scholarly journals Updating the Genetic Landscape of Inherited Retinal Dystrophies

2021 ◽  
Vol 9 ◽  
Author(s):  
Belén García Bohórquez ◽  
Elena Aller ◽  
Ana Rodríguez Muñoz ◽  
Teresa Jaijo ◽  
Gema García García ◽  
...  
Keyword(s):  
Genetic Diagnosis ◽  
Diagnostic Process ◽  
Reproductive Decisions ◽  
Inherited Retinal Dystrophies ◽  
Pathogenic Variants ◽  
Retinal Dystrophies ◽  
Genetic Landscape ◽  
Custom Panel ◽  
Generation Sequencing ◽  
Autosomal Recessive Pattern

Inherited retinal dystrophies (IRD) are a group of diseases characterized by the loss or dysfunction of photoreceptors and a high genetic and clinical heterogeneity. Currently, over 270 genes have been associated with IRD which makes genetic diagnosis very difficult. The recent advent of next generation sequencing has greatly facilitated the diagnostic process, enabling to provide the patients with accurate genetic counseling in some cases. We studied 92 patients who were clinically diagnosed with IRD with two different custom panels. In total, we resolved 53 patients (57.6%); in 12 patients (13%), we found only one mutation in a gene with a known autosomal recessive pattern of inheritance; and 27 patients (29.3%) remained unsolved. We identified 120 pathogenic or likely pathogenic variants; 30 of them were novel. Among the cone-rod dystrophy patients, ABCA4 was the most common mutated gene, meanwhile, USH2A was the most prevalent among the retinitis pigmentosa patients. Interestingly, 10 families carried pathogenic variants in more than one IRD gene, and we identified two deep-intronic variants previously described as pathogenic in ABCA4 and CEP290. In conclusion, the IRD study through custom panel sequencing demonstrates its efficacy for genetic diagnosis, as well as the importance of including deep-intronic regions in their design. This genetic diagnosis will allow patients to make accurate reproductive decisions, enroll in gene-based clinical trials, and benefit from future gene-based treatments.

scholarly journals Genetic landscape of 6089 inherited retinal dystrophies affected cases in Spain and their therapeutic and extended epidemiological implications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Irene Perea-Romero ◽  
◽  
Gema Gordo ◽  
Ionut F. Iancu ◽  
Marta Del Pozo-Valero ◽  
...  
Keyword(s):  
Genetic Diagnosis ◽  
Cross Sectional Study ◽  
Molecular Techniques ◽  
Cross Sectional ◽  
Autonomous Communities ◽  
Inherited Retinal Dystrophies ◽  
Pathogenic Variants ◽  
Retinal Dystrophies ◽  
Family Pedigree ◽  
Genetic Landscape

AbstractInherited retinal diseases (IRDs), defined by dysfunction or progressive loss of photoreceptors, are disorders characterized by elevated heterogeneity, both at the clinical and genetic levels. Our main goal was to address the genetic landscape of IRD in the largest cohort of Spanish patients reported to date. A retrospective hospital-based cross-sectional study was carried out on 6089 IRD affected individuals (from 4403 unrelated families), referred for genetic testing from all the Spanish autonomous communities. Clinical, demographic and familiar data were collected from each patient, including family pedigree, age of appearance of visual symptoms, presence of any systemic findings and geographical origin. Genetic studies were performed to the 3951 families with available DNA using different molecular techniques. Overall, 53.2% (2100/3951) of the studied families were genetically characterized, and 1549 different likely causative variants in 142 genes were identified. The most common phenotype encountered is retinitis pigmentosa (RP) (55.6% of families, 2447/4403). The most recurrently mutated genes were PRPH2, ABCA4 and RS1 in autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL) NON-RP cases, respectively; RHO, USH2A and RPGR in AD, AR and XL for non-syndromic RP; and USH2A and MYO7A in syndromic IRD. Pathogenic variants c.3386G > T (p.Arg1129Leu) in ABCA4 and c.2276G > T (p.Cys759Phe) in USH2A were the most frequent variants identified. Our study provides the general landscape for IRD in Spain, reporting the largest cohort ever presented. Our results have important implications for genetic diagnosis, counselling and new therapeutic strategies to both the Spanish population and other related populations.

scholarly journals The Genetic Landscape of Inherited Retinal Diseases in a Mexican Cohort: Genes, Mutations and Phenotypes

Genes ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1824
Author(s):  
Cristina Villanueva-Mendoza ◽  
Miquel Tuson ◽  
David Apam-Garduño ◽  
Marta de Castro-Miró ◽  
Raul Tonda ◽  
...  
Keyword(s):  
Diagnostic Yield ◽  
Novel Mutation ◽  
Genetic Diagnosis ◽  
Inherited Retinal Dystrophies ◽  
Pathogenic Variants ◽  
Retinal Dystrophies ◽  
Whole Exome ◽  
Genetic Landscape ◽  
Genetic Features ◽  
Gene Panels

