Caracterización clínica y genética de familias españolas afectadas de retinosis pigmentaria: casos recesivos y esporádicos

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología. Fecha de lectura: 14-04-201

Identification of genomic regions regulating sex determination in Atlantic salmon using high density SNP data

Background: A complete understanding of the genetic basis for sexual determination and differentiation is necessary in order to implement efficient breeding schemes at early stages of development. Atlantic salmon belongs to the family Salmonidae of fishes and represents a species of great commercial value. Although the species is assumed to be male heterogametic with XY sex determination, the precise genetic basis of sexual development remains unclear. The complexity is likely associated to the relatively recent salmonid specific whole genome duplication that may be responsible for certain genome instability. This instability together with the capacity of the sex-determining gene to move across the genome as reported by previous studies, may explain that sexual development genes are not circumscribed to the same chromosomes in all members of the species. In this study, we have used a 220 K SNP panel developed for Atlantic salmon to identify the chromosomes explaining the highest proportion of the genetic variance for sex as well as candidate regions and genes associated to sexual development in this species. Results: Results from regional heritability analysis showed that the chromosomes explaining the highest proportion of variance in these populations were Ssa02 (heritability = 0.42, SE = 0.12) and Ssa21 (heritability = 0.26, SE = 0.11). After pruning by linkage disequilibrium, genome-wide association analyses revealed 114 SNPs that were significantly associated with sex, being Ssa02 the chromosome containing a greatest number of regions. Close examination of the candidate regions evidenced important genes related to sex in other species of Class Actinopterygii, including SDY, genes from family SOX, RSPO1, ESR1, U2AF2A, LMO7, GNRH-R, DND and FIGLA. Conclusions: The combined results from regional heritability analysis and genome-wide association have provided new advances in the knowledge of the genetic regulation of sex determination in Atlantic salmon, supporting that Ssa02 is the candidate chromosome for sex in this species and suggesting an alternative population lineage in Spanish wild populations according to the results from Ssa21.Ministerio de Economía y Competitividad | Ref. RZ2012–00011-C02–00Ministerio de Ciencia e Innovación | Ref. JCI-2011-1089

Mutation analysis of 272 Spanish families affected by autosomal recessive retinitis pigmentosa using a genotyping microarray

Contains fulltext : 89342.pdf (publisher's version ) (Open Access)PURPOSE: Retinitis pigmentosa (RP) is a genetically heterogeneous disorder characterized by progressive loss of vision. The aim of this study was to identify the causative mutations in 272 Spanish families using a genotyping microarray. METHODS: 272 unrelated Spanish families, 107 with autosomal recessive RP (arRP) and 165 with sporadic RP (sRP), were studied using the APEX genotyping microarray. The families were also classified by clinical criteria: 86 juveniles and 186 typical RP families. Haplotype and sequence analysis were performed to identify the second mutated allele. RESULTS: At least one-gene variant was found in 14% and 16% of the juvenile and typical RP groups respectively. Further study identified four new mutations, providing both causative changes in 11% of the families. Retinol Dehydrogenase 12 (RDH12) was the most frequently mutated gene in the juvenile RP group, and Usher Syndrome 2A (USH2A) and Ceramide Kinase-Like (CERKL) were the most frequently mutated genes in the typical RP group. The only variant found in CERKL was p.Arg257Stop, the most frequent mutation. CONCLUSIONS: The genotyping microarray combined with segregation and sequence analysis allowed us to identify the causative mutations in 11% of the families. Due to the low number of characterized families, this approach should be used in tandem with other techniques

Genotype–phenotype correlation in patients with Usher syndrome and pathogenic variants in MYO7A: implications for future clinical trials

