Updates on Rare Genetic Variants, Genetic Testing, and Gene Therapy in Individuals With Obesity.

PURPOSE OF REVIEW: The goal of this paper is to aggregate information on monogenic contributions to obesity in the past five years and to provide guidance for genetic testing in clinical care. RECENT FINDINGS: Advances in sequencing technologies, increasing awareness, access to testing, and new treatments have increased the utilization of genetics in clinical care. There is increasing recognition of the prevalence of rare genetic obesity from variants with mean allele frequency < 5% -new variants in known genes as well as identification of novel genes- causing monogenic obesity. While most of these genes are in the leptin melanocortin pathway, those in adipocytes may also contribute. Common variants may contribute either to higher lifetime tendency for weight gain or provide protection from monogenic obesity. While specific genetic mutations are rare, these segregate in individuals with early-onset severe obesity; thus, collectively genetic etiologies are not as rare. Some genetic conditions are amenable to targeted treatment. Research into the discovery of novel genetic causes as well as targeted treatment is growing over time. The utility of therapeutic strategies based on the genetic risk of obesity is an advancing frontier.

Automated Identification of Germline de novo Mutations in Family Trios: A Consensus-Based Informatic Approach.

Accurate identification of germline de novo variants (DNVs) remains a challenging problem despite rapid advances in sequencing technologies as well as methods for the analysis of the data they generate, with putative solutions often involving ad hoc filters and visual inspection of identified variants. Here, we present a purely informatic method for the identification of DNVs by analyzing short-read genome sequencing data from proband-parent trios. Our method evaluates variant calls generated by three genome sequence analysis pipelines utilizing different algorithms-GATK HaplotypeCaller, DeepTrio and Velsera GRAF-exploring the assumption that a requirement of consensus can serve as an effective filter for high-quality DNVs. We assessed the efficacy of our method by testing DNVs identified using a previously established, highly accurate classification procedure that partially relied on manual inspection and used Sanger sequencing to validate a DNV subset comprising less confident calls. The results show that our method is highly precise and that applying a force-calling procedure to putative variants further removes false-positive calls, increasing precision of the workflow to 99.6%. Our method also identified novel DNVs, 87% of which were validated, indicating it offers a higher recall rate without compromising accuracy. We have implemented this method as an automated bioinformatics workflow suitable for large-scale analyses without need for manual intervention.

Transbronchial Lung Cryobiopsies, Transbronchial Forceps Lung Biopsies, and Surgical Lung Biopsies in Mechanically Ventilated Patients with Acute Hypoxemic Respiratory Failure: A Retrospective Cohort Study.

IMPORTANCE: Lung biopsies are sometimes performed in mechanically ventilated patients with acute hypoxemic respiratory failure (AHRF) of unknown etiology to guide patient management. While surgical lung biopsies (SLB) offer high diagnostic rates, they may also cause significant complications. Transbronchial forceps lung biopsies (TBLB) are less invasive but often produce non-contributive specimens. Transbronchial lung cryobiopsies (TBLC) yield specimens of potentially better quality than TBLB, but due to their novel implementation in the intensive care unit (ICU), their accuracy and safety are still unclear. OBJECTIVES: Our main objective was to evaluate the risk of adverse events in patients with AHRF following the three biopsy techniques. Our secondary objectives were to assess the diagnostic yield and associated modifications of patient management of each technique. DESIGN, SETTINGS AND PARTICIPANTS: We conducted a retrospective cohort study comparing TBLC, TBLB, and SLB in mechanically ventilated patients with AHRF. MAIN OUTCOMES AND MEASURES: The primary outcome was the proportion of patients with at least one complication, and secondary outcomes included complication rates, diagnostic yields, treatment modifications, and mortality. RESULTS: Of the 26 patients who underwent lung biopsies from 2018 to 2022, all TBLC and SLB patients and 60% of TBLB patients had at least one complication. TBLC patients had higher unadjusted numbers of total and severe complications, but also worse Sequential Organ Failure Assessment scores and P/F ratios. A total of 25 biopsies (25/26, 96%) provided histopathological diagnoses, 88% (22/25) of which contributed to patient management. ICU mortality was high for all modalities (63% for TBLC, 60% for TBLB and 50% for SLB). CONCLUSIONS AND RELEVANCE: All biopsy methods had high diagnostic yields and the great majority contributed to patient management; however, complication rates were elevated. Further research is needed to determine which patients may benefit from lung biopsies and to determine the best biopsy modality.

