Publications by authors named "Karen Mohlke"

Osteoarthritis (OA) poses a significant healthcare burden with limited treatment options. While genome-wide association studies (GWASs) have identified over 100 OA-associated loci, translating these findings into therapeutic targets remains challenging. To address this gap, we mapped gene expression, chromatin accessibility, and 3D chromatin structure in primary human articular chondrocytes in both resting and OA-mimicking conditions.

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Complete characterization of the genetic effects on gene expression is needed to elucidate tissue biology and the etiology of complex traits. In the present study, we analyzed 2,344 subcutaneous adipose tissue samples and identified 34,774 conditionally distinct expression quantitative trait locus (eQTL) signals at 18,476 genes. Over half of eQTL genes exhibited at least two eQTL signals.

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  • - The study investigates how gene regulation at non-coding regions associated with brain traits can vary based on specific contexts, particularly focusing on the Wnt pathway in human neural progenitors from 82 donors.
  • - Researchers found that certain genetic variants linked to brain structures and neuropsychiatric disorders were more prevalent in regions responsive to Wnt activation, indicating context-dependent regulatory effects.
  • - Activation of the Wnt pathway significantly improved the detection of genetic influences on gene regulation and revealed new regulatory elements, suggesting that these genetic variants play critical roles in shaping adult brain traits and behaviors during neurodevelopment.
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  • Genome-wide association studies have found numerous genetic loci linked to glycemic traits, but connecting these loci to specific genes and biological pathways remains a challenge.
  • Researchers conducted meta-analyses of exome-array studies across four glycemic traits, analyzing data from over 144,000 participants, which led to the identification of coding variant associations in more than 60 genes.
  • The study revealed significant pathways related to insulin secretion, zinc transport, and fatty acid metabolism, enhancing understanding of glycemic regulation and making data available for further research.
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Understanding the molecular mechanisms of complex traits is essential for developing targeted interventions. We analyzed liver expression quantitative-trait locus (eQTL) meta-analysis data on 1,183 participants to identify conditionally distinct signals. We found 9,013 eQTL signals for 6,564 genes; 23% of eGenes had two signals, and 6% had three or more signals.

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Osteoarthritis (OA) poses a significant healthcare burden with limited treatment options. While genome-wide association studies (GWAS) have identified over 100 OA-associated loci, translating these findings into therapeutic targets remains challenging. Integrating expression quantitative trait loci (eQTL), 3D chromatin structure, and other genomic approaches with OA GWAS data offers a promising approach to elucidate disease mechanisms; however, comprehensive eQTL maps in OA-relevant tissues and conditions remain scarce.

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Genome-wide association studies (GWAS) have identified numerous body mass index (BMI) loci. However, most underlying mechanisms from risk locus to BMI remain unknown. Leveraging omics data through integrative analyses could provide more comprehensive views of biological pathways on BMI.

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Vertebrates transport hydrophobic triglycerides through the circulatory system by packaging them within amphipathic particles called Triglyceride-Rich Lipoproteins. Yet, it remains largely unknown how triglycerides are loaded onto these particles. Mutations in Phospholipase A2 group 12B (PLA2G12B) are known to disrupt lipoprotein homeostasis, but its mechanistic role in this process remains unclear.

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  • Type 2 diabetes (T2D) is a complex disease influenced by various genetic factors and molecular mechanisms that vary by cell type and ancestry.
  • In a large study involving over 2.5 million individuals, researchers identified 1,289 significant genetic associations linked to T2D, including 145 new loci not previously reported.
  • The study categorized T2D signals into eight distinct clusters based on their connections to cardiometabolic traits and showed that these genetic profiles are linked to vascular complications, emphasizing the role of obesity-related processes across different ancestry groups.
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  • Researchers created a new CRISPR prime editing method to generate isogenic-induced pluripotent stem cells (iPSCs) with specific genetic changes related to type 2 diabetes.
  • They developed a two-step approach to identify the best edited cell pools, which improved the efficiency of isolating individual edited cells.
  • The study showed that optimizing design elements and guide RNAs for prime editing led to a success rate of 36-73%, allowing for effective genetic modifications in iPSCs to better study diabetes-related genetic variations.
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Genome-wide association studies (GWASs) have identified hundreds of risk loci for liver disease and lipid-related metabolic traits, although identifying their target genes and molecular mechanisms remains challenging. We predicted target genes at GWAS signals by integrating them with molecular quantitative trait loci for liver gene expression (eQTL) and liver chromatin accessibility QTL (caQTL). We predicted specific regulatory caQTL variants at four GWAS signals located near EFHD1, LITAF, ZNF329, and GPR180.

