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• High MAPK Activity Leading to Reduced WNT Signaling Drives Metastasis in Colorectal Cancer

  Colorectal cancer, a leading cause of cancer-related mortality due to distant metastases, is driven by activating mutations in the Wnt and MAPK pathways. Understanding the interplay between these crucial pathways during metastatic progression is essential for developing effective treatments. Here we developed an immunocompetent mouse model of metastatic colorectal cancer using in vivo orthotopic passaging. We demonstrate that highly metastatic tumor cells exhibit chromosomal amplifications in MAPK pathway genes, leading to increased MAPK activity, which in turn suppresses Wnt-associated transcriptional programs, including stem cell-associated genes. Inhibiting mutant KrasG12D effectively reversed this metastatic transcriptional state, reducing MAPK-driven gene expression and restoring Wnt activity. Notably, this treatment significantly curtailed lung metastases and reduced liver metastases during early seeding stages. Analysis of CRC patient data revealed that high MAPK activity and the associated metastatic gene signature correlated with poorer survival outcomes. These findings underscore that the plasticity of metastasis-initiating cells in CRC arises from the opposing roles of MAPK and Wnt signaling, despite their synergistic importance in colon tumor initiation.

  Study EGAS50000001231

• RTEL1 mutation as a modifier of Dyskeratosis Congenita in a family with a Telomerase RNA (hTR) template mutation and variant telomeric repeats

  Vertebrate telomeres, the sequences protecting the end of linear chromosomes, are composed of conserved hexameric GGTTAG repeats. Here we present a C50>A telomerase RNA template mutation that results in the incorporation of the variant telomeric repeat GTTTAG in a family with dyskeratosis congenita primarily presenting as idiopathic pulmonary fibrosis. The mutant telomerase is characterized by decreased processivity in direct telomerase activity assays and in vivo based on data from Illumina next-generation whole genome sequencing and Oxford Nanopore Technologies long-read telomere sequencing. The latter provided positional mutant repeat information that revealed the inheritance and maintenance of proximal mutant repeats in individuals who did not inherit the template mutation. Additionally, we describe an RTEL1 nonsense mutation that is associated with very short telomeres in progeny harboring wild-type telomerase and inherited mutant telomeric repeats in the absence of overt clinical phenotypes. In contrast, co-inheritance of the RTEL1 nonsense and TERC r.C50>A mutations coincided with severe early-onset DC phenotypes in two individuals.

  Study EGAS50000001644

• Fragmentomics Uncover Non-Mutational HRD Features

  Homologous recombination deficiency (HRD) is a key biomarker in prostate cancer (PCa), predicting response to PARP inhibitors and platinum-based therapies. However, current diagnostics often rely solely on BRCA1/2 mutations or genomic scars, missing cases driven by other mechanisms. Tissue-based testing is further limited by tumor heterogeneity and biopsy challenges in metastatic bone disease. Here, we applied a comprehensive multimodal approach to assess HRD in 106 advanced PCa patients using circulating tumor DNA (ctDNA). This included targeted sequencing of homologous recombination repair (HRR) genes, low-pass WGS for genomic instability (sHRD), WES for mutational signatures, and cfDNA fragmentomics and chromatin accessibility profiling. BRCA2 was the most frequently altered gene, often co-occurring with PTEN loss. High sHRD scores correlated with BRCA2/RB1 loss, somatic copy number alterations, and poor survival. HRD tumors showed enrichment of SBS3/ID6 signatures, altered fragment lengths, and reduced accessibility at zinc finger transcription factor sites. These results support ctDNA-based multimodal profiling as a non-invasive strategy for HRD detection and stratification.

