Hotspot mutations in the spliceosome gene SF3B1 are reported in B20% of uveal melanomas. SF3B1 is involved in 3 0 -splice site (3 0 ss) recognition during RNA splicing; however, the molecular mechanisms of its mutation have remained unclear. Here we show, using RNA-Seq analyses of uveal melanoma, that the SF3B1 R625/K666 mutation results in deregulated splicing at a subset of junctions, mostly by the use of alternative 3 0 ss. Modelling the differential junctions in SF3B1 WT and SF3B1 R625/K666 cell lines demonstrates that the deregulated splice pattern strictly depends on SF3B1 status and on the 3'ss-sequence context. SF3B1 WT knockdown or overexpression do not reproduce the SF3B1 R625/K666 splice pattern, qualifying SF3B1 R625/K666 as change-of-function mutants. Mutagenesis of predicted branchpoints reveals that the SF3B1 R625/K666 -promoted splice pattern is a direct result of alternative branchpoint usage. Altogether, this study provides a better understanding of the mechanisms underlying splicing alterations induced by mutant SF3B1 in cancer, and reveals a role for alternative branchpoints in disease.

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Background. Italy was the first western country to face an uncontrolled outbreak of SARS-CoV-2 infection. The epidemic began in March 2020 within a context characterised by a general lack of knowledge about the disease. The first scientific evidence emerged months later, leading to treatment changes. The aim of our study was to evaluate the effects of these changes. Methods. Data from a hospital in Genoa, Italy, were analysed. Patients deceased from SARS-CoV-2 infection were selected. Data were compared by dividing patients into two cohorts: “phase A” (March–May 2020) and “phase B” (October–December 2020). Results. A total of 5142 patients were admitted. There were 274 SARS-CoV-2-related deaths (162 phase A and 112 phase B). No differences were observed in terms of demographics, presentation, or comorbidities. A significant increase was recorded in corticosteroid use. Mortality was 33.36% during phase A, falling to 21.71% during phase B. When subdividing the trend during the two phases by age, we found a difference in people aged 65–74 years. Conclusions. There is scarce evidence regarding treatment for SARS-CoV-2 (especially for severe infection). However, treatment changes improved the prognosis for people under the age of 75. The prognosis for older people remains poor, despite the improvements achieved.

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