Publications by authors named "Daniela Calini"

14 Publications

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CellMixS: quantifying and visualizing batch effects in single-cell RNA-seq data.

Life Sci Alliance 2021 06 23;4(6). Epub 2021 Mar 23.

Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland

A key challenge in single-cell RNA-sequencing (scRNA-seq) data analysis is batch effects that can obscure the biological signal of interest. Although there are various tools and methods to correct for batch effects, their performance can vary. Therefore, it is important to understand how batch effects manifest to adjust for them. Here, we systematically explore batch effects across various scRNA-seq datasets according to magnitude, cell type specificity, and complexity. We developed a cell-specific mixing score (cms) that quantifies mixing of cells from multiple batches. By considering distance distributions, the score is able to detect local batch bias as well as differentiate between unbalanced batches and systematic differences between cells of the same cell type. We compare metrics in scRNA-seq data using real and synthetic datasets and whereas these metrics target the same question and are used interchangeably, we find differences in scalability, sensitivity, and ability to handle differentially abundant cell types. We find that cell-specific metrics outperform cell type-specific and global metrics and recommend them for both method benchmarks and batch exploration.
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http://dx.doi.org/10.26508/lsa.202001004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7994321PMC
June 2021

muscat detects subpopulation-specific state transitions from multi-sample multi-condition single-cell transcriptomics data.

Nat Commun 2020 11 30;11(1):6077. Epub 2020 Nov 30.

Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland.

Single-cell RNA sequencing (scRNA-seq) has become an empowering technology to profile the transcriptomes of individual cells on a large scale. Early analyses of differential expression have aimed at identifying differences between subpopulations to identify subpopulation markers. More generally, such methods compare expression levels across sets of cells, thus leading to cross-condition analyses. Given the emergence of replicated multi-condition scRNA-seq datasets, an area of increasing focus is making sample-level inferences, termed here as differential state analysis; however, it is not clear which statistical framework best handles this situation. Here, we surveyed methods to perform cross-condition differential state analyses, including cell-level mixed models and methods based on aggregated pseudobulk data. To evaluate method performance, we developed a flexible simulation that mimics multi-sample scRNA-seq data. We analyzed scRNA-seq data from mouse cortex cells to uncover subpopulation-specific responses to lipopolysaccharide treatment, and provide robust tools for multi-condition analysis within the muscat R package.
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http://dx.doi.org/10.1038/s41467-020-19894-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7705760PMC
November 2020

Elevated Global DNA Methylation Is Not Exclusive to Amyotrophic Lateral Sclerosis and Is Also Observed in Spinocerebellar Ataxia Types 1 and 2.

Neurodegener Dis 2018 9;18(1):38-48. Epub 2018 Feb 9.

Suna and İnan Kıraç Foundation, Neurodegeneration Research Laboratory (NDAL), Molecular Biology and Genetics Department, Boğaziçi University, Istanbul, Turkey.

Adult-onset neurological disorders are caused and influenced by a multitude of different factors, including epigenetic modifications. Here, using an ELISA kit selected upon careful testing, we investigated global 5-methylcytosine (5-mC) levels in sporadic and familial amyotrophic lateral sclerosis (sALS and fALS), spinocerebellar ataxia types 1 and 2 (SCA1 and SCA2), Huntington's disease, Friedreich's ataxia, and myotonic dystrophy type 1. We report a significant elevation in global 5-mC levels of about 2-7% on average for sALS (p < 0.01 [F(1, 243) = 9.159, p = 0.0027]) and various forms of fALS along with SCA1 (p < 0.01 [F(1, 83) = 11.285], p = 0.0012) and SCA2 (p < 0.001 [F(1, 122) = 29.996, p = 0.0001]) when compared to age- and sex-matched healthy controls. C9orf72 expansion carrier ALS patients exhibit the highest global 5-mC levels along with C9orf72 promoter hypermethylation. We failed to measure global 5-hydroxymethylcytosine (5-hmC) levels in blood, probably due to the very low levels of 5-hmC and the limitations of the commercially available ELISA kits. Our results point towards a role for epigenetics modification in ALS, SCA1, and SCA2, and help conclude a dispute on the global 5-mC levels in sALS blood.
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http://dx.doi.org/10.1159/000486201DOI Listing
January 2019

The role of de novo mutations in the development of amyotrophic lateral sclerosis.