Purpose: We aimed to establish correlations between the clinical features of a cohort of Usher syndrome (USH) patients with pathogenic variants in MYO7A, type of pathogenic variant, and location on the protein domain. Methods: Sixty-two USH patients from 46 families with biallelic variants in MYO7A were examined for visual and audiological features. Participants were evaluated based on self-reported ophthalmological history and ophthalmological investigations (computerized visual field testing, best-corrected visual acuity, and ophthalmoscopic and electrophysiological examination). Optical coherence tomography and fundus autofluorescence imaging were performed when possible. Auditory and vestibular functions were evaluated. Patients were classified according to the type of variant and the protein domain where the variants were located. Results: Most patients displayed a typical USH1 phenotype, that is, prelingual severe-profound sensorineural hearing loss, prepubertal retinitis pigmentosa (RP) and vestibular dysfunction. No statistically significant differences were observed for the variables analysed except for the onset of hearing loss due to the existence of two USH2 cases, defined as postlingual sensorineural hearing loss, postpubertal onset of RP, and absence of vestibular dysfunction, and one atypical case of USH. Conclusion: We were unable to find a correlation between genotype and phenotype for MYO7A. However, our findings could prove useful for the assessment of efficacy in clinical trials, since the type of MYO7A variant does not seem to change the onset, severity or course of visual disease.This project was financially supported by the Center for Biomedical Network Research on Rare Diseases (CIBERER), FIS (PI16/00425, PI16/00539 and IIS‐FJD Biobank PT13/0010/0012). LG‐M and IPR were supported by the Río Hortega and predoctoral Programs (CM16/00126 and FI17/00192, respectively) from Institute of Health Carlos III (ISCIII, Spanish Ministry of the Economy, Industry and Competitiveness), Regional Government of Madrid (CAM, B2017/BMD37), and Regional Government of the Valencian Community (PROMETEU/2018/135), with partial support from the European Regional Development Fund (ERDF). Additional support was received from the Ramon Areces Foundation, the University Chair UAM‐IIS‐FJD of Genomic Medicine, ONCE Foundation and the Spanish National Organization of the Blind (ONCE). Drafting of this manuscript was possible thanks to the UshTher project (Clinical trial of gene therapy with dual AAV vectors for retinitis pigmentosa in patients with Usher syndrome type IB), which has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 754848. The authors are grateful to the families that participated in this study and to the colleagues who referred patients to us. We also thank the Genetics and Ophthalmology Departments of Fundación Jimenez Diaz University Hospital (FJD, Madrid) and Asunción Giménez, Cristina Villaverde, and Ignacio Mahillo for their technical assistance

Whole-exome sequencing reveals ZNF408 as a new gene associated with autosomal recessive retinitis pigmentosa with vitreal alterations

Retinitis pigmentosa (RP) is a group of progressive inherited retinal dystrophies that cause visual impairment as a result of photoreceptor cell death. RP is heterogeneous, both clinically and genetically making difficult to establish precise genotype–phenotype correlations. In a Spanish family with autosomal recessive RP (arRP), homozygosity mapping and whole-exome sequencing led to the identification of a homozygous mutation (c.358_359delGT; p.Ala122Leufs*2) in the ZNF408 gene. A screening performed in 217 additional unrelated families revealed another homozygous mutation (c.1621C>T; p.Arg541Cys) in an isolated RP case. ZNF408 encodes a transcription factor that harbors 10 predicted C2H2-type fingers thought to be implicated in DNA binding. To elucidate the ZNF408 role in the retina and the pathogenesis of these mutations we have performed different functional studies. By immunohistochemical analysis in healthy human retina, we identified that ZNF408 is expressed in both cone and rod photoreceptors, in a specific type of amacrine and ganglion cells, and in retinal blood vessels. ZNF408 revealed a cytoplasmic localization and a nuclear distribution in areas corresponding with the euchromatin fraction. Immunolocalization studies showed a partial mislocalization of the p.Arg541Cys mutant protein retaining part of the WT protein in the cytoplasm. Our study demonstrates that ZNF408, previously associated with Familial Exudative Vitreoretinopathy (FEVR), is a new gene causing arRP with vitreous condensations supporting the evidence that this protein plays additional functions into the human retina.This work is supported by CIBERER (06/07/0036), FIS (PI013/00226), Ministry of Economy and Competitiveness-FEDER (BFU2012-36845), RETICS (RD12/0034/0010), Fundación ONCE, Fundaluce and grants BIO2011-27069 from the Spanish Ministry of Economy and Competitiveness, and PROMETEOII/2014/025 from the Conselleria de Educacio of the Valencia Community. PC is supported by Fundación Conchita Rábago (FCR), MC by Miguel Servet ISCIII (CP/03256) and dS by CAPES Foundation, Ministry of Education of Brazil

An evaluation of pipelines for DNA variant detection can guide a reanalysis protocol to increase the diagnostic ratio of genetic diseases

