Publications by authors named "Elizabeth A Streeten"

Article Synopsis
  • Antiplatelet therapy, particularly with P2Y receptor inhibitors alongside aspirin, is essential for treating coronary artery disease, and different medication options can help tailor patient care.
  • A study investigated the effects of a specific genetic mutation (G143E in CES1) on the effectiveness of clopidogrel and ticagrelor in inhibiting platelet aggregation in patients.
  • Results showed that the G143E mutation significantly affected platelet response to clopidogrel, but not to ticagrelor, indicating ticagrelor may provide more consistent treatment for patients with clopidogrel response-altering genetics.
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Although clinical guidelines recommend measuring total plasma 25-hydroxyvitamin D (25[OH]D) to assess vitamin D (VitD) status, this index does not account for 3-fold inter-individual variation in VitD binding protein (VDBP) level. We present 3 individuals with total plasma 25(OH)D levels of 10.8 to 12.

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  • DPP4 inhibitors like sitagliptin are commonly used to treat type 2 diabetes, and this study aimed to explore genetic factors that influence individual responses to the drug.
  • In a pilot study with 47 healthy volunteers, sitagliptin was shown to significantly lower glucose levels during an oral glucose tolerance test (OGTT) and increase early insulin secretion.
  • The study noted sex differences in glucose and insulin levels over time, with females showing higher levels, but no significant sex-related differences in the drug's effect on insulin secretion were found, highlighting the T30:T60 ratio as a key metric for evaluating DPP4 inhibitor responses.
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  • The body has mechanisms to maintain calcium and vitamin D levels, with PTH playing a crucial role.
  • A study was conducted with 11 individuals who had vitamin D deficiency to investigate how these mechanisms work and to evaluate vitamin D status after supplementation.
  • Results showed significant increases in vitamin D levels after supplementation, and a specific ratio (1,25(OH)2D/24,25(OH)2D) was found to effectively predict vitamin D metabolism, highlighting the suppression of 24-hydroxylase enzyme activity as a key protective mechanism against vitamin D deficiency.
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Article Synopsis
  • This study investigates how genetic factors influence the responses to DPP4 inhibitors, like sitagliptin, used to treat type 2 diabetes.
  • A pilot study with 47 healthy volunteers showed that sitagliptin significantly reduced glucose levels and increased insulin secretion during an oral glucose tolerance test (OGTT).
  • The findings also highlighted sex differences in glucose and insulin levels but indicated that these differences did not affect the overall response to sitagliptin.
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  • Canagliflozin, a diabetes medication, may increase bone fracture risk by lowering vitamin D levels and raising parathyroid hormone (PTH), prompting concerns about its safety.
  • The study explored whether vitamin D deficiency increased vulnerability to these effects and if vitamin D3 supplementation could provide protection, involving 11 individuals from the Amish community.
  • Results showed that vitamin D3 supplementation significantly raised vitamin D levels and mitigated the adverse changes in bone-related biomarkers caused by canagliflozin, suggesting that vitamin D3 could be protective in deficient individuals.
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Aim: To validate pharmacodynamic responses to sodium-glucose co-transporter-2 (SGLT2) inhibitors and test for association with genetic variants in SLC5A4, SLC5A9, and SLC2A9.

Methods: Canagliflozin (300 mg), a SGLT2 inhibitor, was administered to 30 healthy volunteers. Several endpoints were measured to assess clinically relevant responses, including drug-induced increases in urinary excretion of glucose, sodium and uric acid.

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Context: The body has evolved homeostatic mechanisms to maintain free levels of Ca and 1,25-dihydroxyvitamin D [1,25(OH)D] within narrow physiological ranges. Clinical guidelines emphasize important contributions of PTH in maintaining this homeostasis.

Objective: To investigate mechanisms of homeostatic regulation of vitamin D (VitD) metabolism and to apply mechanistic insights to improve clinical assessment of VitD status.

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Article Synopsis
  • Glucagon-like peptide-1 receptor agonists, like exenatide, offer benefits for type 2 diabetes patients including better blood sugar control, weight loss, and lower cardiovascular risks, leading to a study aimed at finding genetic factors influencing drug effectiveness.
  • A pilot study involving 62 healthy volunteers tested exenatide versus saline, revealing that exenatide significantly boosted insulin secretion and glucose clearance but had a minimal effect on insulin sensitivity.
  • The findings highlight the importance of specific glucose metabolism measurements and support further research to explore genetic influences on the effectiveness of diabetes medications like semaglutide.
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Article Synopsis
  • Canagliflozin may increase the risk of bone fractures by lowering levels of 1,25-dihydroxyvitamin D and raising parathyroid hormone (PTH), particularly in individuals with vitamin D deficiency.
  • A study tested the effects of vitamin D3 supplementation on bone health in 11 vitamin D deficient participants from the Amish community by administering canagliflozin before and after supplementation.
  • Results showed that vitamin D3 significantly raised 25(OH)D and 24,25(OH)D levels, while reducing the adverse effects of canagliflozin on 1,25(OH)D and PTH, indicating that vitamin D3 can protect against these effects.
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Article Synopsis
  • GLP1R agonists, like exenatide, help manage type 2 diabetes by improving blood sugar control, promoting weight loss, and reducing cardiovascular risks, but individual responses to these drugs differ widely.
  • Exenatide significantly enhanced insulin secretion and glucose disappearance in a study involving 62 healthy volunteers, indicating its potential impact on glucose metabolism.
  • The findings validate the use of the FSIGT method for ongoing research into how genetic factors may influence responses to GLP1R agonists, highlighting key measures like insulin secretion and glucose effectiveness.
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Aim: SGLT2 inhibitors provide multiple benefits to patients with type 2 diabetes - including improved glycemic control and decreased risks of cardiorenal disease. Because drug responses vary among individuals, we initiated investigations to identify genetic variants associated with the magnitude of drug responses.