Effect of acute high-intensity interval exercise on a mouse model of doxorubicin-induced cardiotoxicity: a pilot study.

BACKGROUND: It is unknown whether high-intensity interval exercise (HIIE) may potentiate or attenuate the cardiotoxic effect of chemotherapy agents such as doxorubicin (DOX) when performed shortly after treatment. The study aimed to investigate the effect of acute HIIE on cardiac function and structure performed either 1, 2 or 3 days after DOX injection in an animal model. METHODS: Female C57bl/6 mice (n = 28), 70 days old, received a bolus 20 mg/kg intravenous tail vein DOX injection. Three exercise groups performed 1 HIIE session (16 sets of 1 min at 85-90% of peak running speed) at 1 (n = 7), 2 (n = 7), and 3 days (n = 8) following the DOX injection. A sedentary (SED) group of mice (n = 6) did not exercise. Animals underwent echocardiography under light anesthesia (isoflurane 0.5-1%) before and 7 days after the DOX injection. Animals were sacrificed on day 9 and hearts were collected for morphometric and histological analysis. RESULTS: Animals exercising on day 3 had the smallest pre-post reduction in left ventricular fractional shortening (LVFS) (MΔ= -1.7 ± 3.3; p = 0.406) and the SED group had the largest reduction (MΔ=-6.8 ± 7.5; p = 0.009). After reclassification of animals according to their exercise compliance (performing > 8/16 of high-intensity bouts), LVFS in compliant mice was unchanged over time (LVFS MΔ= -1.3 ± 5.6; p = 0.396) while non-compliant animals had a LVFS reduction similar to sedentary animals. There were no significant differences in myocardial histology between groups. CONCLUSIONS: In this pilot murine study, one single HIIE session did not exacerbate acute doxorubicin-induced cardiotoxicity. The timing of the HIIE session following DOX injection and the level of compliance to exercise could influence the negative impact of DOX on cardiac function.

Homozygous missense variants in YKT6 result in loss of function and are associated with developmental delay, with or without severe infantile liver disease and risk for hepatocellular carcinoma.

PURPOSE: YKT6 plays important roles in multiple intracellular vesicle trafficking events but has not been associated with Mendelian diseases. METHODS: We report 3 unrelated individuals with rare homozygous missense variants in YKT6 who exhibited neurological disease with or without a progressive infantile liver disease. We modeled the variants in Drosophila. We generated wild-type and variant genomic rescue constructs of the fly ortholog dYkt6 and compared their ability in rescuing the loss-of-function phenotypes in mutant flies. We also generated a dYkt6KozakGAL4 allele to assess the expression pattern of dYkt6. RESULTS: Two individuals are homozygous for YKT6 [NM_006555.3:c.554A>G p.(Tyr185Cys)] and exhibited normal prenatal course followed by failure to thrive, developmental delay, and progressive liver disease. Haplotype analysis identified a shared homozygous region flanking the variant, suggesting a common ancestry. The third individual is homozygous for YKT6 [NM_006555.3:c.191A>G p.(Tyr64Cys)] and exhibited neurodevelopmental disorders and optic atrophy. Fly dYkt6 is essential and is expressed in the fat body (analogous to liver) and central nervous system. Wild-type genomic rescue constructs can rescue the lethality and autophagic flux defects, whereas the variants are less efficient in rescuing the phenotypes. CONCLUSION: The YKT6 variants are partial loss-of-function alleles, and the p.(Tyr185Cys) is more severe than p.(Tyr64Cys).

IgG is an aging factor that drives adipose tissue fibrosis and metabolic decline.

