scholarly journals Detection of Splicing Abnormalities and Genotype-Phenotype Correlation in X-linked Alport Syndrome

2018 ◽  
Vol 29 (8) ◽  
pp. 2244-2254 ◽  
Author(s):  
Tomoko Horinouchi ◽  
Kandai Nozu ◽  
Tomohiko Yamamura ◽  
Shogo Minamikawa ◽  
Takashi Omori ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Alport Syndrome ◽  
Stop Codon ◽  
Consensus Sequence ◽  
Point Mutations ◽  
Premature Stop Codon ◽  
Transcript Level ◽  
Phenotype Correlation ◽  
Genotype Phenotype Correlation ◽  
Splicing Patterns

BackgroundX-linked Alport syndrome (XLAS) is a progressive hereditary nephropathy caused by mutations in the COL4A5 gene. Genotype-phenotype correlation in male XLAS is relatively well established; relative to truncating mutations, nontruncating mutations exhibit milder phenotypes. However, transcript comparison between XLAS cases with splicing abnormalities that result in a premature stop codon and those with nontruncating splicing abnormalities has not been reported, mainly because transcript analysis is not routinely conducted in patients with XLAS.MethodsWe examined transcript expression for all patients with suspected splicing abnormalities who were treated at one hospital between January of 2006 and July of 2017. Additionally, we recruited 46 males from 29 families with splicing abnormalities to examine genotype-phenotype correlation in patients with truncating (n=21, from 14 families) and nontruncating (n=25, from 15 families) mutations at the transcript level.ResultsWe detected 41 XLAS families with abnormal splicing patterns and described novel XLAS atypical splicing patterns (n=14) other than exon skipping caused by point mutations in the splice consensus sequence. The median age for developing ESRD was 20 years (95% confidence interval, 14 to 23 years) among patients with truncating mutations and 29 years (95% confidence interval, 25 to 40 years) among patients with nontruncating mutations (P=0.001).ConclusionsWe report unpredictable atypical splicing in the COL4A5 gene in male patients with XLAS and reveal that renal prognosis differs significantly for patients with truncating versus nontruncating splicing abnormalities. Our results suggest that splicing modulation should be explored as a therapy for XLAS with truncating mutations.

scholarly journals Therapeutic base and prime editing of COL7A1 mutations in recessive dystrophic epidermolysis bullosa

2021 ◽  
Author(s):  
Sung-ah Hong ◽  
Song-Ee Kim ◽  
A-young Lee ◽  
Gue-ho Hwang ◽  
Jong Hoon Kim ◽  
...  
Keyword(s):  
Epidermolysis Bullosa ◽  
Ex Vivo ◽  
Stop Codon ◽  
Point Mutations ◽  
Premature Stop Codon ◽  
Loss Of Function ◽  
Dystrophic Epidermolysis Bullosa ◽  
Immunodeficient Mice ◽  
Type Vii Collagen ◽  
Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a severe skin fragility disorder caused by loss-of-function mutations in the COL7A1 gene, which encodes type VII collagen (C7), a protein that functions in skin adherence. From 36 Korean RDEB patients, we identified a total of 69 pathogenic mutations (40 variants without recurrence), including point mutations (72.5%) and insertion/deletion mutations (27.5%). We used base and prime editing to correct mutations in fibroblasts from two patients (Pat1, who carried a c.3631C>T mutation in one allele, and Pat2, who carried a c.2005C>T mutation in one allele). We applied adenine base editors (ABEs) to correct the pathogenic mutation or to bypass a premature stop codon in Pat1-derived primary fibroblasts. To expand the targeting scope, we also utilized prime editors (PEs) to correct the mutations in Pat1- and Pat2-derived fibroblasts. Ultimately, we found that both ABE- and PE-mediated correction of COL7A1 mutations restored full-length C7 expression, reversed the impaired adhesion and proliferation exhibited by the patient-derived fibroblasts, and, following transfer of edited patient-derived fibroblasts into the skin of immunodeficient mice, led to C7 deposition within the dermal-epidermal junction. These results suggest that base and prime editing could be feasible strategies for ex vivo gene editing to treat RDEB.

scholarly journals Deficiency in the A-subunit of coagulation factor XIII: two novel point mutations demonstrate different effects on transcript levels