  Study EGAS00001008190

• DCIS fresh frozen fragmentomics dataset

  Ductal carcinoma in situ (DCIS) is a non-obligate precursor lesion of breast cancer (BC). Often detected by mammography, most cases are managed through surgical and/or radiotherapy approaches. Today, it is not possible to predict which patients will progress to invasive disease. Here, we evaluated high-depth whole-genome sequenced (WGS) DCIS, enriched for highgrade clinical lesions, to understand whether deep WGS could reveal biological insights and/or personalized therapeutic vulnerabilities that may be targetable. We find genomic locations that are likely susceptible to producing the initiating lesion for structural variations (SVs) prone to subsequent evolution, termed SHOREs (Susceptibility HOtspots for Rearrangements and ongoing Evolution). We additionally highlight individualized therapeutic potential that would otherwise not be appreciable without WGS. We posit that holistic WGS profiling could offer a more precise stratification approach, discerning higher-risk cases for prospective clinical studies on personalized therapies, from truly low-risk cases suitable for active monitoring. To substantiate our WGS findings, we also performed RNAseq on the same samples, this EGA study contains the RNAseq data.

  Study EGAS50000001475

• Data upcycling, powered by EGA

  In 2012 a collaborative effort headed by the teams of Carlos Caldas in Cambridge, UK and Samuel Aparicio, Canada, produced a pivotal study aimed at defining the mutational landscape of breast cancer. They gathered a collection of over 2000 breast cancer samples (METABRIC) associated with long-term clinical follow-up. They delineated an array of inherited and somatically acquired genetic variants and associated them to gene expression. This led to the identification of putative cancer-driving events and improved stratification of breast cancer patients. The study elicited huge attention and was tackled as herculean effort by fellow researchers. Cristina Curtis and her colleagues deposited the data in the EGA archive (EGAS00000000083). What they probably could not foresee is that their data would be reused more than 100 times, becoming one of the most downloaded datasets at EGA. In 2015, Frederik S. Varn and colleagues accessed the above-mentioned data from the New Hampshire, USA, to correlate it to transcriptional programs of hematopoietic cells infiltrated in breast tumours and found that those can influence patients' prognosis. Their findings, published in Nature Communications, improved the understanding of the interplay between immune system and cancer. Again, in 2017 the dataset was downloaded by an Italian/Polish collaboration and used to corroborate their mechanistic study that demonstrate how a long non-coding RNA (lncRNA) is aberrantly localized into the chromatin, where it modulates oncogenic isoforms expression, thus contributing to breast cancer. To date, the METABRIC dataset has been reused to contribute to 147 publications. Its impact on breast cancer research is incalculable, and it even spread beyond that, with recent contributions to the understanding of pan-cancer mechanisms and features. Some of the publications are translating into improvements in diagnosis and treatment of different types of breast cancer. This is just an example of how data upcycling can amplify the potential of any dataset, well past the scope of its creation, the imagination of its owners and any geographical border. At EGA, we are proud to empower such fruitful worldwide cycles of knowledge, providing a platform that enables safe sharing of sensitive genetic data.

  Blog data-upcycling-powered-by-ega

• Genomic Analyses Identify Recurrent MEF2D Fusions in Acute Lymphoblastic Leukemia

  Chromosomal rearrangements are initiating events in acute lymphoblastic leukemia (ALL). Here, using RNA-sequencing (RNAseq) of 560 ALL cases, we identify rearrangements between MEF2D (myocyte enhancer factor 2D) and five genes (BCL9, CSF1R, DAZAP1, HNRNPUL1 and SS18) in 22 B progenitor ALL (B-ALL) cases with a distinct gene expression profile, the most common of which is MEF2D-BCL9. Examination of an extended cohort of 1164 B-ALL cases identified 30 cases with MEF2D rearrangements which include an additional fusion partner, FOXJ2, thus MEF2D-rearranged cases comprise 5.3% of cases lacking recurring alterations. MEF2D-rearranged ALL is characterized by a distinct immunophenotype, DNA copy number alterations at the rearrangement sites, older diagnosis age, and poor outcome. The rearrangements result in enhanced MEF2D transcriptional activity, lymphoid transformation, activation of HDAC9 expression and sensitive to histone deacetylase inhibitors treatment. Thus, MEF2D-rearranged ALL represents a distinct form of high-risk leukemia, for which new therapeutic approaches should be considered.