Aging is underpinned by pronounced metabolic decline; however, the drivers remain obscure. Here, we report that IgG accumulates during aging, particularly in white adipose tissue (WAT), to impair adipose tissue function and metabolic health. Caloric restriction (CR) decreases IgG accumulation in WAT, whereas replenishing IgG counteracts CR's metabolic benefits. IgG activates macrophages via Ras signaling and consequently induces fibrosis in WAT through the TGF-ß/SMAD pathway. Consistently, B cell null mice are protected from aging-associated WAT fibrosis, inflammation, and insulin resistance, unless exposed to IgG. Conditional ablation of the IgG recycling receptor, neonatal Fc receptor (FcRn), in macrophages prevents IgG accumulation in aging, resulting in prolonged healthspan and lifespan. Further, targeting FcRn by antisense oligonucleotide restores WAT integrity and metabolic health in aged mice. These findings pinpoint IgG as a hidden culprit in aging and enlighten a novel strategy to rejuvenate metabolic health.

Defining Optimal Settings for Lung Cryobiopsy in End-Stage Pulmonary Disease. A Human, Ex Vivo, Diseased Lung Clinical Trial.

BACKGROUND: To evaluate optimal settings of probe size, freezing time, and distance to the pleura that influence the size and quality of biopsy specimens during transbronchial lung cryobiopsies in ESPD. METHODS: We prospectively recruited 17 patients undergoing lung transplantation. We created a nonperfused ex vivo bronchoscopy setting to perform multiple cryobiopsies with different probe sizes (1.7, 1.9, and 2.4 mm), freezing times (3, 5, 7, 10, 20, 30 seconds), and probe distance from pleura (5, 10, and 20 mm). Alveolated pulmonary parenchyma area≥50% in histology was considered a good quality biopsy, with a minimum procedural artifact. We used logistic regression to identify independent parameters as risk factors for histologic adequacy. RESULTS: A total of 545 cryobiopsies were obtained from 34 explanted lungs after pneumonectomy for lung transplantation. The mean maximum diameter of the specimen achieved with the 1.7 probe was larger (13.5 mm) than those obtained with 1.9 and 2.4 mm probes (11.3 and 10.7 mm, P= 0.07). More pleural macroscopic damage and pleural tissue in histology occurred with the 2.4 mm probe ( P <0.001). There was no difference in the quality of specimens between the different freezing times and the distance from the pleura. CONCLUSIONS: Freezing time and distance from the pleura did not affect the histologic quality for diagnosing ESPD in severely damaged lungs. Smaller cryoprobe size did not negatively affect sample adequacy.

Neurodevelopmental Programming of Adiposity: Contributions to Obesity Risk.

This review analyzes the published evidence regarding maternal factors that influence the developmental programming of long-term adiposity in humans and animals via the central nervous system (CNS). We describe the physiological outcomes of perinatal underfeeding and overfeeding and explore potential mechanisms that may mediate the impact of such exposures on the development of feeding circuits within the CNS-including the influences of metabolic hormones and epigenetic changes. The perinatal environment, reflective of maternal nutritional status, contributes to the programming of offspring adiposity. The in utero and early postnatal periods represent critically sensitive developmental windows during which the hormonal and metabolic milieu affects the maturation of the hypothalamus. Maternal hyperglycemia is associated with increased transfer of glucose to the fetus driving fetal hyperinsulinemia. Elevated fetal insulin causes increased adiposity and consequently higher fetal circulating leptin concentration. Mechanistic studies in animal models indicate important roles of leptin and insulin in central and peripheral programming of adiposity, and suggest that optimal concentrations of these hormones are critical during early life. Additionally, the environmental milieu during development may be conveyed to progeny through epigenetic marks and these can potentially be vertically transmitted to subsequent generations. Thus, nutritional and metabolic/endocrine signals during perinatal development can have lifelong (and possibly multigenerational) impacts on offspring body weight regulation.

Canadian Multicentric Pan-TRK (CANTRK) Immunohistochemistry Harmonization Study.

