3335 results for "*geneti*"

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• Allele Balance Bias Identifies Systematic Genotyping Errors and False Disease Associations

  In recent years, Next Generation Sequencing (NGS) has become a cornerstone of clinical genetics and diagnostics. Many clinical applications require high precision, especially if rare events such as somatic mutations in cancer or genetic variants causing rare diseases need to be identified. Although random sequencing errors can be modeled statistically and deep sequencing minimizes their impact, systematic errors remain a problem even at high depth of coverage. Understanding their source is crucial to increase precision of clinical NGS applications. In this work, we studied the relation between recurrent biases in allele balance (AB), systematic errors and false positive variant calls across a large cohort of human samples analyzed by whole exome sequencing (WES). We have modeled the allele balance distribution for biallelic genotypes in 987 WES samples in order to identify positions recurrently deviating significantly from the expectation, a phenomenon we termed allele balance bias (ABB). Furthermore, we have developed a genotype callability score based on ABB for all positions of the human exome, which detects false positive variant calls that passed state-of-the-art filters. Finally, we demonstrate the use of ABB for detection of false associations proposed by rare variant association studies (RVAS).

  Study EGAS00001003027

• The evolutionary history of human colitis-associated colorectal cancer

  Inflammatory bowel disease confers an increased lifetime risk of developing colorectal cancer (CRC), and colitis-associated CRC (CA-CRC) is molecularly distinct from sporadic CRC (S-CRC). Here we have dissected the evolutionary history of CA-CRC using multi-region sequencing. Exome sequencing was performed on fresh-frozen multiple regions of carcinoma, adjacent non-cancerous mucosa and blood from 12 CA-CRC patients (n=55 exomes), and key variants were validated with orthogonal methods. Genome-wide copy number profiling was performed using SNP arrays and low-pass whole genome sequencing on archival non-dysplastic mucosa (n=9), low-grade dysplasia (LGD, n=30), high-grade dysplasia (HGD, n=13), mixed LGD/HGD (n=7) and CA-CRC (n=19). Phylogenetic trees were reconstructed, and evolutionary analysis used to reveal the temporal sequence of events leading to CA-CRC. 10/12 tumors were microsatellite stable with a median mutation burden of 3.0 single nucleotide alterations (SNAs) per Mb, around 20% higher than S-CRC (2.5 SNAs/Mb), and consistent with elevated aging-associated mutational processes. Non-dysplastic mucosa had considerable mutation burden (median 47 SNAs), including mutations shared with the neighboring CA-CRC, indicating a pre-cancer mutational field. CA-CRCs were often near-triploid (42%) or near-tetraploid (21%) and phylogenetic analysis revealed that copy number alterations (CNAs) began to accrue in non-dysplastic bowel, but the LGD/HGD transition often involved a punctuated catastrophic CNA increase.

  Study EGAS00001003028

• WES analysis in identifying additive genetic factors that may contribute to the occurrence of moyamoya in neurofibromatosis type 1

  Moyamoya is a progressive cerebral vasculopathy, for which genetic susceptibility factors were mainly identified in Asian populations. When associated with other medical conditions, such as neurofibromatosis type 1 (NF1), this vasculopathy is frequently reported as Moyamoya syndrome (MMS). Intriguingly, most cases of MMS-complicated NF1 have been described in Caucasians, inverting the population ratio for moyamoya vasculopathy observed in Asians, despite NF1 prevalence being constant worldwide. This study aims to investigate whether, among Caucasians, additive genetic factors may contribute to the occurrence of MMS in NF1. WES analysis has been carried out on an Italian family with co-occurrence of NF1 and MMS, as well as other cerebral vasculopathies.

  Study EGAS00001003053

• Indonesian Genome Diversity Project

  Indonesia, the world’s fourth largest country by population, comprises an archipelago of about 900 permanently inhabited islands in tropical Asia, and hosts an astonishing array of human diversity that remains largely underrepresented in modern biological surveys. The region is unique for its key role in both the early and recent evolution of Homo outside of Africa. It has one of the first traces of anatomically modern humans in Eurasia, and was the focus of extensive interaction between archaic hominins and humans – both in the likely co-existence of H. floresiensis with modern humans, and in the introgression of Denisovans into the ancestors of its present inhabitants. More recently, Indonesia was a center of the spread of Neolithic culture by Austronesian speakers. Advancing maritime technologies allowed farming populations to treat this region as a springboard to reach oceanic islands as remote as Madagascar, Hawaii, Easter Island and New Zealand. Here we present complete human genomes from healthy individuals from multiple key islands in Indonesia and Papua. The genomes were sequenced to high depth (30x). The purpose of this dataset is to address different questions of human evolution in Island Southeast Asia and beyond, including early settlement of the area by anatomically modern humans, population structure, genetic admixture and adaptation, and contacts with archaic hominins. We employed a sampling strategy to capture a broad range of diversity across the region incorporating an average of 12 samples from each of 14 islands spanning Indonesia and Papua, from Sumatra in the west to New Britain in the east. Genomes from this dataset form part of an ongoing project to describe and understand human evolutionary history in Island Southeast Asia and Eurasia in general.