  Study EGAS00001001952

• Comprehensive analyses of somatic TP53 mutation in tumors with variable mutant allele frequency

  Somatic mutation of the tumor suppressor gene TP53 is reported in at least 50% of human malignancies. Most high-grade serous ovarian cancers (HGSC) have a mutant TP53 allele. Accurate detection of these mutants in heterogeneous tumor tissue is paramount as therapies emerge to target mutant p53. We used a Fluidigm Access Array™ System with Massively Parallel Sequencing (MPS) to analyze DNA extracted from 76 serous ovarian tumors. This dataset has been made available to researchers through the European Genome-phenome Archive (EGA). Herein, we present detailed analyses of this dataset using HaplotypeCaller and MuTect2 through the Broad Institute’s Genome Analysis Toolkit (GATK). We also present comparisons of the ability to detect TP53 mutation by MPS and Sanger sequencing in these tumors. We anticipate that this TP53 mutation dataset will be useful to researchers developing and testing new software to accurately determine high and low frequency variant alleles in heterogeneous aneuploid tumor tissue. Further, the analysis pipeline we present provides a valuable framework for determining somatic variants more broadly in tumor tissue.

  Study EGAS00001002200

• The genetic structure of Norway

  The aim of the present study was to describe the genetic structure of the Norwegian population using genotypes from 6369 unrelated individuals with detailed information about places of residence. Using standard single marker- and haplotype-based approaches, we report evidence of two regions with distinctive patterns of genetic variation, one in the far northeast, and another in the south of Norway, as indicated by fixation indices, haplotype sharing, homozygosity and effective population size. We detect and quantify a component of Uralic Sami ancestry that is enriched in the North. On a finer scale, we find that rates of migration have been affected by topography like mountain ridges. In the broader Scandinavian context, we detect elevated relatedness between the mid- and northern border areas towards Sweden. The main finding of this study is that despite Norway’s long maritime history and as a former Danish territory, the region closest to mainland Europe in the south appears to have been the most isolated region in Norway, highlighting the open sea as a barrier to gene flow into Norway.

  Study EGAS00001004826

• Inference of transcription factor binding from cell-free DNA enables tumor subtype prediction and early detection

  Deregulation of transcription factors (TFs) is an important driver of tumorigenesis, but non-invasive assays for assessing transcription factor activity are lacking. We Here we developed and validated a minimally invasive method for assessing TF activity based on cell-free DNA sequencing and nucleosome footprint analysis. We analyzed whole genome sequencing data for >1,000 cell-free DNA samples from cancer patients and healthy controls using a newly developed bioinformatics pipeline developed by us that infers accessibility of TF binding sites from cell-free DNA fragmentation patterns. We observe patient-specific as well as tumor-specific patterns, including accurate prediction of tumor subtypes in prostate cancer, with important clinical implications for the management of patients. Furthermore, we show that cell-free DNA TF profiling is capable of detection of early-stage colorectal carcinomas. Our approach for mapping tumor-specific transcription factor binding in vivo based on blood samples makes a key part of the noncoding genome amenable to clinical analysis.

  Study EGAS00001003206

• Uveal melanoma patient with germline MBD4 nonsense mutation

  There is currently no effective treatment for metastasised uveal melanoma (UM). Recently, it was reported that a UM patient was responsive to checkpoint inhibitor (CI) treatment, due to a high tumour mutation burden correlated with a germline loss-of-function MBD4 mutation. Here, we report on another UM patient who carried an MBD4 germline nonsense variant (p.Leu563Ter) and her tumour showed a 5-fold higher than average mutation burden. We confirmed the association between germline loss-of-function variant in MBD4 and CI response. The patient experienced stable disease (10 months) and survived two years with metastatic disease, which is twice as long as median survival. Additionally, the frequency of MBD4 loss-of-function variants in reported UM cohorts was >20 times higher than in an aggregated population genome database (P < 5x10-5), implying a potential role as UM predisposition gene. These findings provide a strong basis for the inclusion of MBD4 in screening of potential UM-prone families as well as stratification of immunotherapy.