Hum Mutat 2017 11 3;38(11):1534-1541. Epub 2017 Aug 3.

Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy.

The genetic basis combined with the sporadic occurrence of amyotrophic lateral sclerosis (ALS) suggests a role of de novo mutations in disease pathogenesis. Previous studies provided some evidence for this hypothesis; however, results were conflicting: no genes with recurrent occurring de novo mutations were identified and different pathways were postulated. In this study, we analyzed whole-exome data from 82 new patient-parents trios and combined it with the datasets of all previously published ALS trios (173 trios in total). The per patient de novo rate was not higher than expected based on the general population (P = 0.40). We showed that these mutations are not part of the previously postulated pathways, and gene-gene interaction analysis found no enrichment of interacting genes in this group (P = 0.57). Also, we were able to show that the de novo mutations in ALS patients are located in genes already prone for de novo mutations (P < 1 × 10 ). Although the individual effect of rare de novo mutations in specific genes could not be assessed, our results indicate that, in contrast to previous hypothesis, de novo mutations in general do not impose a major burden on ALS risk.
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http://dx.doi.org/10.1002/humu.23295DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6599399PMC
November 2017

NEK1 variants confer susceptibility to amyotrophic lateral sclerosis.

Nat Genet 2016 09 25;48(9):1037-42. Epub 2016 Jul 25.

Neurogenetics Group, Division of Brain Sciences, Imperial College London, London, UK.

To identify genetic factors contributing to amyotrophic lateral sclerosis (ALS), we conducted whole-exome analyses of 1,022 index familial ALS (FALS) cases and 7,315 controls. In a new screening strategy, we performed gene-burden analyses trained with established ALS genes and identified a significant association between loss-of-function (LOF) NEK1 variants and FALS risk. Independently, autozygosity mapping for an isolated community in the Netherlands identified a NEK1 p.Arg261His variant as a candidate risk factor. Replication analyses of sporadic ALS (SALS) cases and independent control cohorts confirmed significant disease association for both p.Arg261His (10,589 samples analyzed) and NEK1 LOF variants (3,362 samples analyzed). In total, we observed NEK1 risk variants in nearly 3% of ALS cases. NEK1 has been linked to several cellular functions, including cilia formation, DNA-damage response, microtubule stability, neuronal morphology and axonal polarity. Our results provide new and important insights into ALS etiopathogenesis and genetic etiology.
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http://dx.doi.org/10.1038/ng.3626DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5560030PMC
September 2016

The validation of the Italian Edinburgh Cognitive and Behavioural ALS Screen (ECAS).

Amyotroph Lateral Scler Frontotemporal Degener 2016 Oct - Nov;17(7-8):489-498. Epub 2016 May 24.

a Department of Neurology and Laboratory of Neuroscience - IRCCS Istituto Auxologico Italiano , Milan , Italy.

