Project description:Clinical whole genome sequencing has enabled the discovery of potentially pathogenic noncoding variants in the genomes of rare disease patients with a prior history of negative genetic testing. However, interpreting the functional consequences of noncoding variants and distinguishing those that contribute to disease etiology remains a challenge. Here we address this challenge by experimentally profiling the functional consequences of rare noncoding variants detected in a cohort of undiagnosed rare disease patients at scale using a massively parallel reporter assay. We demonstrate that this approach successfully identifies rare noncoding variants that alter the regulatory capacity of genomic sequences. In addition, we describe an integrative analysis that utilizes genomic features alongside patient clinical data to further prioritize candidate variants with an increased likelihood of pathogenicity. This works represents an important step towards establishing a framework for the clinical interpretation of noncoding variants.
Project description:Changes in the amino acid sequences of proteins cause thousands of human genetic diseases. However, only a subset of variants in any protein is typically pathogenic, with variants having a diversity of molecular consequences. Determining which of the thousands of possible variants in any protein have similar molecular effects is very challenging, but crucial for identifying pathogenic variants, determining disease mechanisms, understanding clinical phenotypic variation, and developing targeted therapeutics. Here we present a general method to classify variants by their molecular effects that we term intramolecular genetic interaction profiling. The approach relies on the principle that variants with similar molecular consequences have similar genetic interactions with other variants in the same protein. These intramolecular genetic interactions are straightforward to quantify for any protein with a selectable function. We apply intramolecular genetic interaction profiling to amyloid beta, the protein that aggregates in Alzheimer’s disease (AD) and is mutated in familial AD (fAD). Genetic interactions identify two classes of gain-of-function variants, with all known familial Alzheimer’s disease variants having very similar genetic interaction profiles, consistent with a common gain-of-function mechanism leading to pathology. We believe that intramolecular genetic interaction profiling is a powerful approach for classifying variants in disease genes that will empower rare variant association studies and the discovery of disease mechanisms.
Project description:<p>We investigated the cumulative contribution of rare, exonic genetic variants on the concentration of 1,487 metabolites and 53,714 metabolite ratios in urine by performing gene-based tests based on 226,233 variants from up to 4,864 participants of the German Chronic Kidney Disease (GCKD) study. There were 128 significant associations (53 metabolite-gene and 75 metabolite ratio-gene pairs) involving 30 unique genes, 16 of which are known to underlie recessively inherited inborn errors of metabolism (IEMs). Across the 30 genes, 47% of individuals carried at least one rare missense, stop or splice variant. The 30 genes were strongly enriched for shared high expression in liver and kidney (OR=65, p-FDR=3e-7), with hepatocytes and proximal tubule cells as driving cell types. Use of whole-exome sequencing data in the UK Biobank allowed for linking genes to diseases that could plausibly be explained by the identified metabolites. In silico constraint-based modeling of knockouts of the implicated genes in a virtual whole-body, organ-resolved metabolic human correctly predicted the observed direction of metabolite changes in urine and blood, highlighting the potential of linking population genetics to modeling to validate associations and to predict metabolic consequences of yet unknown IEMs. Our study extends the map of genes influencing urine metabolite concentrations, reveals metabolic processes and connected health outcomes, and implicates novel candidate variants and genes for IEMs.</p><p><br></p><p>Further links;</p><p><a href='https://www.gckd.org/' rel='noopener noreferrer' target='_blank'>German Chronic Kidney Disease (GCKD)</a></p>
Project description:Mutations that cause exon skipping can have severe consequences on gene function and cause disease. Here we explore how human genetic variation affects exon recognition by developing a Multiplexed Functional Assay of Splicing using Sort-seq (MFASS). We assayed 27,733 variants in the Exome Aggregation Consortium (ExAC) within or adjacent to 2,198 human exons in the MFASS minigene reporter, and found that 3.8% (1,050) of variants, most of which are extremely rare, led to large-effect splice-disrupting variants (SDVs). Importantly, we find that 83% of SDVs are located outside of canonical splice sites, are distributed evenly across distinct exonic and intronic regions, and are difficult to predict a priori. Our results indicate extant, rare genetic variants, even outside the context of disease, can have large functional effects at appreciable rates, and that MFASS enables their empirical assessment for large-effect splicing defects at scale.