In this work, we aimed to provide the genetic diagnosis of a large cohort of patients affected with inherited retinal dystrophies (IRDs) from Mexico. Our data add valuable information to the genetic portrait in rare ocular diseases of Mesoamerican populations, which are mostly under-represented in genetic studies. A cohort of 144 unrelated probands with a clinical diagnosis of IRD were analyzed by next-generation sequencing using target gene panels (overall including 346 genes and 65 intronic sequences). Four unsolved cases were analyzed by whole-exome sequencing (WES). The pathogenicity of new variants was assessed by in silico prediction algorithms and classified following the American College of Medical Genetics and Genomics (ACMG) guidelines. Pathogenic or likely pathogenic variants were identified in 105 probands, with a final diagnostic yield of 72.9%; 17 cases (11.8%) were partially solved. Eighteen patients were clinically reclassified after a genetic diagnostic test (17.1%). In our Mexican cohort, mutations in 48 genes were found, with ABCA4, CRB1, RPGR and USH2A as the major contributors. Notably, over 50 new putatively pathogenic variants were identified. Our data highlight cases with relevant clinical and genetic features due to mutations in the RAB28 and CWC27 genes, enrich the novel mutation repertoire and expand the IRD landscape of the Mexican population.

scholarly journals Whole exome sequencing in 17 consanguineous Iranian pedigrees expands the mutational spectrum of inherited retinal dystrophies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Atta Ur Rehman ◽  
Neda Sepahi ◽  
Nicola Bedoni ◽  
Zeinab Ravesh ◽  
Arash Salmaninejad ◽  
...  
Keyword(s):  
Disease Genes ◽  
Homozygous State ◽  
Traditional Practice ◽  
Genomic Variants ◽  
Mutational Spectrum ◽  
Inherited Retinal Dystrophies ◽  
Retinal Dystrophies ◽  
Whole Exome ◽  
Human Disorders ◽  
Generation Sequencing

AbstractInherited retinal dystrophies (IRDs) constitute one of the most heterogeneous groups of Mendelian human disorders. Using autozygome-guided next-generation sequencing methods in 17 consanguineous pedigrees of Iranian descent with isolated or syndromic IRD, we identified 17 distinct genomic variants in 11 previously-reported disease genes. Consistent with a recessive inheritance pattern, as suggested by pedigrees, variants discovered in our study were exclusively bi-allelic and mostly in a homozygous state (in 15 families out of 17, or 88%). Out of the 17 variants identified, 5 (29%) were never reported before. Interestingly, two mutations (GUCY2D:c.564dup, p.Ala189ArgfsTer130 and TULP1:c.1199G > A, p.Arg400Gln) were also identified in four separate pedigrees (two pedigrees each). In addition to expanding the mutational spectrum of IRDs, our findings confirm that the traditional practice of endogamy in the Iranian population is a prime cause for the appearance of IRDs.

scholarly journals Genetic analyses of the NF1 gene in Turkish neurofibromatosis type I patients and definition of three novel variants

2017 ◽  
Vol 20 (1) ◽  
pp. 13-20 ◽  
Author(s):  
SD Ulusal ◽  
H Gürkan ◽  
E Atlı ◽  
SA Özal ◽  
M Çiftdemir ◽  
...  
Keyword(s):  
Next Generation Sequencing ◽  
Genetic Diagnosis ◽  
Neurofibromatosis Type ◽  
Type I ◽  
Neurofibromatosis Type I ◽  
Next Generation ◽  
Loss Of Function ◽  
Pathogenic Variants ◽  
Nf1 Gene ◽  
Generation Sequencing

Abstract Neurofibromatosis Type I (NF1) is a multi systemic autosomal dominant neurocutaneous disorder predisposing patients to have benign and/or malignant lesions predominantly of the skin, nervous system and bone. Loss of function mutations or deletions of the NF1 gene is responsible for NF1 disease. Involvement of various pathogenic variants, the size of the gene and presence of pseudogenes makes it difficult to analyze. We aimed to report the results of 2 years of multiplex ligation-dependent probe amplification (MLPA) and next generation sequencing (NGS) for genetic diagnosis of NF1 applied at our genetic diagnosis center. The MLPA, semiconductor sequencing and Sanger sequencing were performed in genomic DNA samples from 24 unrelated patients and their affected family members referred to our center suspected of having NF1. In total, three novel and 12 known pathogenic variants and a whole gene deletion were determined. We suggest that next generation sequencing is a practical tool for genetic analysis of NF1. Deletion/duplication analysis with MLPA may also be helpful for patients clinically diagnosed to carry NF1 but do not have a detectable mutation in NGS.

