR products by next-generation sequencing (NGS). The efficiency of this method is illustrated by a comprehensive analysis of BRCA1 ASVs in human leukocytes, normal mammary, and adipose tissues and stable cell lines. We revealed 94 BRCA1 ASVs, including 29 variants present in all tested samples. While differences in the qualitative expression of BRCA1 ASVs among the analyzed human tissues were minor, larger differences were detected between tissue and cell line samples. Compared with other ASV analysis methods, this approach represents a highly sensitive and rapid alternative for the identification of ASVs in any gene of interest.

• MeSH
• Alternative Splicing * MeSH
• RNA Isoforms MeSH
• Humans MeSH
• Multiplex Polymerase Chain Reaction methods   MeSH
• Mutation * MeSH
• Breast Neoplasms genetics   MeSH
• BRCA1 Protein genetics   MeSH
• Computational Biology MeSH
• High-Throughput Nucleotide Sequencing methods   MeSH
• Check Tag
• Humans MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

Splicing-affecting mutations can disrupt gene function by altering the transcript assembly. To ascertain splicing dysregulation principles, we modified a minigene assay for the parallel high-throughput evaluation of different mutations by next-generation sequencing. In our model system, all exonic and six intronic positions of the SMN1 gene's exon 7 were mutated to all possible nucleotide variants, which amounted to 180 unique single-nucleotide mutants and 470 double mutants. The mutations resulted in a wide range of splicing aberrations. Exonic splicing-affecting mutations resulted either in substantial exon skipping, supposedly driven by predicted exonic splicing silencer or cryptic donor splice site (5'ss) and de novo 5'ss strengthening and use. On the other hand, a single disruption of exonic splicing enhancer was not sufficient to cause major exon skipping, suggesting these elements can be substituted during exon recognition. While disrupting the acceptor splice site led only to exon skipping, some 5'ss mutations potentiated the use of three different cryptic 5'ss. Generally, single mutations supporting cryptic 5'ss use displayed better pre-mRNA/U1 snRNA duplex stability and increased splicing regulatory element strength across the original 5'ss. Analyzing double mutants supported the predominating splicing regulatory elements' effect, but U1 snRNA binding could contribute to the global balance of splicing isoforms. Based on these findings, we suggest that creating a new splicing enhancer across the mutated 5'ss can be one of the main factors driving cryptic 5'ss use.

• MeSH
• Alternative Splicing * MeSH
• Cell Line MeSH
• Exons * MeSH
• Nucleic Acid Conformation MeSH
• Humans MeSH
• RNA Splice Sites MeSH
• Mutation * MeSH
• Mutagenesis MeSH
• Survival of Motor Neuron 1 Protein chemistry   genetics   metabolism   MeSH
• RNA, Small Nuclear chemistry   genetics   metabolism   MeSH
• Molecular Dynamics Simulation MeSH
• Protein Binding MeSH
• Computational Biology methods   MeSH
• High-Throughput Nucleotide Sequencing MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Familial adenomatous polyposis (FAP) is an autosomal dominant syndrome with almost 100 % risk of colorectal cancer. The typical FAP is characterized by hundreds to thousands of colorectal adenomatous polyps and by extracolonic manifestations, later onset and lower number of polyps in colon is characteristic of an attenuated form (AFAP). We analyzed the APC gene for germline mutations in 90 FAP/AFAP patients. Mutation screening was performed using Denaturing Gradient Gel Electrophoresis. DNA fragments showing an aberrant electrophoretic banding pattern were sequenced. APC-mutation-negative probands were screened for large deletions of the APC gene using multiplex ligation dependent probe amplification. Analysis of mRNA variants followed in probands with possible splicing mutation by PCR amplification of target site flanking exons and sequencing the normal and aberrant products. We identified 30 germline variants among 36 unrelated probands including large deletions. Eleven APC variants detected last two years have not been reported yet. At all, fifteen of them are expected to cause errors in mRNA splicing. Analysis of mRNA in ten of these patients revealed exon skipping in seven cases, exonisation of intron in one of these as well, change of the amount of alternatively spliced product in one case, and no effect was found in three cases. In two of the patients, the biopsy of colon mucosa and polyp enabled us to examine the effect of the mutation on splicing pattern in colon cells directly. The comparison of alternative and standard transcript amount showed similar transcription pattern of exon 14 in control colon mucosa tissue (9 samples) as in 51 blood control samples.

• MeSH
• Alternative Splicing * MeSH
• Adenomatous Polyposis Coli genetics   MeSH
• Genetic Predisposition to Disease MeSH
• Genes, APC * MeSH
• Colorectal Neoplasms genetics   MeSH
• Humans MeSH
• Mutation MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic MeSH

Significant proportion of human diseases is genetically determined and successful treatment is dependent on precise diagnosis of causal mutations. However, their identification is not always so unambiguous, although relevant sequence data is available. Modern genomic methods are able to uncover a considerable number of sequence variants with unknown impact on disease. Sequence variants frequently influence the gene expression through alteration of pre-mRNA splicing, but this effect can be hidden, if the splicing regulatory function of mutated regions was not proven in advance. The identification of splicing regulatory elements (SREs) is therefore a crucial step in evaluation of each mutation as potentially pathogenic. The aim of the project is to localize functional SREs and to try to define some rules for their occurrence by performing a systematic experimental analysis of ten regions in genes involved in disease development. Acquired „hot spot“ map of splicing affecting regions should act as an additional tool for diagnostics of aberrant splicing in newly identified gene variants.