Blood ◽  
1994 ◽  
Vol 84 (2) ◽  
pp. 517-525 ◽  
Author(s):  
H Mikkola ◽  
M Syrjala ◽  
V Rasi ◽  
E Vahtera ◽  
E Hamalainen ◽  
...  
Keyword(s):  
Factor Xiii ◽  
Solid Phase ◽  
Stop Codon ◽  
Point Mutations ◽  
Premature Stop Codon ◽  
Coagulation Factor ◽  
Mrna Levels ◽  
Coagulation Factor Xiii ◽  
Stop Mutation ◽  
A Subunit

Abstract Congenital deficiency in coagulation factor XIII is a rare autosomal recessive bleeding disorder. Although the defect was characterized over 30 years ago, little is known about the molecular basis of the disorder. Here, we show two novel point mutations in the gene of the A- subunit of factor XIII in the genetically isolated population of Finland. All eight factor XIII-deficient families identified in Finland were studied. The exons of the gene of A-subunit were amplified individually by polymerase chain reaction and subsequently screened by single-strand conformation polymorphism. Sequence analysis of the abnormally migrating fragments showed two point mutations resulting in an amino acid alteration. A C-to-T transition at Arg-661 in exon XIV created a premature stop codon. This mutation was detected in six of the eight families, thus being the major alteration causing FXIII deficiency in Finland. In two of the six families, the patients were compound heterozygotes with the Arg-661-Stop mutation in one allele and either a T-to-C point mutation in exon VI or a thus far uncharacterized mutation in the other allele. The T-to-C transition in exon VI resulted in a substitution of threonine for methionine 242. The transition was found in one family only, where it was in the heterozygote form combined with the Arg-661-Stop mutation. To evaluate the consequences of these mutations, steady-state FXIII mRNA levels were quantitated by solid-phase minisequencing. In addition to the termination of translation 70 amino acids before the initial stop codon, the Arg-661- Stop mutation causes a 10- to 30-fold reduction in FXIII mRNA levels. This is also likely to result in a low translation level in the truncated polypeptide. In contrast, Met-242-Thr mutation does not seem to affect the level of mRNA. Here, the absence of a functional and immunodetectable protein is probably caused by an altered conformation of the mutant polypeptide, resulting in early degradation of the defective protein.

scholarly journals Molecular CYP21A2 diagnosis in 480 Brazilian patients with congenital adrenal hyperplasia before newborn screening introduction

2016 ◽  
Vol 175 (2) ◽  
pp. 107-116 ◽  
Author(s):  
Daniel F de Carvalho ◽  
Mirela C Miranda ◽  
Larissa G Gomes ◽  
Guiomar Madureira ◽  
José A M Marcondes ◽  
...  
Keyword(s):  
Congenital Adrenal Hyperplasia ◽  
Founder Effect ◽  
Novel Mutation ◽  
Point Mutations ◽  
Carrier Status ◽  
Adrenal Hyperplasia ◽  
Phenotype Correlation ◽  
Specific Pcr ◽  
Genotype Phenotype Correlation ◽  
Simple Virilizing

Background Most congenital adrenal hyperplasia (CAH) patients carry CYP21A2 mutations derived from conversion events involving the pseudogene, and the remaining carry new mutations. Objective To review causal mutations and genotype–phenotype correlation in 480 Brazilian patients. Methods DNA was extracted from 158 salt-wasters (SWs), 116 simple virilizing (SV), and 206 nonclassical (NC) patients. Fourteen point mutations were screened by allele-specific PCR, large rearrangements by Southern blotting/MLPA, and sequencing was performed in those with incomplete genotype. The gene founder effect was analyzed by microsatellite studies. Patients were divided into six genotypes (Null; A: <2%; B: 3–7%; C: >20% of residual enzymatic activity (EA); D: unknown EA; E: incomplete genotype). Results Targeted methodologies defined genotype in 87.6% of classical and in 80% of NC patients and the addition of sequencing in 100 and 83.5%, respectively. The most frequent mutations were p.V281L (26.6% of alleles), IVS2-13A/C>G (21.1%), and p.I172N (7.5%); seven rare mutations and one novel mutation (p.E351V) were identified. Gene founder effect was observed in all but one (p.W19X) mutation. Null, A, B, and C genotypes correlated with SW (88%), SW (70%), SV (98%), and NC forms (100%), respectively. In group D, the p.E351V mutation correlated with classical form and group E comprised exclusively NC-patients. ACTH-stimulated 17OHP level of 44.3ng/mL was the best cutoff to identify NC-patients carrying severe mutations. Conclusions We identified a good genotype–phenotype correlation in CAH, providing useful data regarding prediction of disease’s severity; moreover, we suggest that ACTH-stimulated 17OHP levels could predict carrier status for severe mutations. Sequencing is essential to optimize molecular diagnosis in Brazilian CAH patients.