Project description:The identification of the genetic risk factors in patients with isolated cleft palate by whole genome sequencing analysis. Pathogenic or likely pathogenic variants were discovered in genes associated with CP (TBX22, COL2A1, FBN1, PCGF2, and KMT2D) in five patients; hence, rare disease variants were identified in 17% of patients with non-syndromic isolated CP. Our results are relevant to routine genetic counselling practice and genetic testing recommendations.
Project description:Background & Aims: Most inflammatory bowel diseases (IBDs) are classic polygenic disorders represented by common alleles. However, multiple determinants of very early-onset IBD characterized by a more extensive disease course remain largely unknown. The present study aimed to define the genetic architecture of pediatric and adult-onset IBDs in the Polish population. Results: Of 82 SNPs validated/replicated for association with IBD, a novel BRD2 (rs1049526) association was found in both pediatric (OR= 2.35) and adult (OR= 2.66) patients. Thirty SNPs were shared between pediatric and adult patients; 22 and 30 were unique to adult-onset and pediatric-onset IBD, respectively. WES identified numerous rare/infrequent, potentially deleterious variants in IBD-associated or innate immunity-associated genes. Both groups of variants were over-represented in affected children. Two highly deleterious homozygous variants, HLA-DRB1 c.565_566insC and NCF4 p.Arg8Trp, were found in two affected children, and WAS p.Glu131Lys was found in one child and one adult patient. Conclusions: Our GWAS revealed differences in the polygenic architecture of pediatric- and adult-onset IBD. A significant accumulation of rare/low frequency deleterious variants in affected children suggests a contribution by yet unexplained genetic components.
Project description:Obesity is considered a multifactorial disorder with high heritability (50-75%), probably higher in early-onset and severe cases. Although rare monogenic forms and several genes and regions of susceptibility, including CNVs, have been defined, the genetic causes underlying the disease still remain largely unknown. We aimed to identify novel genetic and genomic abnormalities in a cohort of Spanish children with severe non-syndromic early-onset obesity (EOO). We obtained molecular karyotypes of 157 children with EOO. Large and rare CNVs were validated and segregated in the family. A higher burden of duplication-type CNVs was detected in EOO patients versus controls (OR=1.85, p-value=0.008).
Project description:Obesity is a major risk factor for many common diseases and has a significant heritable component. While clinical and large-scale population studies have identified several genes harbouring rare alleles with large effects on obesity risk, there are likely many unknown genes with highly penetrant effects remaining. To this end, we performed whole exome-sequence analyses for adult body mass index (BMI) in up to 587,027 individuals. We identified rare, loss of function variants in two genes – BSN and APBA1 – with effects on BMI substantially larger than well-established obesity genes such as MC4R. One in ~6500 individuals carry a heterozygous protein truncating variant (PTV) in BSN, which confers a 6.6, 3.7 and 3-fold higher risk of severe obesity (BMI >40kg/m2), non-alcoholic fatty liver disease and type 2 diabetes, respectively. Rare PTVs in BSN were found in three patients with severe early onset obesity, but in contrast to most other obesity-related genes, rare variants in BSN and APBA1 were not associated with normal variation in childhood adiposity. Furthermore, BSN PTVs magnified the influence of common genetic variants associated with BMI, with a common polygenic score exhibiting an effect on BMI twice as large in BSN PTV carriers than non-carriers. Finally, we explored the plasma proteomic signatures of BSN PTV carriers as well as the functional consequences of BSN deletion in human iPSC-derived hypothalamic neurons. These approaches highlighted a network of differentially expressed genes that were collectively enriched for genomic regions associated with BMI, and suggest emerging roles for neurodevelopment, neurogenesis, and altered neuronal oxidative phosphorylation in the etiology of obesity.
Project description:Systemic lupus erythematosus (SLE) is the prototypic systemic autoimmune disease. It is thought that many common variant gene loci of weak effect act additively to predispose to common autoimmune diseases, while the contribution of rare variants remains unclear. Here we describe that rare coding variants in lupus-risk genes are present in most SLE patients and healthy controls. We demonstrate the functional consequences of rare and low frequency missense variants in the interacting proteins BLK and BANK, which are present alone, or in combination, in a substantial proportion of lupus patients. The rare variant found in patients, but not those found exclusively in controls, impair suppression of IRF and type-I IFN in human B cell lines and increase pathogenic lymphocytes in lupus-prone mice. Thus, rare gene variants are common in SLE and likely contribute to genetic risk.