Genetic Pathways Leading to Fatty Liver and Atherogenic Dyslipidemia (VARKIN)

Genetic Regulation of Lipid Pathways Contributing to Non-alcoholic Fatty Liver and Atherogenic Dyslipidemia

The aims of the study are:

1. To investigate if carriers of apolipoprotein (apo) CIII loss-of-function (LOF) mutations produce less apo-CIII that results in reduction of large very low-density lipoprotein (VLDL) particle secretion as compared to non-carriers of these variants and compare the results with carriers of apo-CIII gain-of-function (GOF) to elucidate the role of apo-CIII in hepatic lipid metabolism.
2. To study if carriers of the TM6SF2 E167K and PNLPLA3 I148M mutations produce less large VLDL particles to transport fat out of the liver as compared to non-carriers.
3. To test whether the specific mutations in the apo-CIII, TM6SF2 and PNLPLA3 genes are reflected in changes of liver de novo lipogenesis (DNL), liver fat, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), plasma lipid and apolipoprotein kinetics and fasting concentrations in carriers of the TM6SF2 E167K and PNLPLA3 I148M mutations as compared to non-carriers.
4. To study the effects of APOE, angiopoietin (ANGPTL3 and ANGPTL8) or endothelial lipase (LIPG) genotypes on liver fat metabolism, lipid and apolipoprotein metabolism and lipid phenotypes.

Study Overview

• Status: Enrolling by invitation
• Conditions: Insulin Resistance; Non-alcoholic Fatty Liver; Atherogenic Dyslipidemia
• Intervention / Treatment: Diagnostic test: Lipoprotein kinetics

• Study Type: Observational
• Enrollment (Estimated): 100

Contacts and Locations

Study Locations

• Finland
  • Helsinki, Finland
    • RPU Clinical and Molecular Metabolism, Biomedicum
• Sweden
  • Gothenburg, Sweden
    • Wallenberg Laboratory

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 70 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

Ambulatory outpatients who are recruited from our previous study investigating familial dyslipidemia where exome sequency has been performed to explore genes involved in lipid metabolism (HUCH Ethics Committee, Department of Medicine: 108/1996, follow-up studies Dnro 170/E5/02, Drno 215/13/03/01/2009, Drno 144/13/03/01/2011 and HUCH Coordinating Ethics Committee Drno 184/13/03/00/2012, and Drno 183/13/03/00/2012). All subjects who have given oral consent that they can be informed about new studies focused on lipid metabolism will be contacted. To recruite the subjects we will use the invitation letter and follow up all the policy as stipulated in the Finnish biobank law (688/2012) (http//nationalbiobanks.fi/index.php./studies2/7-finrisk).

Description

Inclusion Criteria:

• persons who have provided written consent
• apo-CIII loss-of-function mutation (heterozygous) or apo-CIII gain-of-function mutations (heterozygous) or TM6SF2 E167K mutation (homozygous) or PNLPLA3 I148M or apoE or LIPG or ANGPTL3 or ANGPTL8 LOF and GOF variants. Control group without any of known risk variants in these genes.
• Hemoglobin A1c < 6.5%
• Body mass index between 18.5 and 40 kg/m²
• Estimated glomerular filtration rate > 60 ml/min/1.73 m² at inclusion

Exclusion Criteria:

• Patients with Type 1 and 2 diabetes, BMI > 40 kg/m2,
• ApoE2/2 phenotype, thyrotropin concentration outside normal range,
• Lipid-lowering drugs
• Blood pressure >160 mmHg systolic and/or > 105 diastolic mmHg
• Liver failure or abnormal liver function tests >3 x upper limit of normal
• Intestinal disease
• Pregnancy, breastfeeding
• Patients with volume depletion

Study Plan

How is the study designed?