Tumor-agnostic testing for NTRK1-3 gene rearrangements is required to identify patients who may benefit from TRK inhibitor therapies. The overarching objective of this study was to establish a high-quality pan-TRK immunohistochemistry (IHC) screening assay among 18 large regional pathology laboratories across Canada using pan-TRK monoclonal antibody clone EPR17341 in a ring study design. TRK-fusion positive and negative tumor samples were collected from participating sites, with fusion status confirmed by panel next-generation sequencing assays. Each laboratory received: (1) unstained sections from 30 cases of TRK-fusion-positive or -negative tumors, (2) 2 types of reference standards: TRK calibrator slides and IHC critical assay performance controls (iCAPCs), (3) EPR17341 antibody, and (4) suggestions for developing IHC protocols. Participants were asked to optimize the IHC protocol for their instruments and detection systems by using iCAPCs, to stain the 30 study cases, and to report the percentage scores for membranous, cytoplasmic, and nuclear staining. TRK calibrators were used to assess the analytical sensitivity of IHC protocols developed by using the 2 reference standards. Fifteen of 18 laboratories achieved diagnostic sensitivity of 100% against next-generation sequencing. The diagnostic specificity ranged from 40% to 90%. The results did not differ significantly between positive scores based on the presence of any type of staining vs the presence of overall staining in ≥1% of cells. The median limit of detection measured by TRK calibrators was 76,000 molecules/cell (range 38,000 to >200,000 molecules/cell). Three different patterns of staining were observed in 19 TRK-positive cases, cytoplasmic-only in 7 samples, nuclear and cytoplasmic in 9 samples, and cytoplasmic and membranous in 3 samples. The Canadian multicentric pan-TRK study illustrates a successful strategy to accelerate the multicenter harmonization and implementation of pan-TRK immunohistochemical screening that achieves high diagnostic sensitivity by using laboratory-developed tests where laboratories used centrally developed reference materials. The measurement of analytical sensitivity by using TRK calibrators provided additional insights into IHC protocol performance.

Rare predicted loss of function alleles in Bassoon (BSN) are associated with obesity.

Bassoon (BSN) is a component of a hetero-dimeric presynaptic cytomatrix protein that orchestrates neurotransmitter release with Piccolo (PCLO) from glutamatergic neurons throughout the brain. Heterozygous missense variants in BSN have previously been associated with neurodegenerative disorders in humans. We performed an exome-wide association analysis of ultra-rare variants in about 140,000 unrelated individuals from the UK Biobank to search for new genes associated with obesity. We found that rare heterozygous predicted loss of function (pLoF) variants in BSN are associated with higher BMI with p-value of 3.6e-12 in the UK biobank cohort. Additionally, we identified two individuals (one of whom has a de novo variant) with a heterozygous pLoF variant in a cohort of early onset or extreme obesity and report the clinical histories of these individuals with non-syndromic obesity with no history of neurobehavioral or cognitive disability. The BMI association was replicated in the All of Us whole genome sequencing data. Heterozygous pLoF BSN variants constitute a new etiology for obesity.

Consensus statement on the processing, interpretation and reporting of temporal artery biopsy for arteritis.

Giant cell arteritis (GCA) is the most common systemic vasculitis in adults in Europe and North America, typically involving the extra-cranial branches of the carotid arteries and the thoracic aorta. Despite advances in noninvasive imaging, temporal artery biopsy (TAB) remains the gold standard for establishing a GCA diagnosis. The processing of TAB depends largely on individual institutional protocol, and the interpretation and reporting practices vary among pathologists. To address this lack of uniformity, the Society for Cardiovascular Pathology formed a committee tasked with establishing consensus guidelines for the processing, interpretation, and reporting of TAB specimens, based on the existing literature. This consensus statement includes a discussion of the differential diagnoses including other forms of arteritis and noninflammatory changes of the temporal artery.

Subsecond lung cancer detection within a heterogeneous background of normal and benign tissue using single-point Raman spectroscopy.