  Study EGAS00001003362

• Study of pediatric hepatocellular carcinoma caused by bile salt export pump deficiency

  Hepatocellular carcinoma (HCC) is almost invariably associated with an underlying inflammatory state, whose direct contribution to the acquisition of critical genomic changes is unclear. We mapped the acquired genomic alterations in human and mouse HCCs induced by defects in hepatocyte biliary transporters, which expose hepatocytes to bile salts and cause the onset of chronic inflammation that develops into cancer. In both human and mouse cancer genomes we found few somatic point mutations with no impairment of cancer genes, but instead massive gene amplification and rearrangements. This genomic landscape differs greatly from that of virus- and alcohol-associated liver cancer. Copy number gains preferentially occurred at late stages of cancer development and frequently targeted the MAPK signaling pathway, and in particular direct regulators of JNK. The pharmacological inhibition of JNK retarded cancer progression in the mouse. Our study demonstrates that intrahepatic cholestasis leading to hepatocyte exposure to bile acids and inflammation promotes cancer through genomic modifications that can be clearly distinguished from those determined by other etiological factors.

  Study EGAS00001000749

• Genomes of Relapsing Neuroblastoma

  Neuroblastoma is a malignancy of the developing sympathetic nervous system that is often lethal when relapse occurs, but the molecular mechanisms behind this process are poorly defined. We here used whole-exome sequencing, mRNA expression, array CGH and DNA methylation analysis to holistically characterize 16 paired samples from neuroblastoma patients at diagnosis and relapse. The mutational burden significantly increased in relapsing tumors accompanied by altered mutational signatures and reduced subclonal heterogeneity. Global allele frequencies at relapse indicated clonal mutation selection during disease progression. Promoter methylation patterns were consistent over disease course and patient-specific. Recurrent alterations at relapse included mutations in the putative CHD5 neuroblastoma tumor suppressor, chromosome 9p losses, DOCK8 mutations, inactivating mutations in PTPN14 and a relapse-specific activity pattern for the PTPN14 target gene, YAP. Recurrent new mutations in HRAS, KRAS, DOCK8 and genes mediating cell-cell interaction in 13/16 relapse tumors also indicate disturbances in signaling pathways mediating mesenchymal transition. Our data shed first light on genetic alteration frequency, identity and evolution in neuroblastoma.

  Study EGAS00001001387

• Pilot_experiment_on_functional_genomics_in_osteoarthritis

  The aim of this work is to apply an integrated systems approach to understand the biological underpinnings of large joint (hip and knee) osteoarthritis which culminates in the need for total joint replacement (TJR). In this pilot we will assess the feasibility of the approach in the relevant tissue. We will obtain diseased and non-diseased tissue (cartilage and endochondral bone) following TJR, coupled with a blood sample, from 12 patients. We will generate genotype data on the HumanCoreExome array and will characterise the 12 pairs of diseased and non-diseased tissue samples in terms of methylation (Illumina 450k array), transcription (RNASeq) and expression (quantitative proteomics). The pilot will help assess the feasibility of isolating sufficient levels of starting material for the different approaches, and will instigate the development of analytical approaches to synthesising the resulting data. If successful, it is envisaged that we will proceed with expanding the work to 500 patients in the first year, with a target total sample size of 3,000 in the longer term. The key collaborators in this work are Mark Wilkinson (Sheffield) and Jyoti Choudhary

  Study EGAS00001001212

• Multi-omics analysis defines core genomic alterations in pheochromocytomas and paragangliomas

  Pheochromocytomas (PCC) and paragangliomas (PGL) are neural crest-derived tumors. We performed the integrated genomic analysis of a collection of PCC/PGL from the French COMETE network using SNP arrays, whole-exome sequencing, DNA methylation arrays, mRNA expression arrays and miRNA sequencing. We found that PCC/PGL are characterized by a low mutation rate, with few recurrent somatic mutations and focal copy number alterations (CNAs). In contrast, we detected recurrent broad CNAs strongly associated with known molecular groups, often leading to the biallelic inactivation of the known susceptibility genes of PCC/PGL. We also identified DNA methylation changes and miRNA expression clusters strongly associated with molecular groups. Of note, overexpression of the miRNA cluster 182/96/183 is specific of SDHB-mutated tumors and induces invasive traits, whereas silencing of the imprinted DLK1-MEG3 miRNA cluster due to a loss of heterozygosity of the 14q32.2 locus is a potential driver in a subset of sporadic tumors. This comprehensive analysis illustrates the functional interdependence between genomic and epigenomic dysregulations underlying PCC/PGL.