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Background: Age and obesity are dominant risk factors for several common cardiometabolic disorders, and both are known to impair adipose tissue function. However, the underlying cellular and genetic factors linking aging and obesity on adipose tissue function have remained elusive. Adipose stem and precursor cells (ASPCs) are an understudied, yet crucial adipose cell type due to their deterministic adipocyte differentiation potential, which impacts the capacity to store fat in a metabolically healthy manner.

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  • - This study explores how growth patterns during puberty relate to future health outcomes by analyzing height data from about 56,000 individuals across various ancestries using a technique called SITAR.
  • - The researchers identified 26 significant genetic loci linked to height growth during puberty and found that different growth rates are associated with various health risks, like type 2 diabetes and heart conditions.
  • - The findings suggest that there are multiple growth trajectories during puberty, each influencing adult health differently, indicating that no single growth pattern is the "best" for lifelong health outcomes.
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  • This study focuses on skeletal muscle, which plays a significant role in metabolic conditions like type 2 diabetes, and aims to better understand the genetic factors behind these traits by utilizing advanced genetic mapping techniques.
  • Researchers analyzed 287 human skeletal muscle biopsies to identify various cell types and regulatory elements through single nucleus sequencing, pinpointing thousands of genetic variants, including expression and chromatin accessibility QTLs.
  • The findings revealed the importance of chromatin profiling in discovering regulatory mechanisms, indicating that specific genetic signals associated with type 2 diabetes are linked to chromatin accessibility in muscle fibers, enhancing our understanding of muscle biology and its relation to metabolic diseases.
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Complete characterization of the genetic effects on gene expression is needed to elucidate tissue biology and the etiology of complex traits. Here, we analyzed 2,344 subcutaneous adipose tissue samples and identified 34K conditionally distinct expression quantitative trait locus (eQTL) signals in 18K genes. Over half of eQTL genes exhibited at least two eQTL signals.

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Conventional measurements of fasting and postprandial blood glucose levels investigated in genome-wide association studies (GWAS) cannot capture the effects of DNA variability on 'around the clock' glucoregulatory processes. Here we show that GWAS meta-analysis of glucose measurements under nonstandardized conditions (random glucose (RG)) in 476,326 individuals of diverse ancestries and without diabetes enables locus discovery and innovative pathophysiological observations. We discovered 120 RG loci represented by 150 distinct signals, including 13 with sex-dimorphic effects, two cross-ancestry and seven rare frequency signals.

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  • Understanding how different gene expressions in fat tissue relate to cardiometabolic diseases can help identify potential health risks.
  • Researchers analyzed 859 adipose tissue samples, revealing that specific cell types, like macrophages and adipocytes, influence traits like body mass index (BMI).
  • The study found that including both BMI and cell type in analysis models led to the identification of 2,664 significant gene-trait associations, highlighting the need to consider cell diversity in genetic assessments related to metabolism.
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  • This study examines the relationship between resting heart rate and cardiovascular diseases, identifying 493 genetic variants linked to this trait through a large-scale analysis of 835,465 individuals.
  • It highlights the significance of higher genetically predicted resting heart rates, which are associated with an increased risk of dilated cardiomyopathy but lower risk for conditions like atrial fibrillation and ischemic strokes.
  • The study also challenges previous findings on resting heart rate and all-cause mortality, suggesting earlier results may have been influenced by biases, ultimately enhancing our understanding of the biological implications of resting heart rate in cardiovascular health.
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Importance: Hidradenitis suppurativa (HS) is a common and severely morbid chronic inflammatory skin disease that is reported to be highly heritable. However, the genetic understanding of HS is insufficient, and limited genome-wide association studies (GWASs) have been performed for HS, which have not identified significant risk loci.

Objective: To identify genetic variants associated with HS and to shed light on the underlying genes and genetic mechanisms.

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  • Researchers examined genetic factors influencing insulin levels after a glucose challenge in over 55,000 people from different ancestry groups, identifying ten new genetic locations linked to postprandial insulin resistance.
  • * They found that many of these loci share genetics with type 2 diabetes, suggesting a common underlying mechanism.
  • * The study also highlighted nine candidate genes affecting GLUT4, a key glucose transporter, which plays an important role in glucose uptake during the post-meal state.
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Type 2 diabetes (T2D) is a heterogeneous disease that develops through diverse pathophysiological processes. To characterise the genetic contribution to these processes across ancestry groups, we aggregate genome-wide association study (GWAS) data from 2,535,601 individuals (39.7% non-European ancestry), including 428,452 T2D cases.

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Gene regulatory effects in bulk-post mortem brain tissues are undetected at many non-coding brain trait-associated loci. We hypothesized that context-specific genetic variant function during stimulation of a developmental signaling pathway would explain additional regulatory mechanisms. We measured chromatin accessibility and gene expression following activation of the canonical Wnt pathway in primary human neural progenitors from 82 donors.

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