This study presents the Italian validation of the recently developed Edinburgh Cognitive and Behavioural ALS Screen (ECAS), a short screen for cognitive/behavioural alterations in patients with amyotrophic lateral sclerosis (ALS). We evaluated the psychometric properties of the ECAS Italian version in terms of reliability and convergent validity for both cognitive and behavioural features. Furthermore, we investigated the relationship with affective and clinical variables, in addition to ECAS usability and patients' insight into cognitive/behaviour changes. Finally, correlations between genetic and cognitive/behavioural data were analysed. We recruited 107 patients with ALS. Normative data were collected on 248 healthy subjects. Participants were administered the ECAS and two standard cognitive screening tools (FAB, MoCA), two psychological questionnaires (BDI, STAI/Y) and an ad hoc usability questionnaire. The FBI was also carried out with caregivers. Results showed that the ECAS Italian version discriminated well between patients and controls. The most prevalent deficit occurred in executive functions and fluency. Correlations were observed between the ECAS and standard cognitive screening tools and between the ECAS carer interview and the FBI, supporting its full convergent validity. In conclusion, the ECAS Italian version provides clinicians with a rapid, feasible and sensitive tool, useful to identify different profiles of cognitive-behavioural impairment in ALS.
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http://dx.doi.org/10.1080/21678421.2016.1183679DOI Listing
October 2017

Exome-wide rare variant analysis identifies TUBA4A mutations associated with familial ALS.

Neuron 2014 Oct 22;84(2):324-31. Epub 2014 Oct 22.

Unidad de ELA, Instituto de Investigación Hospital 12 de Octubre de Madrid, SERMAS, and Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER U-723), 28041 Madrid, Spain.

Exome sequencing is an effective strategy for identifying human disease genes. However, this methodology is difficult in late-onset diseases where limited availability of DNA from informative family members prohibits comprehensive segregation analysis. To overcome this limitation, we performed an exome-wide rare variant burden analysis of 363 index cases with familial ALS (FALS). The results revealed an excess of patient variants within TUBA4A, the gene encoding the Tubulin, Alpha 4A protein. Analysis of a further 272 FALS cases and 5,510 internal controls confirmed the overrepresentation as statistically significant and replicable. Functional analyses revealed that TUBA4A mutants destabilize the microtubule network, diminishing its repolymerization capability. These results further emphasize the role of cytoskeletal defects in ALS and demonstrate the power of gene-based rare variant analyses in situations where causal genes cannot be identified through traditional segregation analysis.
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http://dx.doi.org/10.1016/j.neuron.2014.09.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4521390PMC
October 2014

A blinded international study on the reliability of genetic testing for GGGGCC-repeat expansions in C9orf72 reveals marked differences in results among 14 laboratories.

J Med Genet 2014 Jun 4;51(6):419-24. Epub 2014 Apr 4.

Oxford Medical Genetics Laboratories, Churchill Hospital, Oxford, England.

Background: The GGGGCC-repeat expansion in C9orf72 is the most frequent mutation found in patients with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Most of the studies on C9orf72 have relied on repeat-primed PCR (RP-PCR) methods for detection of the expansions. To investigate the inherent limitations of this technique, we compared methods and results of 14 laboratories.

Methods: The 14 laboratories genotyped DNA from 78 individuals (diagnosed with ALS or FTD) in a blinded fashion. Eleven laboratories used a combination of amplicon-length analysis and RP-PCR, whereas three laboratories used RP-PCR alone; Southern blotting techniques were used as a reference.

Results: Using PCR-based techniques, 5 of the 14 laboratories got results in full accordance with the Southern blotting results. Only 50 of the 78 DNA samples got the same genotype result in all 14 laboratories. There was a high degree of false positive and false negative results, and at least one sample could not be genotyped at all in 9 of the 14 laboratories. The mean sensitivity of a combination of amplicon-length analysis and RP-PCR was 95.0% (73.9-100%), and the mean specificity was 98.0% (87.5-100%). Overall, a sensitivity and specificity of more than 95% was observed in only seven laboratories.

Conclusions: Because of the wide range seen in genotyping results, we recommend using a combination of amplicon-length analysis and RP-PCR as a minimum in a research setting. We propose that Southern blotting techniques should be the gold standard, and be made obligatory in a clinical diagnostic setting.
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http://dx.doi.org/10.1136/jmedgenet-2014-102360DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4033024PMC
June 2014

A genome-wide association meta-analysis identifies a novel locus at 17q11.2 associated with sporadic amyotrophic lateral sclerosis.