  Study EGAS00001000933

• Field_effect_of_healthy_and_diseased_livers

  Recent work in the Campbell group has revealed somatic mutations present in normal, non-cancerous human skin. A subset of the mutations conferred selective advantages to the host cells, leading to clonal expansions and raising the risk for future cancer development. Capturing such somatic mutations in normal tissue is important to advance our understanding about carcinogenesis and could provide prospective medical insights. In this project, our goal is to detect somatic mutations in normal (pre-cancerous) liver tissue. Using Laser Microdissection technology, we will dissect individual liver lobules from patient samples and submit these to sequencing. For each patient sample, we aim to sequence multiple lobules to characterise the mutagenic burden. Samples will be taken from patients with different liver disease aetiologies, including alcoholism and obesity, with a view on distinguishing the prevalent mutation types occurring in each disease context. We will perform targeted sequencing, initially using the WTSI cancer panel. Later we aim to use a novel bait set that captures both cancer genes as well as genes relevant to the non-cancerous samples (ie. genes implicated in hereditary disorders, immune sequences).

  Study EGAS00001002382

• BLUEPRINT DNA methylation profiles of graft donors in allogenic hematopoietic stem cell transplantation

  Allogenic hematopoietic stem cell transplantation (HSCT) is a curative treatment for many hematological conditions. Acute graft-versus-host disease (aGVHD) is a prevalent immune-mediated complication following HSCT. Current diagnostic biomarkers that correlate with aGVHD severity, progression, and therapy response in graft recipients are insufficient. We investigated whether epigenetic marks measured in peripheral blood of healthy graft donors stratify aGVHD severity in HLA-matched sibling recipients prior to HSCT. We measured genome-wide DNA methylation levels in peripheral blood of 91 HSCT donors using Illumina Infinium HumanMethylation450 BeadChips. We showed that epigenetic signatures underlying aGVHD severity in recipients correspond to immune pathways relevant to aGVHD etiology. We identified distinct DNA methylation marks in graft donors that are associated with aGVHD severity status in recipients. Together, our findings suggest that ‘epigenetic matching’ of HSCT donor-recipient pairs in a clinical setting may be used in conjunction with genetic matching to inform both donor selection and transplantation strategy, with the ultimate aim of improving patient outcome.

  Study EGAS00001001287

• Genetic history of the Swahili population

  At the dawn of the second millennium, the expansion of the Indian Ocean trading network aligned with the emergence of an outward-oriented community along the East African coast to create a cosmopolitan cultural and trading zone known as the Swahili Corridor. Based on analyses of genome-wide genotyping data in 140 individuals from coastal Kenya and the Comoros islands, along with 3,477 individuals from the Indian Ocean rim, we reconstruct historical population dynamics showing that the Swahili Corridor is largely an East Bantu genetic continuum. Within this continuity significant gene flows from the Middle East can be seen in the Swahili and Comorians at dates corresponding to the Islamization of East Africa. However the main external gene flow into insular populations of the Swahili Corridor, such as Comorian and Malagasy groups, came from Island Southeast Asia as early as the 10th century. Remarkably, our results reflect archaeological and linguistic data in suggesting that the Comoros archipelago is the oldest place of contact between Austronesian and African populations in the Swahili Corridor.

  Study EGAS00001002569

• Using human induced pluripotent stem cells (iPSC) and iPSC-derived neurons to explore cellular phenotypes associated with schizophrenia.

  Schizophrenia and major mental illness are common devastating conditions. Whilst partially effective treatments are available, none are disease-modifying. Notwithstanding important insights provided by animal models there is a need for novel models of mental illness to develop more effective therapies. A study of sporadic schizophrenia-derived human induced pluripotent stem cells (hiPS) has demonstrated a neuronal phenotype representing a powerful proof of concept of in vitro disease modeling, even for diseases with complex causation such as schizophrenia. These techniques have been used here to examine the behaviour of neural stem cells and neurons derived from fibroblasts from subjects carrying NDE1 copy number variations (CNVs) associated with increased risk of major mental illness. Using hiPS from individuals with and without disease-associated CNVs we have investigated how disease risk is conferred at a cellular and molecular level through detailed comparative studies of neural progenitor proliferation, neuronal morphology, physiology, cytoskeletal organization, synaptic function, glutamate (NMDA) receptor expression and also RNA sequencing and proteomic studies of these patient-derived cells.