Significance: Lung cancer is the most frequently diagnosed cancer overall and the deadliest cancer in North America. Early diagnosis through current bronchoscopy techniques is limited by poor diagnostic yield and low specificity, especially for lesions located in peripheral pulmonary locations. Even with the emergence of robotic-assisted platforms, bronchoscopy diagnostic yields remain below 80%. Aim: The aim of this study was to determine whether in situ single-point fingerprint (800 to 1700 cm-1) Raman spectroscopy coupled with machine learning could detect lung cancer within an otherwise heterogenous background composed of normal tissue and tissue associated with benign conditions, including emphysema and bronchiolitis. Approach: A Raman spectroscopy probe was used to measure the spectral fingerprint of normal, benign, and cancer lung tissue in 10 patients. Each interrogated specimen was characterized by histology to determine cancer type, i.e., small cell carcinoma or non-small cell carcinoma (adenocarcinoma and squamous cell carcinoma). Biomolecular information was extracted from the fingerprint spectra to identify biomolecular features that can be used for cancer detection. Results: Supervised machine learning models were trained using leave-one-patient-out cross-validation, showing lung cancer could be detected with a sensitivity of 94% and a specificity of 80%. Conclusions: This proof of concept demonstrates fingerprint Raman spectroscopy is a promising tool for the detection of lung cancer during diagnostic procedures and can capture biomolecular changes associated with the presence of cancer among a complex heterogeneous background within less than 1 s.

Biallelic Loss-of-Function Variants in BICD1 Are Associated with Peripheral Neuropathy and Hearing Loss.

Hearing loss and peripheral neuropathy are two clinical entities that are genetically and phenotypically heterogeneous and sometimes co-occurring. Using exome sequencing and targeted segregation analysis, we investigated the genetic etiology of peripheral neuropathy and hearing loss in a large Ashkenazi Jewish family. Moreover, we assessed the production of the candidate protein via western blotting of lysates from fibroblasts from an affected individual and an unaffected control. Pathogenic variants in known disease genes associated with hearing loss and peripheral neuropathy were excluded. A homozygous frameshift variant in the BICD1 gene, c.1683dup (p.(Arg562Thrfs*18)), was identified in the proband and segregated with hearing loss and peripheral neuropathy in the family. The BIDC1 RNA analysis from patient fibroblasts showed a modest reduction in gene transcripts compared to the controls. In contrast, protein could not be detected in fibroblasts from a homozygous c.1683dup individual, whereas BICD1 was detected in an unaffected individual. Our findings indicate that bi-allelic loss-of-function variants in BICD1 are associated with hearing loss and peripheral neuropathy. Definitive evidence that bi-allelic loss-of-function variants in BICD1 cause peripheral neuropathy and hearing loss will require the identification of other families and individuals with similar variants with the same phenotype.

Predicted loss of function alleles in Bassoon (BSN) are associated with obesity.

Bassoon ( BSN ) is a component of a hetero-dimeric presynaptic cytomatrix protein that orchestrates neurotransmitter release with Piccolo ( PCLO ) from glutamatergic neurons throughout the brain. Heterozygous missense variants in BSN have previously been associated with neurodegenerative disorders in humans. We performed an exome-wide association analysis of ultra-rare variants in about 140,000 unrelated individuals from the UK Biobank to search for new genes associated with obesity. We found that rare heterozygous predicted loss of function (pLoF) variants in BSN are associated with higher BMI with log10-p value of 11.78 in the UK biobank cohort. The association was replicated in the All of Us whole genome sequencing data. Additionally, we have identified two individuals (one of whom has a de novo variant) with a heterozygous pLoF variant in a cohort of early onset or extreme obesity at Columbia University. Like the individuals identified in the UKBB and All of us Cohorts, these individuals have no history of neurobehavioral or cognitive disability. Heterozygosity for pLoF BSN variants constitutes a new etiology for obesity.

Transbronchial Lung Cryobiopsy and Surgical Lung Biopsy: A Prospective Multi-Centre Agreement Clinical Trial (CAN-ICE).