Hum Mol Genet 2014 Apr 20;23(8):2220-31. Epub 2013 Nov 20.

Department of Neuroscience.

Identification of mutations at familial loci for amyotrophic lateral sclerosis (ALS) has provided novel insights into the aetiology of this rapidly progressing fatal neurodegenerative disease. However, genome-wide association studies (GWAS) of the more common (∼90%) sporadic form have been less successful with the exception of the replicated locus at 9p21.2. To identify new loci associated with disease susceptibility, we have established the largest association study in ALS to date and undertaken a GWAS meta-analytical study combining 3959 newly genotyped Italian individuals (1982 cases and 1977 controls) collected by SLAGEN (Italian Consortium for the Genetics of ALS) together with samples from Netherlands, USA, UK, Sweden, Belgium, France, Ireland and Italy collected by ALSGEN (the International Consortium on Amyotrophic Lateral Sclerosis Genetics). We analysed a total of 13 225 individuals, 6100 cases and 7125 controls for almost 7 million single-nucleotide polymorphisms (SNPs). We identified a novel locus with genome-wide significance at 17q11.2 (rs34517613 with P = 1.11 × 10(-8); OR 0.82) that was validated when combined with genotype data from a replication cohort (P = 8.62 × 10(-9); OR 0.833) of 4656 individuals. Furthermore, we confirmed the previously reported association at 9p21.2 (rs3849943 with P = 7.69 × 10(-9); OR 1.16). Finally, we estimated the contribution of common variation to heritability of sporadic ALS as ∼12% using a linear mixed model accounting for all SNPs. Our results provide an insight into the genetic structure of sporadic ALS, confirming that common variation contributes to risk and that sufficiently powered studies can identify novel susceptibility loci.
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http://dx.doi.org/10.1093/hmg/ddt587DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3959809PMC
April 2014

C9orf72 repeat expansions are restricted to the ALS-FTD spectrum.

Neurobiol Aging 2014 Apr 2;35(4):936.e13-7. Epub 2013 Oct 2.

Department of Neurology and Laboratory of Neuroscience, Istituto di Ricovero e Cura a Carattere Scientifico Istituto Auxologico Italiano, Milan, Italy; Department of Pathophysiology and Transplantation, Dino Ferrari Center, Università degli Studi di Milano, Milan, Italy.

Expansion of a GGGGCC repeat (RE) in the C9orf72 gene has been recently reported as the main genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Given the growing evidence of genetic and clinicopathologic overlap among ALS, FTD, and other neurodegenerative diseases, we investigated the occurrence of RE in a subset of 9 patients with ALS-plus syndromes, including Parkinson's disease (PD), progressive supranuclear palsy (PSP), corticobasal syndrome (CBS), and multiple system atrophy. We identified RE in 2 ALS-plus individuals (22.2%) displaying PSP and CBS features. On the basis of this finding, we extended our analysis to a cohort composed of 190 PD, 103 CBS, 107 PSP, and 177 Alzheimer's disease cases. We did not identify any RE in these patients, indicating that C9orf72 is in all probability not involved in the pathogenesis of these disorders. However, the high frequency of C9orf72 RE in patients with ALS-plus syndromes suggests that, similar to ALS-FTD patients, individuals with combined motor neuron and extrapyramidal features should be screened for RE, independent of their family history.
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http://dx.doi.org/10.1016/j.neurobiolaging.2013.09.037DOI Listing
April 2014

Analysis of hnRNPA1, A2/B1, and A3 genes in patients with amyotrophic lateral sclerosis.

Neurobiol Aging 2013 Nov 2;34(11):2695.e11-2. Epub 2013 Jul 2.

Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Via Zucchi 18, 20095 Cusano Milanino, Milan, Italy.