Number of groups / cohorts

8

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
ApoC-III LOF; Carriers of apo-CIII loss-of-function mutation	Diagnostic test: Lipoprotein kinetics; Lipoprotein kinetic apply protocol that endogenously label proteins and fatty acids with stable isotope-labeled amino acid and glycerol tracers. De novo lipogenesis is measured after ingestion of deuterated water to measure newly formed fatty acids in VLDL. Liver fat is measured with magnetic resonance spectroscopy and lipolytic enzymes with heparin test.; Other Names: Measurement of de novo lipogenesis; Measurement of lipolytic activity; Measurement of liver fat
ApoC-III GOF; Carriers of apo-CIII gain-of-function mutation	Diagnostic test: Lipoprotein kinetics; Lipoprotein kinetic apply protocol that endogenously label proteins and fatty acids with stable isotope-labeled amino acid and glycerol tracers. De novo lipogenesis is measured after ingestion of deuterated water to measure newly formed fatty acids in VLDL. Liver fat is measured with magnetic resonance spectroscopy and lipolytic enzymes with heparin test.; Other Names: Measurement of de novo lipogenesis; Measurement of lipolytic activity; Measurement of liver fat
TM6SF2-KK; Carriers of TM6SF2 E167K mutation	Diagnostic test: Lipoprotein kinetics; Lipoprotein kinetic apply protocol that endogenously label proteins and fatty acids with stable isotope-labeled amino acid and glycerol tracers. De novo lipogenesis is measured after ingestion of deuterated water to measure newly formed fatty acids in VLDL. Liver fat is measured with magnetic resonance spectroscopy and lipolytic enzymes with heparin test.; Other Names: Measurement of de novo lipogenesis; Measurement of lipolytic activity; Measurement of liver fat
PNLPLA3-MM; Carriers of PNLPLA3 I148M mutation	Diagnostic test: Lipoprotein kinetics; Lipoprotein kinetic apply protocol that endogenously label proteins and fatty acids with stable isotope-labeled amino acid and glycerol tracers. De novo lipogenesis is measured after ingestion of deuterated water to measure newly formed fatty acids in VLDL. Liver fat is measured with magnetic resonance spectroscopy and lipolytic enzymes with heparin test.; Other Names: Measurement of de novo lipogenesis; Measurement of lipolytic activity; Measurement of liver fat
Control; No ApoC-III, TM6SF2 E167K or PNLPLA3 I148M mutation	Diagnostic test: Lipoprotein kinetics; Lipoprotein kinetic apply protocol that endogenously label proteins and fatty acids with stable isotope-labeled amino acid and glycerol tracers. De novo lipogenesis is measured after ingestion of deuterated water to measure newly formed fatty acids in VLDL. Liver fat is measured with magnetic resonance spectroscopy and lipolytic enzymes with heparin test.; Other Names: Measurement of de novo lipogenesis; Measurement of lipolytic activity; Measurement of liver fat
ApoE variants; Carriers of E2/2, E3/3 or E4/4 mutation	Diagnostic test: Lipoprotein kinetics; Lipoprotein kinetic apply protocol that endogenously label proteins and fatty acids with stable isotope-labeled amino acid and glycerol tracers. De novo lipogenesis is measured after ingestion of deuterated water to measure newly formed fatty acids in VLDL. Liver fat is measured with magnetic resonance spectroscopy and lipolytic enzymes with heparin test.; Other Names: Measurement of de novo lipogenesis; Measurement of lipolytic activity; Measurement of liver fat
LIPG; LIPG gene LOF or GOF variant carriers	Diagnostic test: Lipoprotein kinetics; Lipoprotein kinetic apply protocol that endogenously label proteins and fatty acids with stable isotope-labeled amino acid and glycerol tracers. De novo lipogenesis is measured after ingestion of deuterated water to measure newly formed fatty acids in VLDL. Liver fat is measured with magnetic resonance spectroscopy and lipolytic enzymes with heparin test.; Other Names: Measurement of de novo lipogenesis; Measurement of lipolytic activity; Measurement of liver fat
ANGPTL3 or ANGPTL8; ANGPTL3 and ANGPTL8 gene LOF or GOF variant carriers

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in the rate of production of VLDL Apo B	Production rate, mg/day	Baseline
Difference in the rate of production of VLDL Triglycerides	Production rate, mg/kg/day	Baseline
Difference in the rate of production of VLDL ApoC-III and apoE	Production rate, mg/kg/day	Baseline
Difference in the Fractional Catabolic Rate of VLDL Apo B	Rate of disappearance, pools/day	Baseline
Difference in the Fractional Catabolic Rate of VLDL Triglycerides	Rate of disappearance, pools/day	Baseline
Difference in the Fractional Catabolic Rate of VLDL ApoC-III and apoE	Rate of disappearance, pools/day	Baseline
Difference in de novo lipogenesis	Measure of newly synthesized triglycerides in VLDL, μmol/l	Baseline
Difference in liver fat	Percentage of liver fat measured with magnetic resonance spectroscopy	Baseline
Difference in atherogenic dyslipidemia	Remnant lipoproteins and lipoprotein fraction composition, mg/L	Baseline
Difference in insulin resistance	Calculated Homeostatic Model Assessment for Insulin Resistance (HOMA-IR)	Baseline
Difference in apoprotein A concentration	ApoA, mg/dl	Baseline
Difference in apoprotein B concentration	ApoB, mg/dl	Baseline
Difference in apoprotein C concentration	ApoC, mg/dl	Baseline
Difference in apoprotein E concentration	ApoE, mg/dl	Baseline
Difference in the rate of production and Fractional Catabolic Rate of intermediate-density Apo B	Rate of turnover, pools/day	Baseline
Difference in the rate of production and Fractional Catabolic Rate of low-density lipoprotein Apo B	Rate of turnover, pools/day	Baseline
Lipolytic activity	Measured lipoprotein lipase activity, mU/ml	Baseline
Hepatic lipase activity	Measured hepatic lipase activity, mU/ml	Baseline

Collaborators and Investigators

• Sponsor: Marja-Riitta Taskinen
• Collaborators: Göteborg University

Publications and helpful links

General Publications

• Taskinen MR, Bjornson E, Matikainen N, Soderlund S, Ramo J, Ainola MM, Hakkarainen A, Sihlbom C, Thorsell A, Andersson L, Bergh PO, Henricsson M, Romeo S, Adiels M, Ripatti S, Laakso M, Packard CJ, Boren J. Postprandial metabolism of apolipoproteins B48, B100, C-III, and E in humans with APOC3 loss-of-function mutations. JCI Insight. 2022 Oct 10;7(19):e160607. doi: 10.1172/jci.insight.160607.

Study record dates

Study Major Dates

• Study Start (Actual): December 1, 2019
• Primary Completion (Estimated): June 1, 2024
• Study Completion (Estimated): December 1, 2028

Study Registration Dates

• First Submitted: December 19, 2019
• First Submitted That Met QC Criteria: December 20, 2019
• First Posted (Actual): December 24, 2019

Study Record Updates

• Last Update Posted (Actual): September 22, 2023
• Last Update Submitted That Met QC Criteria: September 21, 2023
• Last Verified: September 1, 2023

More Information

Terms related to this study

• Keywords: Non-alcoholic Fatty Liver; Genetic variants; Apoproteins
• Additional Relevant MeSH Terms: Digestive System Diseases; Glucose Metabolism Disorders; Metabolic Diseases; Liver Diseases; Hyperinsulinism; Lipid Metabolism Disorders; Fatty Liver; Dyslipidemias; Insulin Resistance; Non-alcoholic Fatty Liver Disease
• Other Study ID Numbers: HUS/53/2017

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No