Rationale: Transbronchial cryobiopsy (TBCB) for the diagnosis of interstitial lung disease (ILD) has shown promising results, but prospective studies with matched surgical lung biopsy (SLB) have yielded conflicting results. Objectives: We aimed to assess within- and between-center diagnostic agreement between TBCB and SLB at both the histopathologic and multidisciplinary discussion (MDD) levels in patients with diffuse ILD. Methods: In a multicenter prospective study, we performed matched TBCB and SLB in patients referred for SLB. After a blinded review by three pulmonary pathologists, all cases were reviewed by three independent ILD teams in an MDD. MDD was performed first with TBCB, then with SLB in a second session. Within-center and between-center diagnostic agreement was evaluated using percentages and correlation coefficients. Measurements and Main Results: Twenty patients were recruited and underwent contemporaneous TBCB and SLB. Within-center diagnostic agreement between TBCB-MDD and SLB-MDD was reached in 37 of the 60 (61.7%) paired observations, resulting in a Cohen's κ value of 0.46 (95% confidence interval [CI], 0.29-0.63). Diagnostic agreement increased among high-confidence or definitive diagnoses on TBCB-MDD (21 of 29 [72.4%]), but not significantly, and was more likely among cases with SLB-MDD diagnoses of idiopathic pulmonary fibrosis than fibrotic hypersensitivity pneumonitis (13 of 16 [81.2%] vs. 16 of 31 [51.6%]; P = 0.047). Between-center agreement for cases was markedly higher for SLB-MDD (κ = 0.71 [95% CI, 0.52-0.89]) than TBCB-MDD (κ = 0.29 [95% CI, 0.09-0.49]). Conclusions: This study demonstrated moderate TBCB-MDD and SLB-MDD diagnostic agreement for ILD, while between-center agreement was fair for TBCB-MDD and substantial for SLB-MDD. Clinical trial registered with www.clinicaltrials.gov (NCT02235779).

Dataset for the reporting of neoplasms of the heart, pericardium, and great vessels: recommendations from the International Collaboration on Cancer Reporting (ICCR).

The International Collaboration on Cancer Reporting (ICCR) was founded by major pathology organizations from around the world to produce internationally standardized and evidence-based datasets for pathologists' reporting of cancer. Its goal is to improve cancer patient outcomes worldwide and to advance international benchmarking in cancer management. The ICCR cancer dataset development schedule is aligned with revisions of the WHO Classification of Tumours ("Blue Book") series, and in 2015 ICCR developed an initial series of thoracic datasets including a dataset for neoplasms of the heart, pericardium, and great vessels. This edition has now been updated to align with the 2021 WHO Blue Book series. An expert panel was convened to review and revise the dataset. While the majority of ICCR datasets are focused on malignant tumors, the scope of this dataset includes a number of benign tumors and tumor-like entities because of the rarity of cardiac malignancies and the serious implications of even histologically benign lesions. Due to the rarity of cardiac tumors, evidence in support of reporting elements is limited.

Sudden cardiac death in the young: A consensus statement on recommended practices for cardiac examination by pathologists from the Society for Cardiovascular Pathology.

Sudden cardiac death is, by definition, an unexpected, untimely death caused by a cardiac condition in a person with known or unknown heart disease. This major international public health problem accounts for approximately 15-20% of all deaths. Typically more common in older adults with acquired heart disease, SCD also can occur in the young where the cause is more likely to be a genetically transmitted process. As these inherited disease processes can affect multiple family members, it is critical that these deaths are appropriately and thoroughly investigated. Across the United States, SCD cases in those less than 40 years of age will often fall under medical examiner/coroner jurisdiction resulting in scene investigation, review of available medical records and a complete autopsy including toxicological and histological studies. To date, there have not been consistent or uniform guidelines for cardiac examination in these cases. In addition, many medical examiner/coroner offices are understaffed and/or underfunded, both of which may hamper specialized examinations or studies (e.g., molecular testing). Use of such guidelines by pathologists in cases of SCD in decedents aged 1-39 years of age could result in life-saving medical intervention for other family members. These recommendations also may provide support for underfunded offices to argue for the significance of this specialized testing. As cardiac examinations in the setting of SCD in the young fall under ME/C jurisdiction, this consensus paper has been developed with members of the Society of Cardiovascular Pathology working with cardiovascular pathology-trained, practicing forensic pathologists.