Mutations in the prion-like domain (PrLD) of hnRNPA1 and A2/B1 genes were recently identified in 2 families with inclusion body myopathy associated with Paget disease of bone, frontotemporal dementia (FTD), and amyotrophic lateral sclerosis, and in ALS patients. These mutations were shown to increase the propensity of hnRNPA1 and A2/B1 proteins, which are TDP-43-binding partners, to self-aggregate. hnRNPA3 protein contains a similar PrLD and was recently described in the p62-positive/TDP-43-negative inclusions in affected tissues of C9orf72-mutated ALS/FTD patients. We screened hnRNPA1, A2/B1, and A3 genes in a cohort of 113 familial ALS (FALS) individuals without mutations in other known ALS-causative genes. We extended our analysis to 108 FALS with mutations in other ALS-associated genes and to 622 sporadic cases by screening specifically the PrLDs of hnRNPA1, A2/B1, and A3. We failed to find variants in each cohort. Our results suggest that mutations in hnRNPA1, A2/B1, and A3 genes are a rare finding in ALS.
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http://dx.doi.org/10.1016/j.neurobiolaging.2013.05.025DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6591723PMC
November 2013

Screening of the PFN1 gene in sporadic amyotrophic lateral sclerosis and in frontotemporal dementia.

Neurobiol Aging 2013 May 11;34(5):1517.e9-10. Epub 2012 Oct 11.

Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy.

Mutations in the profilin 1 (PFN1) gene, encoding a protein regulating filamentous actin growth through its binding to monomeric G-actin, have been recently identified in familial amyotrophic lateral sclerosis (ALS). Functional studies performed on ALS-associated PFN1 mutants demonstrated aggregation propensity, alterations in growth cone, and cytoskeletal dynamics. Previous screening of PFN1 gene in sporadic ALS (SALS) cases led to the identification of the p.E117G mutation, which is likely to represent a less pathogenic variant according to both frequency data in control subjects and cases, and functional experiments. To determine the effective contribution of PFN1 mutations in SALS, we analyzed a large cohort of 1168 Italian SALS patients and also included 203 frontotemporal dementia (FTD) cases because of the great overlap between these 2 neurodegenerative diseases. We detected the p.E117G variant in 1 SALS patient and the novel synonymous change p.G15G in another patient, but none in a panel of 1512 control subjects. Our results suggest that PFN1 mutations in sporadic ALS and in FTD are rare, at least in the Italian population.
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http://dx.doi.org/10.1016/j.neurobiolaging.2012.09.016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3548975PMC
May 2013

C9ORF72 repeat expansion in a large Italian ALS cohort: evidence of a founder effect.

Neurobiol Aging 2012 Oct 4;33(10):2528.e7-14. Epub 2012 Jul 4.

Department of Neurology and Laboratory of Neuroscience, IRCCS Istituto Auxologico Italiano, Milan, Italy.

A hexanucleotide repeat expansion (RE) in C9ORF72 gene was recently reported as the main cause of amyotrophic lateral sclerosis (ALS) and cases with frontotemporal dementia. We screened C9ORF72 in a large cohort of 259 familial ALS, 1275 sporadic ALS, and 862 control individuals of Italian descent. We found RE in 23.9% familial ALS, 5.1% sporadic ALS, and 0.2% controls. Two cases carried the RE together with mutations in other ALS-associated genes. The phenotype of RE carriers was characterized by bulbar-onset, shorter survival, and association with cognitive and behavioral impairment. Extrapyramidal and cerebellar signs were also observed in few patients. Genotype data revealed that 95% of RE carriers shared a restricted 10-single nucleotide polymorphism haplotype within the previously reported 20-single nucleotide polymorphism risk haplotype, detectable in only 27% of nonexpanded ALS cases and in 28% of controls, suggesting a common founder with cohorts of North European ancestry. Although C9ORF72 RE segregates with disease, the identification of RE both in controls and in patients carrying additional pathogenic mutations suggests that penetrance and phenotypic expression of C9ORF72 RE may depend on additional genetic risk factors.
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http://dx.doi.org/10.1016/j.neurobiolaging.2012.06.008DOI Listing
October 2012
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