  Study EGAS00001003054

• The evolutionary landscape of colorectal tumorigenesis

  The genetic events that cause colorectal adenomas to progress to carcinomas remain largely undetermined. Using multi-region genome/exome sequencing of 24 benign and malignant colorectal tumours, we probe the evolutionary fitness landscape occupied by these neoplasms. Unlike carcinomas, advanced adenomas frequently harbour sub-clonal driver mutations, hence lack selective sweeps, and have relatively high genetic heterogeneity. Carcinomas are distinguished from adenomas not by nucleotide-level mutations (drivers or burden), but by widespread aneusomies that are usually clonal and often accrue in a “punctuated” fashion. Adenomas evolve across an undulating fitness landscape, whereas carcinomas occupy a sharper fitness peak, probably owing to stabilising selection.

  Study EGAS00001003066

• SLC9A3R1 variant associated with age-related hearing loss

  Age-related hearing loss (ARHL) is the most common sensory impairment in the elderly affecting millions of people worldwide. To shed light on the genetics of ARHL, a large cohort of 464 Italian patients has been deeply analyzed at clinical and molecular level. A missense variant in SLC9A3R1 has been identified in two unrelated ARHL patients. A knock-in zebrafish model confirmed the pathogenic effect of the variant.

  Study EGAS00001003072

• Exome sequencing in bipolar disorder families

  Bipolar disorder (BD) is a major psychiatric disorder affecting around 1% of the global population. BD is characterized by recurrent manic and depressive episodes, and has an estimated heritability of around 70% Research has identified the first BD susceptibility genes. However, the underlying pathways and regulatory networks remain largely unknown. Since research has shown that the cumulative impact of common alleles with small effect appears to explain only around 25-38% of the phenotypic variance for BD, rare variants of high penetrance may also contribute to BD risk. The present study investigated the role of rare, nonsynonymous, and potentially functional variants via whole exome sequencing in 15 BD cases from two large, multiply affected families from Cuba. The high prevalence of BD in these pedigrees renders them promising in terms of the identification of genetic risk variants with large effect sizes. In addition, SNP array data were used to calculate polygenic risk scores for affected and unaffected family members. After correction for multiple testing, polygenic risk scores for common, BD-associated genetic variants were not significantly higher in BD cases than in healthy relatives. Exome sequencing identified a total of 17 rare and potentially damaging variants in 17 genes. The identified variants were shared by all investigated BD cases in the respective pedigree. The most promising variant was located in the gene SERPING1 (p.L349F), which has been reported as a genome-wide significant risk gene for schizophrenia. A further promising variant was located in CAPN2, which has been implicated in synaptic plasticity. The present data suggest novel candidate genes for BD susceptibility, and may facilitate the discovery of disease-relevant pathways and regulatory networks.

  Study EGAS00001003085

• Heritable pulmonary arterial hypertension in a large Iberian family

  Data from a study of a large Iberian family (n=65 subjects, 5 generations) affected by pulmonary arterial hypertension (PAH) and segregating with the BMPR2 missense mutation p.Arg491Gln (rs137852749, c.1472G>A). PAH is a rare disease characterized by an abnormal rise in mean pulmonary arterial pressure (> or equal to 25 mmHg at rest), which, in turn, leads to a progressive increase in pulmonary vascular resistance and ultimately to death, due to right ventricular failure. Heritable PAH has an overall prevalence below 1 case per million adults and is defined by either the presence of a known genetic defect linked to the disease or a positive family history. Heritable PAH is inherited as an autosomal dominant disease. However, not all BMPR2 mutation carriers develop the disease, highlighting the presence of reduced penetrance. In this family, there are 22 mutation carriers from which 8 were diagnosed with heritable PAH and the other 14 were healthy at the time of examination.

  Study EGAS00001003123

• Histone acetylome-wide association study on tuberculosis infection

  Epigenetic mechanisms are thought to play an important role in the pathogenesis of infectious diseases. Here, we describe the first histone acetylome-wide association study (HAWAS) of an infectious disease, based on genome-wide H3K27 acetylation profiling of peripheral granulocytes and monocytes from subjects with active Mycobacterium tuberculosis (Mtb) infection and healthy controls (135 ChIP-seq datasets).

  Study EGAS00001003118

• Whole-exome sequencing of extranodal NK/T cell lymphoma

  Extranodal NK/T cell lymphoma (ENKTCL) is an aggressive Epstein-Barr virus-associated T/NK neoplasm that predominantly affects Asians. To explore the causative somatic events, we conducted a comprehensive genetic analysis of 19 ENKTCL patients including whole-exome sequencing (N = 16). Commonly deregulated gene pathways in ENKTCL included epigenetic modifiers followed by human leukocyte antigen (HLA) and related genes and JAK-STAT pathway.

  Study EGAS00001004357