Amyloid Deposits in a Functionally Unicuspid Stenotic Aortic Valve.

Amyloidosis concomitant to aortic stenosis usually occurs with myocardial infiltration by the transthyretin protein. To our knowledge, this is the first report of localized amyloidosis of indeterminate type in a severely calcified and functionally unicuspid aortic valve. Isolated dystrophic valvular amyloidosis is believed to be related to fibrocalcific valve disease. In light of the literature on this topic, the present case raises new hypotheses on pathophysiology and further supports the contributory role of unusual non-tricuspid valve morphology in the development of dystrophic amyloid, likely secondary to altered hemodynamic stress.

Une amyloïdose associée à une sténose aortique survient généralement avec infiltration du myocarde par la protéine transthyrétine. Le cas que nous décrivons est, à notre connaissance, le premier cas rapporté d'amyloïdose localisée de type indéterminé dans une valve aortique sévèrement calcifiée et fonctionnellement unicuspide. L'amyloïdose valvulaire dystrophique isolée serait liée à l'atteinte fibrocalcique de la valve. À la lumière de la littérature à ce sujet, le cas décrit ici permet de soulever de nouvelles hypothèses physiopathologiques et appuie le lien entre une morphologie valvulaire inhabituelle (non tricuspide) et l'apparition de substances amyloïdes dystrophiques, probablement secondaire à une altération des contraintes hémodynamiques.

The metabolic conditioning of obesity: A review of the pathogenesis of obesity and the epigenetic pathways that "program" obesity from conception.

Understanding the developmental origins of health and disease is integral to overcome the global tide of obesity and its metabolic consequences, including atherosclerotic cardiovascular disease, type 2 diabetes, hyperlipidemia, and nonalcoholic fatty liver disease. The rising prevalence of obesity has been attributed, in part, to environmental factors including the globalization of the western diet and unhealthy lifestyle choices. In this review we argue that how and when such exposures come into play from conception significantly impact overall risk of obesity and later health outcomes. While the laws of thermodynamics dictate that obesity is caused by an imbalance between caloric intake and energy expenditure, the drivers of each of these may be laid down before the manifestation of the phenotype. We present evidence over the last half-century that suggests that the temporospatial evolution of obesity from intrauterine life and beyond is, in part, due to the conditioning of physiological processes at critical developmental periods that results in maladaptive responses to obesogenic exposures later in life. We begin the review by introducing studies that describe an association between perinatal factors and later risk of obesity. After a brief discussion of the pathogenesis of obesity, including the systemic regulation of appetite, adiposity, and basal metabolic rate, we delve into the mechanics of how intrauterine, postnatal and early childhood metabolic environments may contribute to adult obesity risk through the process of metabolic conditioning. Finally, we detail the specific epigenetic pathways identified both in preclinical and clinical studies that synergistically "program" obesity.

Reduced calcium levels and accumulation of abnormal insulin granules in stem cell models of HNF1A deficiency.

Mutations in HNF1A cause Maturity Onset Diabetes of the Young (HNF1A-MODY). To understand mechanisms of ß-cell dysfunction, we generated stem cell-derived pancreatic endocrine cells with hypomorphic mutations in HNF1A. HNF1A-deficient ß-cells display impaired basal and glucose stimulated-insulin secretion, reduced intracellular calcium levels in association with a reduction in CACNA1A expression, and accumulation of abnormal insulin granules in association with SYT13 down-regulation. Knockout of CACNA1A and SYT13 reproduce the relevant phenotypes. In HNF1A deficient ß-cells, glibenclamide, a sulfonylurea drug used in the treatment of HNF1A-MODY patients, increases intracellular calcium, and restores insulin secretion. While insulin secretion defects are constitutive in ß-cells null for HNF1A, ß-cells heterozygous for hypomorphic HNF1A (R200Q) mutations lose the ability to secrete insulin gradually; this phenotype is prevented by correction of the mutation. Our studies illuminate the molecular basis for the efficacy of treatment of HNF1A-MODY with sulfonylureas, and suggest promise for the use of cell therapies.