Značná část lidských chorob má genetickou příčinu a pro úspěšnou léčbu je často nezbytné přesně určit, která mutace chorobu způsobuje. Identifikace kauzálních mutací však není vždy jednoznačná, a to i tehdy, máme-li k dispozici relevantní sekvence DNA. Moderní celogenomové metody odhalí řadu sekvenčních variant, u kterých není příčinná souvislost s chorobou zřejmá. Mnohé varianty ovlivňují genovou expresi změnou sestřihu pre-mRNA, ale tento efekt nemusí být odhalen, pokud nebylo již dříve prokázáno, že daná oblast obsahuje regulační elementy sestřihu (SRE). Jejich identifikace je proto klíčovým faktorem pro vyhodnocení vlivu takových mutací na vznik choroby. Projekt si klade za cíl lokalizovat funkční SRE a pokusit se nalézt obecná pravidla jejich výskytu v cílových sekvencích. Proto bude provedena systematická experimentální analýza vybraných oblastí genů, které jsou zodpovědné za vznik závažných lidských chorob. Získaná mapa míst náchylných k mutacím vyvolávajícím změny sestřihu bude využita jako pomocný nástroj pro diagnostiku aberantního sestřihu u nově identifikovaných mutací.

• MeSH
• Genetic Predisposition to Disease MeSH
• Genetic Diseases, Inborn genetics   MeSH
• Humans MeSH
• Mutation genetics   MeSH
• RNA Splicing genetics   MeSH
• Check Tag
• Humans MeSH

• Conspectus
• Patologie. Klinická medicína
• NML Fields
• genetika, lékařská genetika
• NML Publication type
• závěrečné zprávy o řešení grantu AZV MZ ČR

Novel drug discoveries have shifted the treatment paradigms of most hematological malignancies, including multiple myeloma (MM). However, this plasma cell malignancy remains incurable, and novel therapies are therefore urgently needed. Whole-genome transcriptome analyses in a large cohort of MM patients demonstrated that alterations in pre-mRNA splicing (AS) are frequent in MM. This manuscript describes approaches to identify disease-specific alterations in MM and proposes RNA-based therapeutic strategies to eradicate such alterations. As a "proof of concept", we examined the causes of aberrant HMMR (Hyaluronan-mediated motility receptor) splicing in MM. We identified clusters of single nucleotide variations (SNVs) in the HMMR transcript where the altered splicing took place. Using bioinformatics tools, we predicted SNVs and splicing factors that potentially contribute to aberrant HMMR splicing. Based on bioinformatic analyses and validation studies, we provided the rationale for RNA-based therapeutic strategies to selectively inhibit altered HMMR splicing in MM. Since splicing is a hallmark of many cancers, strategies described herein for target identification and the design of RNA-based therapeutics that inhibit gene splicing can be applied not only to other genes in MM but also more broadly to other hematological malignancies and solid tumors as well.

• MeSH
• Alternative Splicing MeSH
• Hematologic Neoplasms * MeSH
• Humans MeSH
• Multiple Myeloma * genetics   therapy   MeSH
• RNA MeSH
• RNA Splicing MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Research Support, N.I.H., Extramural MeSH

• MeSH
• Chromosome Aberrations * MeSH
• Humans MeSH
• DNA Damage MeSH
• Reference Values MeSH
• RNA Splicing * MeSH
• Check Tag
• Humans MeSH
• Publication type
• Letter MeSH

Purpose: To report molecular genetic findings in six probands with congenital hereditary endothelial dystrophy (CHED) variably associated with hearing loss (also known as Harboyan syndrome). Furthermore, we developed a cellular model to determine if disease-associated variants induce aberrant SLC4A11 pre-mRNA splicing. Methods: Direct sequencing of the entire SLC4A11 coding region was performed in five probands. In one individual, whole genome sequencing was undertaken. The effect of c.2240+5G>A on pre-mRNA splicing was evaluated in a corneal endothelial-like (CE-like) cell model expressing SLC4A11. CE-like cells were derived from autologous induced pluripotent stem cells (iPSCs) via neural crest cells exposed to B27, PDGF-BB, and DKK-2. Total RNA was extracted, and RT-PCR was performed followed by Sanger and a targeted next generation sequencing (NGS) approach to identify and quantify the relative abundance of alternatively spliced transcripts. Results: In total, 11 different mutations in SLC4A11 evaluated as pathogenic were identified; of these, c.1237G>A, c.2003T>C, c.1216+1G>A, and c.2240+5G>A were novel. The c.2240+5G>A variant was demonstrated to result in aberrant pre-mRNA splicing. A targeted NGS approach confirmed that the variant introduces a leaky cryptic splice donor site leading to the production of a transcript containing an insertion of six base pairs with the subsequent introduction of a premature stop codon (p.Thr747*). Furthermore, a subset of transcripts comprising full retention of intron 16 also were observed, leading to the same functionally null allele. Conclusions: This proof-of-concept study highlights the potential of using CE-like cells to investigate the pathogenic consequences of SLC4A11 disease-associated variants.

• MeSH
• Antiporters biosynthesis   genetics   MeSH
• Cell Differentiation MeSH
• Corneal Dystrophies, Hereditary genetics   metabolism   pathology   MeSH
• Child MeSH
• Adult MeSH
• Induced Pluripotent Stem Cells cytology   metabolism   MeSH
• Cells, Cultured MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Hearing Loss, Sensorineural genetics   metabolism   pathology   MeSH
• Child, Preschool MeSH
• RNA Precursors MeSH
• Anion Transport Proteins biosynthesis   genetics   MeSH
• Gene Expression Regulation * MeSH
• RNA genetics   MeSH
• Pedigree MeSH
• Endothelium, Corneal metabolism   pathology   MeSH
• Aged MeSH
• RNA Splicing MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Adolescent MeSH
• Young Adult MeSH
• Male MeSH
• Child, Preschool MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH