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Background Mutations in the POT1 gene explain abnormally long telomeres and multiple tumors including cardiac angiosarcomas (CAS). However, the link between long telomeres and tumorigenesis is poorly understood. Methods and Results Here, we have studied the somatic landscape of 3 different angiosarcoma patients with mutations in the POT1 gene to further investigate this tumorigenesis process. In addition, the genetic landscape of 7 CAS patients without mutations in the POT1 gene has been studied. Patients with CAS and nonfunctional POT1 did not repress ATR (ataxia telangiectasia RAD3-related)-dependent DNA damage signaling and showed a constitutive increase of cell cycle arrest and somatic activating mutations in the VEGF (vascular endothelial growth factor)/angiogenesis pathway ( KDR gene). The same observation was made in POT1 mutation carriers with tumors different from CAS and also in CAS patients without mutations in the POT1 gene but with mutations in other genes involved in DNA damage signaling. Conclusions Inhibition of POT1 function and damage-response malfunction activated DNA damage signaling and increased cell cycle arrest as well as interfered with apoptosis, which would permit acquisition of somatic mutations in the VEGF/angiogenesis pathway that drives tumor formation. Therapies based on the inhibition of damage signaling in asymptomatic carriers may diminish defects on cell cycle arrest and thus prevent the apoptosis deregulation that leads to the acquisition of driver mutations.

Objective: To provide a comprehensive overview of all detected mutations in the ABCA4 gene in Spanish families with autosomal recessive retinal disorders, including Stargardt's disease (arSTGD), cone-rod dystrophy (arCRD), and retinitis pigmentosa (arRP), and to assess genotype-phenotype correlation and disease progression in 10 years by considering the type of variants and age at onset., Design: Case series., Participants: A total of 420 unrelated Spanish families: 259 arSTGD, 86 arCRD, and 75 arRP., Methods: Spanish families were analyzed through a combination of ABCR400 genotyping microarray, denaturing high-performance liquid chromatography, and high-resolution melting scanning. Direct sequencing was used as a confirmation technique for the identified variants. Screening by multiple ligation probe analysis was used to detect possible large deletions or insertions in the ABCA4 gene. Selected families were analyzed further by next generation sequencing., Main Outcome Measures: DNA sequence variants, mutation detection rates, haplotypes, age at onset, central or peripheral vision loss, and night blindness., Results: Overall, we detected 70.5% and 36.6% of all expected ABCA4 mutations in arSTGD and arCRD patient cohorts, respectively. In the fraction of the cohort where the ABCA4 gene was sequenced completely, the detection rates reached 73.6% for arSTGD and 66.7% for arCRD. However, the frequency of possibly pathogenic ABCA4 alleles in arRP families was only slightly higher than that in the general population. Moreover, in some families, mutations in other known arRP genes segregated with the disease phenotype., Conclusions: An increasing understanding of causal ABCA4 alleles in arSTGD and arCRD facilitates disease diagnosis and prognosis and also is paramount in selecting patients for emerging clinical trials of therapeutic interventions. Because ABCA4-associated diseases are evolving retinal dystrophies, assessment of age at onset, accurate clinical diagnosis, and genetic testing are crucial. We suggest that ABCA4 mutations may be associated with a retinitis pigmentosa-like phenotype often as a consequence of severe (null) mutations, in cases of long-term, advanced disease, or both. Patients with classical arRP phenotypes, especially from the onset of the disease, should be screened first for mutations in known arRP genes and not ABCA4., (Copyright © 2013 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Background: CRB1 mutations are reported as cause of severe congenital and early-onset retinal dystrophies (EORD) with different phenotypic manifestations, including Leber congenital amaurosis (LCA), retinitis pigmentosa (RP) and cone-rod dystrophies. Comprehensive mutational scanning of the whole gene has been only performed in few cohorts, mainly in LCA patients. Here, we aimed investigating the real prevalence of CRB1 mutations in the Spanish population by extensive screening of CRB1 mutations in a large cohort of LCA and EORP cases., Methods: This report integrates data from previous studies on CRB1 defects in our Spanish cohort of LCA and early-onset RP (EORP) with new findings from a comprehensive mutational screening of the whole gene. The molecular tools used include mutation genotyping arrays, whole-genome homozygosity mapping, an optimized high-resolution melting (HRM) analysis and Sanger sequencing., Results: A large clinically well-characterized cohort of 404 Spanish cases was studied, 114 of which suffered from LCA and 290 from EORP. This study reveals that 11% of Spanish patients carried mutations in CRB1, ranging from 9% of EORP to 14% of LCA cases. More than three quarters of the mutations identified herein have been first described in this Spanish cohort, 13 of them are unreported new variants and 13 had been previously reported in our previous studies., Conclusions: This work provides a wide spectrum of CRB1 mutations in the Spanish EORD patients and evidences the major role of CRB1 as causal gene in the Spanish EORP patients. It is noteworthy that a high rate of private mutations only described in our cohort has been found so far. To our knowledge, this study represents the most complete mutational screening of CRB1 in a Spanish LCA and EORP cohort, allowing us to establish gene-specific frequencies and to provide a wide spectrum of CRB1 mutations in the Spanish population.

Purpose: Mutations in ABCA4 have been associated with autosomal recessive Stargardt disease, autosomal recessive cone-rod dystrophy, and autosomal recessive retinitis pigmentosa. The purpose of this study was to determine (1) associations among mutations and polymorphisms and (2) the role of the polymorphisms as protector/risk factors., Methods: A case-control study was designed in which 128 Spanish patients and 84 control individuals were analyzed. Patient samples presented one or two mutated alleles previously identified using ABCR400 microarray and sequencing., Results: A total of 18 previously described polymorphisms were studied in patients and control individuals. All except one presented a polymorphisms frequency higher than 5% in patients, and five mutations were found to have a frequency >5%. The use of statistical methods showed that the frequency of the majority of polymorphisms was similar in patients and controls, except for the IVS10+5delG, p.Asn1868Ile, IVS48+21C>T, and p.Arg943Gln polymorphisms. In addition, IVS48+21C>T and p.Arg943Gln were found to be in linkage disequilibrium with the p.Gly1961Glu and p.Arg602Trp mutations, respectively., Conclusions: Although the high allelic heterogeneity in ABCA4 and the wide spectrum of many common and rare polymorphisms complicate the interpretation of clinical relevance, polymorphisms were identified that may act as risk factors (p.Asn1868Ile) and others that may act as protection factors (p.His423Arg and IVS10+5 delG).

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.

Background: This study was undertaken to analyse the OA1 gene (GPR143) and its involvement in a Spanish family presenting with nystagmus, a common symptom of X-linked ocular albinism (XLOA)., Methods: DNA samples from the index case and eight relatives were analysed by multiplex ligation-dependent probe amplification (MLPA). Sequence analysis and restriction assay were used to confirm the results. In addition, an analysis of a STR located in intron 1 of the OA1 gene (OA-CA) was performed., Results: The father of the proband presented with nystagmus, a feature consistent with XLOA. Mutation screening by multiplex ligation-dependent probe amplification and sequence analysis of the exon 2 of the OA1 gene led to the identification of the novel p.Glu129fsX35 (g.5815delA) mutation in two affected males and four carrier females. Three relatives were found to be non-mutated. The deletion detected resulted in a truncated protein 35 codons downstream and generated a new restriction site for the XcmI endonuclease. Additionally, microsatellite analysis showed co-segregation with the disease in the family., Conclusions: A novel deletion in the OA1 gene was identified in a Spanish family with ocular albinism. The mutation detected is likely a loss-of-function alteration. To the best of our knowledge, we describe the first Spanish family known to present with XLOA due to mutations in the OA1 gene.