Clinical exome (CE) sequencing has become a first-tier diagnostic test for hereditary diseases; however, its diagnostic rate is around 30–50%. In this study, we aimed to increase the diagnostic yield of CE using a custom reanalysis algorithm. Sequencing data were available for three cohorts using two commercial protocols applied as part of the diagnostic process. Using these cohorts, we compared the performance of general and clinically relevant variant calling and the efficacy of an in-house bioinformatic protocol (FJD-pipeline) in detecting causal variants as compared to commercial protocols. On the whole, the FJD-pipeline detected 99.74% of the causal variants identified by the commercial protocol in previously solved cases. In the unsolved cases, FJD-pipeline detects more INDELs and non-exonic variants, and is able to increase the diagnostic yield in 2.5% and 3.2% in the re-analysis of 78 cancer and 62 cardiovascular cases. These results were considered to design a reanalysis, filtering and prioritization algorithm that was tested by reassessing 68 inconclusive cases of monoallelic autosomal recessive retinal dystrophies increasing the diagnosis by 4.4%. In conclusion, a guided NGS reanalysis of unsolved cases increases the diagnostic yield in genetic disorders, making it a useful diagnostic tool in medical geneticsWe want to thank the participants for consenting to the use of their data for the study. We would like to thank all technical staff in the genetics service of the Fundación Jiménez Díaz University Hospital for conducting the sequencing and segregation analysis. We also thank Oliver Shaw (IIS-FJD) for editorial assistance. This work was supported by the Instituto de Salud Carlos III (ISCIII) of the Spanish Ministry of Health (FIS; PI16/00425, PI19/00321, PI18/00579 and PI20/00851), Centro de Investigación Biomédica en Red Enfermedades Raras (CIBERER, 06/07/0036), IIS-FJD BioBank (PT13/0010/0012), Comunidad de Madrid (CAM, RAREGenomics Project, B2017/BMD-3721), Ramón Areces Foundation (4019/012), Conchita Rábago Foundation, and the University Chair UAM-IIS-FJD of Genomic Medicine. R.R. is supported by a postdoctoral fellowship of the Comunidad de Madrid (2019-T2/BMD-13714), L.d.l.F. is supported by the platform technician contract of ISCIII (CA18/00017), IPR is supported by a PhD studentship from the predoctoral program from ISCIII (FI17/ 00192), I.F.I. is supported by a grant from the Comunidad de Madrid (CAM, PEJ-2017- AI/BMD7256), G.N.M. is supported by a grant from the Comunidad de Madrid (PEJ2020-AI/BMD-18610), A.D. is supported by a PhD studentship from the predoctoral program from ISCIII (FI18/00123), B.A. is supported by a Juan Rodes program from ISCIII (JR17/00020), C.R. is supported by a PhD studentship from the Conchita Rabago Foundation and PM and MC are supported by a Miguel Servet program contract from ISCIII (CP16/00116 and CPII17/00006, respectively). The funders played no role in study design, data collection, data analysis, manuscript preparation, and/or publication decision

Combining targeted panel-based resequencing and copy-number variation analysis for the diagnosis of inherited syndromic retinopathies and associated ciliopathies

Inherited syndromic retinopathies are a highly heterogeneous group of diseases that involve retinal anomalies and systemic manifestations. They include retinal ciliopathies, other well-defined clinical syndromes presenting with retinal alterations and cases of non-specific multisystemic diseases. The heterogeneity of these conditions makes molecular and clinical characterization of patients challenging in daily clinical practice. We explored the capacity of targeted resequencing and copy-number variation analysis to improve diagnosis of a heterogeneous cohort of 47 patients mainly comprising atypical cases that did not clearly fit a specific clinical diagnosis. Thirty-three likely pathogenic variants were identified in 18 genes (ABCC6, ALMS1, BBS1, BBS2, BBS12, CEP41, CEP290, IFT172, IFT27, MKKS, MYO7A, OTX2, PDZD7, PEX1, RPGRIP1, USH2A, VPS13B, and WDPCP). Molecular findings and additional clinical reassessments made it possible to accurately characterize 14 probands (30% of the total). Notably, clinical refinement of complex phenotypes was achieved in 4 cases, including 2 de novo OTX2-related syndromes, a novel phenotypic association for the ciliary CEP41 gene, and the co-existence of biallelic USH2A variants and a Koolen-de-Vries syndrome–related 17q21.31 microdeletion. We demonstrate that combining next-generation sequencing and CNV analysis is a comprehensive and useful approach to unravel the extensive phenotypic and genotypic complexity of inherited syndromic retinopathiesFEDER (Fondo Europeo de Desarrollo Regional) | Ref. PI016/00425Instituto de Salud Carlos III | Ref. PT13/0010/001

CSVS, a crowdsourcing database of the Spanish population genetic variability

The knowledge of the genetic variability of the local population is of utmost importance in personalized medicine and has been revealed as a critical factor for the discovery of new disease variants. Here, we present the Collaborative Spanish Variability Server (CSVS), which currently contains more than 2000 genomes and exomes of unrelated Spanish individuals. This database has been generated in a collaborative crowdsourcing effort collecting sequencing data produced by local genomic projects and for other purposes. Sequences have been grouped by ICD10 upper categories. A web interface allows querying the database removing one or more ICD10 categories. In this way, aggregated counts of allele frequencies of the pseudo-control Spanish population can be obtained for diseases belonging to the category removed. Interestingly, in addition to pseudo-control studies, some population studies can be made, as, for example, prevalence of pharmacogenomic variants, etc. In addition, this genomic data has been used to define the first Spanish Genome Reference Panel (SGRP1.0) for imputation. This is the first local repository of variability entirely produced by a crowdsourcing effort and constitutes an example for future initiatives to characterize local variabilityworldwide. CSVS is also part of the GA4GH Beacon network.Spanish Ministry of Economy and Competitiveness SAF2017-88908-R PT17/0009/0006 PI19/00321 CIBERER ACCI-06/07/0036 PI14-948 PI171659Regional Government of Madrid, RAREGenomicsCM B2017/BMD3721 B2017/BMD-3721European Union (EU)European Union (EU) 676559University Chair UAM-IIS-FJD of Genomic MedicineRamon Areces Foundatio