  Study EGAS00001002895

• The whole blood of female volunteers and sperm from the male volunteer were used to extract genomic DNA to do whole genome sequencing. Distinguished SNPs between parental genomes were retained to analyze parental allele-specific DNA methylation and chromatin accessibility in scCOOL-seq data.

  DNA methylation, chromatin states, and their interrelationships represent critical epigenetic information, but those are largely unknown in human early embryos. Here, we apply scCOOL-seq (Chromatin Overall Omic-scale Landscape Sequencing) to generate a genome-wide map of DNA methylation and chromatin accessibility at single-cell resolution during human preimplantation development. Unlike in mice, the chromatin of paternal genome is already more open than that of maternal genome at the mid-zygote stage in humans, and this state is maintained until the 4-cell stage. After fertilization, genes with high variations in DNA methylation and those with high variations in chromatin accessibility tend to be two different sets. Furthermore, 1,797 (35%) out of 5,155 widely open chromatin regions in promoters closed when transcription activity was inhibited, indicating a feedback mechanism between transcription and open chromatin maintenance. Our work paves the way for dissecting the complex, yet highly coordinated, epigenetic reprogramming during human preimplantation development.

  Study EGAS00001002987

• Clonal expansion and epigenetic reprogramming following deletion or amplification of mutant IDH1

  IDH1 mutation is the earliest genetic alteration in low-grade gliomas (LGGs), but its role in tumor recurrence is unclear. Mutant IDH1 drives overproduction of the oncometabolite D-2-hydroxyglutarate (2HG) and a CpG island (CGI) hypermethylation phenotype (G-CIMP). To investigate the role of mutant IDH1 at recurrence, we performed a longitudinal analysis of 50 IDH1 mutant LGGs. We discovered six cases with copy number alterations (CNAs) at the IDH1 locus at recurrence. Deletion or amplification of IDH1 was followed by clonal expansion and recurrence at a higher grade. Successful cultures derived from IDH1 mutant, but not IDH1 wild-type, gliomas systematically deleted IDH1 in vitro and in vivo, further suggestive of selection against the heterozygous mutant state as tumors progress. Tumors and cultures with IDH1 CNA had decreased 2HG, maintenance of G-CIMP, and DNA methylation reprogramming outside CGI. Thus, while IDH1 mutation initiates gliomagenesis, in some patients, mutant IDH1 and 2HG are not required for later clonal expansions.

  Study EGAS00001001854

• Primary prostate Hi-C

  Prostate cancer is a heterogeneous disease whose progression is linked to genome instability. Despite large-scale tumour sequencing efforts, the impact of mutations on the genetic architecture in cancer remains ill-defined due to limited integration of genomics data across dimensions. We addressed this limitation by assessing the impact of structural variants on the chromatin states and the three-dimensional organization across benign and malignant primary prostate genomes. We find high concordance in the three-dimensional genome organization between malignant and benign prostate tissues, arguing for constraints to the three-dimensional genome of prostate tumours. Moreover, we identify structural variants as effectors of changes to focal chromatin interactions, guiding cis-regulatory element hijacking that imposes opposing expression changes on genes found at antipodes of a rearrangement. This leads to the repression of tumour suppressor gene expression and up-regulation of oncogenes, such as at the TMPRSS2-ERG and PMEPA1-ZNF156 loci. Collectively, our results argue that cis-regulatory element hijacking by structural variants overshadows large-scale topological changes to alter gene regulation and promote oncogenesis.