Methods: Canagliflozin (300 mg) was administered to 30 healthy volunteers.

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Objective: To implement, disseminate, and evaluate a sustainable method for identifying, diagnosing, and promoting individualized therapy for monogenic diabetes.

Research Design And Methods: Patients were recruited into the implementation study through a screening questionnaire completed in the waiting room or through the patient portal, physician recognition, or self-referral. Patients suspected of having monogenic diabetes based on the processing of their questionnaire and other data through an algorithm underwent next-generation sequencing for 40 genes implicated in monogenic diabetes and related conditions.

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Genetically isolated populations that arise due to recent bottleneck events have reduced genetic variation reflecting the common set of founders. Increased genetic relatedness among members of isolated populations puts them at increased risk for some recessive disorders that are rare in outbred populations. To assess the burden on reproductive health, we compared frequencies of adverse reproductive outcomes between Amish couples who were both heterozygous carriers of a highly penetrant pathogenic or likely pathogenic variant and noncarrier couples from the same Amish community.

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Article Synopsis
  • Increased levels of low-density lipoprotein cholesterol (LDL-C) and fibrinogen are major risks for cardiovascular disease, and a specific genetic variant (p.Asn352Ser) in an Amish population is linked to lower levels of both.
  • This genetic variant leads to a significant reduction in LDL-C (by 13.9 mg/dL) and fibrinogen (by 29 mg/dL), correlating with a lower risk of coronary artery disease as shown in a large analysis involving nearly 545,000 subjects.
  • The study indicates that modifying protein galactosylation might be a promising strategy for preventing cardiovascular issues, as evidenced by reduced LDL-C and fibrinogen levels noted in experiments with genetically altered mice.
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Founder populations may be enriched with certain genetic variants of high clinical impact compared to nonfounder populations due to bottleneck events and genetic drift. Using exome sequencing (ES), we quantified the load of pathogenic variants that may be clinically actionable in 6136 apparently healthy adults living in the Lancaster, PA Old Order Amish settlement. We focused on variants in 78 genes deemed clinically actionable by the American College of Medical Genetics and Genomics (ACMG) or Geisinger's MyCode Health Initiative.

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Background: In population-based research exome sequencing, the path from variant discovery to return of results is not well established. Variants discovered by research exome sequencing have the potential to improve population health.

Methods: Population-based exome sequencing and agnostic ExWAS were performed 5521 Amish individuals.

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Background: The burden of diabetes and cardiovascular risk is not uniform across the USA, with much of this disparity tracking differences in socioeconomic status, cultural practices and lifestyle. To further evaluate disparities in these disorders, we assessed the prevalence of diabetes, hypertension, and hypercholesterolemia in an Old Order Amish community that is characterized by distinctive sociocultural practices that include a very cohesive social structure and limited use of modern technologies and medications. We compared prevalence of these conditions with that of the overall US population.

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Background: Lean body mass (LM) plays an important role in mobility and metabolic function. We previously identified five loci associated with LM adjusted for fat mass in kilograms. Such an adjustment may reduce the power to identify genetic signals having an association with both lean mass and fat mass.

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Vitamin D is a steroid hormone precursor that is associated with a range of human traits and diseases. Previous GWAS of serum 25-hydroxyvitamin D concentrations have identified four genome-wide significant loci (GC, NADSYN1/DHCR7, CYP2R1, CYP24A1). In this study, we expand the previous SUNLIGHT Consortium GWAS discovery sample size from 16,125 to 79,366 (all European descent).

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Lean body mass, consisting mostly of skeletal muscle, is important for healthy aging. We performed a genome-wide association study for whole body (20 cohorts of European ancestry with n = 38,292) and appendicular (arms and legs) lean body mass (n = 28,330) measured using dual energy X-ray absorptiometry or bioelectrical impedance analysis, adjusted for sex, age, height, and fat mass. Twenty-one single-nucleotide polymorphisms were significantly associated with lean body mass either genome wide (p < 5 × 10) or suggestively genome wide (p < 2.

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