scholarly journals VarGenius-HZD Allows Accurate Detection of Rare Homozygous or Hemizygous Deletions in Targeted Sequencing Leveraging Breadth of Coverage

Genes ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1979
Author(s):  
Francesco Musacchia ◽  
Marianthi Karali ◽  
Annalaura Torella ◽  
Steve Laurie ◽  
Valeria Policastro ◽  
...  
Keyword(s):  
Genetic Diagnosis ◽  
Targeted Sequencing ◽  
Sequencing Data ◽  
Scalable Algorithm ◽  
1000 Genomes ◽  
Inherited Retinal Dystrophies ◽  
Retinal Dystrophies ◽  
Homozygous Deletions ◽  
Selection Of ◽  
Higher Sensitivity

Homozygous deletions (HDs) may be the cause of rare diseases and cancer, and their discovery in targeted sequencing is a challenging task. Different tools have been developed to disentangle HD discovery but a sensitive caller is still lacking. We present VarGenius-HZD, a sensitive and scalable algorithm that leverages breadth-of-coverage for the detection of rare homozygous and hemizygous single-exon deletions (HDs). To assess its effectiveness, we detected both real and synthetic rare HDs in fifty exomes from the 1000 Genomes Project obtaining higher sensitivity in comparison with state-of-the-art algorithms that each missed at least one event. We then applied our tool on targeted sequencing data from patients with Inherited Retinal Dystrophies and solved five cases that still lacked a genetic diagnosis. We provide VarGenius-HZD either stand-alone or integrated within our recently developed software, enabling the automated selection of samples using the internal database. Hence, it could be extremely useful for both diagnostic and research purposes.

Scaling New Heights in the Genetic Diagnosis of Inherited Retinal Dystrophies

2019 ◽  
pp. 215-219 ◽  
Author(s):  
Roser Gonzàlez-Duarte ◽  
Marta de Castro-Miró ◽  
Miquel Tuson ◽  
Valeria Ramírez-Castañeda ◽  
Rebeca Valero Gils ◽  
...  
Keyword(s):  
Genetic Diagnosis ◽  
Inherited Retinal Dystrophies ◽  
Retinal Dystrophies

scholarly journals Author Correction: Genetic landscape of 6089 inherited retinal dystrophies affected cases in Spain and their therapeutic and extended epidemiological implications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Irene Perea-Romero ◽  
◽  
Gema Gordo ◽  
Ionut F. Iancu ◽  
Marta Del Pozo-Valero ◽  
...  
Keyword(s):  
Inherited Retinal Dystrophies ◽  
Retinal Dystrophies ◽  
Genetic Landscape

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

scholarly journals Prioritizing variants of uncertain significance for reclassification using a rule-based algorithm in inherited retinal dystrophies

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Ionut-Florin Iancu ◽  
Almudena Avila-Fernandez ◽  
Ana Arteche ◽  
Maria Jose Trujillo-Tiebas ◽  
Rosa Riveiro-Alvarez ◽  
...  
Keyword(s):  
Exome Sequencing ◽  
Rare Diseases ◽  
Molecular Diagnostic ◽  
Rule Based ◽  
Variants Of Uncertain Significance ◽  
Inherited Retinal Dystrophies ◽  
Pathogenic Variants ◽  
Retinal Dystrophies ◽  
Clinical Exome Sequencing ◽  
Uncertain Significance

AbstractInherited retinal dystrophies (IRD) are a highly heterogeneous group of rare diseases with a molecular diagnostic rate of >50%. Reclassification of variants of uncertain significance (VUS) poses a challenge for IRD diagnosis. We collected 668 IRD cases analyzed by our geneticists using two different clinical exome-sequencing tests. We identified 114 unsolved cases pending reclassification of 125 VUS and studied their genomic, functional, and laboratory-specific features, comparing them to pathogenic and likely pathogenic variants from the same cohort (N = 390). While the clinical exome used did not show differences in diagnostic rate, the more IRD-experienced geneticist reported more VUS (p = 4.07e-04). Significantly fewer VUS were reported in recessive cases (p = 2.14e-04) compared to other inheritance patterns, and of all the genes analyzed, ABCA4 and IMPG2 had the lowest and highest VUS frequencies, respectively (p = 3.89e-04, p = 6.93e-03). Moreover, few frameshift and stop-gain variants were found to be informed VUS (p = 6.73e-08 and p = 2.93e-06). Last, we applied five pathogenicity predictors and found there is a significant proof of deleteriousness when all score for pathogenicity in missense variants. Altogether, these results provided input for a set of rules that correctly reclassified ~70% of VUS as pathogenic in validation datasets. Disease- and setting-specific features influence VUS reporting. Comparison with pathogenic and likely pathogenic variants can prioritize VUS more likely to be reclassified as causal.

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