  Study EGAS00001005014

• Pilot_experiment_on_functional_genomics_in_osteoarthritis

  The aim of this work is to apply an integrated systems approach to understand the biological underpinnings of large joint (hip and knee) osteoarthritis which culminates in the need for total joint replacement (TJR). In this pilot we will assess the feasibility of the approach in the relevant tissue. We will obtain diseased and non-diseased tissue (cartilage and endochondral bone) following TJR, coupled with a blood sample, from 12 patients. We will generate genotype data on the HumanCoreExome array and will characterise the 12 pairs of diseased and non-diseased tissue samples in terms of methylation (Illumina 450k array), transcription (RNASeq) and expression (quantitative proteomics). The pilot will help assess the feasibility of isolating sufficient levels of starting material for the different approaches, and will instigate the development of analytical approaches to synthesising the resulting data. If successful, it is envisaged that we will proceed with expanding the work to 500 patients in the first year, with a target total sample size of 3,000 in the longer term. The key collaborators in this work are Mark Wilkinson (Sheffield) and Jyoti Choudhary

  Study EGAS00001001213

• Mutations in SPINK2 induce azoospermia

  Azoospermia, characterized by the absence of spermatozoa in the ejaculate is a common cause of male infertility with a poorly characterized etiology. Exome sequencing analysis of two azoospermic brothers allowed the identification of a homozygous splice mutation in SPINK2, encoding a serine protease inhibitor believed to target acrosin, the main sperm acrosomal protease. In accord with these findings we observed that homozygous Spink2 KO male mice had azoospermia. Moreover, despite normal fertility, heterozygous male mice had a high rate of morphologically abnormal spermatozoa and a reduced sperm motility. Further analysis demonstrated that in the absence of Spink2, protease-induced stress initiates Golgi fragmentation and prevents acrosome biogenesis leading to spermatid differentiation arrest. We also observed a deleterious effect of acrosin overexpression in HEK cells, effect that was alleviated by SPINK2 coexpression confirming its role as acrosin inhibitor. These results demonstrate that SPINK2 is necessary to neutralize proteases during their cellular transit towards the acrosome and that its deficiency induces a pathological continuum ranging from oligoasthenoteratozoospermia in heterozygotes to azoospermia in homozygotes.

  Study EGAS00001002450

• Genetic history of the Comorian populations.

  At the dawn of the second millennium, the expansion of the Indian Ocean trading network aligned with the emergence of an outward-oriented community along the East African coast to create a cosmopolitan cultural and trading zone known as the Swahili Corridor. Based on analyses of genome-wide genotyping data in 140 individuals from coastal Kenya and the Comoros islands, along with 3,477 individuals from the Indian Ocean rim, we reconstruct historical population dynamics showing that the Swahili Corridor is largely an East Bantu genetic continuum. Within this continuity significant gene flows from the Middle East can be seen in the Swahili and Comorians at dates corresponding to the Islamization of East Africa. However the main external gene flow into insular populations of the Swahili Corridor, such as Comorian and Malagasy groups, came from Island Southeast Asia as early as the 10th century. Remarkably, our results reflect archaeological and linguistic data in suggesting that the Comoros archipelago is the oldest place of contact between Austronesian and African populations in the Swahili Corridor.

  Study EGAS00001002565

• Exome sequencing demonstrates a dual origin of relapses in retinoic-acid resistant acute promyelocytic leukemia.

  Retinoic acid (RA) and arsenic target the PML/RARA driver of Acute Promyelocytic Leukemia (APL), their combination now curing over 95% patients. Here we report exome sequencing of 64 matched diagnosis/remission/relapses patients treated with historical RA/chemotherapy protocols. A first subgroup presents a high incidence of oncogenic mutations disrupting key epigenetic or transcriptional regulators (primarily WT1) or activating MAPK signaling at diagnosis. Relapses retain these cooperating oncogenes and exhibit additional oncogenic alterations and/or mutations impeding therapy response (RARA, NT5C2). The second group primarily exhibits FLT3 activation at diagnosis, which is lost upon relapse together with most other passenger mutations, implying that relapses derive from pre-leukemic PML/RARA-expressing cells that survived RA/chemotherapy. Accordingly, clonogenic activity of PML/RARA-immortalized progenitors ex vivo is only transiently affected by RA, but selectively abrogated by arsenic. Our studies stress the role of cooperating oncogenes in direct relapses and suggest that targeting pre-leukemic cells by arsenic contributes to its clinical efficacy.

  Study EGAS00001002893