scholarly journals Genotype-Phenotype Correlation in Patients with Congenital Adrenal Hyperplasia due to 21-Hydroxylase Deficiency in Cuba

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
Tania Mayvel Espinosa Reyes ◽  
Teresa Collazo Mesa ◽  
Paulina Arasely Lantigua Cruz ◽  
Adriana Agramonte Machado ◽  
Emma Domínguez Alonso ◽  
...  
Keyword(s):  
Congenital Adrenal Hyperplasia ◽  
Point Mutations ◽  
Clinical Manifestations ◽  
Adrenal Hyperplasia ◽  
Phenotype Correlation ◽  
Hydroxylase Deficiency ◽  
Cyp21a2 Gene ◽  
Genotype Phenotype Correlation ◽  
21 Hydroxylase Deficiency ◽  
Cuban Population

Background. There are several studies that show a good genotype-phenotype correlation in congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21OHD). However, there is well-documented evidence of inconsistency in some cases. Objectives. To determine if there is a correlation between the identified mutations and the clinical manifestations of 21OHD in the Cuban population. Methods. A cross-sectional descriptive study of all patients referred for a molecular diagnosis of 21OHD in Cuba from January 2000 to December 2018. The clinical manifestations of each patient were identified and classified according to the phenotype. The CYP21A2 gene was analyzed for the presence of 5 point mutations involved in the pathogenesis of 21OHD (intron 2, deletion of 8bp, I172N, P30L, and Q318X); correlation was sought between the phenotypic characteristics and the frequencies of point mutations in the patients using the Spearman test. Results. A total of 55 patients underwent direct analysis of the CYP21A2 gene in order to determine the presence of the 5 point mutations. Point mutations were identified in 31 patients, which corresponded to 56%. A statistically significant genotype-phenotype correlation was found. Conclusions. The correlation between the detected molecular defect and the clinical expression of 21OHD was reasonable in the Cuban population, which could allow phenotypic predictions to be made from the genotype.

scholarly journals In vivoRNA targeting of point mutations via suppressor tRNAs and adenosine deaminases

2017 ◽  
Author(s):  
Dhruva Katrekar ◽  
Prashant Mali
Keyword(s):  
Mouse Model ◽  
Rna Editing ◽  
Unnatural Amino Acids ◽  
Stop Codon ◽  
Genetic Diseases ◽  
Point Mutations ◽  
Premature Stop Codon ◽  
Dystrophin Gene ◽  
Multiple Challenges

ABSTRACTPoint mutations underlie many genetic diseases. In this regard, while programmable DNA nucleases have been used to repair mutations, their use for gene therapy poses multiple challenges: one, efficiency of homologous recombination is typically low in cells; two, an active nuclease presents a risk of introducing permanent off-target mutations; and three, prevalent programmable nucleases typically comprise elements of non-human origin raising the potential ofin vivoimmunogenicity. In light of these, approaches to instead directly target RNA, and use of molecular machinery native to the host would be highly desirable. Towards this, we engineered and optimized two complementary approaches, referred together hereon astRiAD, based on the use oftRNAsin codon suppression andadenosinedeaminases in RNA editing. Specifically, by delivering modified endogenous tRNAs and/or the RNA editing enzyme ADAR2 and an associated guiding RNA (adRNA) via adeno-associated viruses, we enabled premature stop codon read-through and correction in themdxmouse model of muscular dystrophy that harbors a nonsense mutation in the dystrophin gene. We further demonstrated inducible restoration of dystrophin expression by pyrolysyl-tRNA mediated incorporation of unnatural amino acids (UAAs) at the stop codon. Additionally, we also engineered ADAR2 mediated correction of a point mutation in liver RNA of thespfashmouse model of ornithine transcarbamylase (OTC) deficiency. Taken together, our results establish the use of suppressor tRNAs and ADAR2 forin vivoRNA targeting, and this integrated tRiAD approach is robust, genomically scarless, and potentially non-immunogenic as it utilizes effector RNAs and human proteins.

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