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J Hepatol. 2015 Mar;62(3):657-63. doi: 10.1016/j.jhep.2014.10.010. Epub 2014 Oct 19.

Circulating triacylglycerol signatures and insulin sensitivity in NAFLD associated with the E167K variant in TM6SF2.

Author information

1
Minerva Foundation Institute for Medical Research, Helsinki, Finland.
2
Minerva Foundation Institute for Medical Research, Helsinki, Finland; CIBERDEM, Endocrinology Unit, Joan XXIII University Hospital, IISPV Pere Virgili Health Research Institute, Rovira i Virgili University, Tarragona, Spain.
3
Steno Diabetes Center, Niels Steensens Vej 2, 2820 Gentofte, Denmark.
4
Department of Clinical Sciences, Diabetes and Cardiovascular Disease Genetic Epidemiology, Skånes University Hospital, Lund University Diabetes Center, Lund University, Malmö, Sweden.
5
Minerva Foundation Institute for Medical Research, Helsinki, Finland; Department of Medicine, University of Helsinki, Helsinki, Finland. Electronic address: ykijarvi@cc.helsinki.fi.

Abstract

BACKGROUND & AIMS:

The Glu167Lys (E167K) variant in the transmembrane 6 superfamily member 2 protein (TM6SF2) was recently shown to influence liver fat (LFAT) content. We aimed at studying how this variant influences circulating triacylglycerol (TAG) signatures and whether it influences hepatic or adipose tissue insulin sensitivity.

METHODS:

We genotyped 300 Finnish subjects for the E167K (rs58542926) variant in TM6SF2 and for the I148M (rs738409) variant in the patatin-like phospholipase domain-containing protein 3 (PNPLA3) in whom LFAT was measured using 1H-MRS and circulating lipids by UPLC-MS. We compared the plasma lipidome between E167K carriers (TM6SF2EK/KK) and non-carriers (TM6SF2EE), and between three groups of NAFLD: (i) carriers of the E167K but not of the I148M variant in PNPLA3 ('TM6SF2 NAFLD'), (ii) carriers of the I148M but not of the E167K variant ('PNPLA3 NAFLD'), and (iii) non-carriers of either risk allele ('Non-risk NAFLD'). Hepatic and adipose tissue insulin sensitivities were measured using the euglycemic hyperinsulinemic clamp technique combined with infusion of [3-3H]glucose in 111 subjects.

RESULTS:

The LFAT content was 34% higher in the TM6SF2EK/KK (13.07±1.57%) than in the TM6SF2EE group (9.77±0.58%, p=0.013). The effect of insulin on glucose production and lipolysis were significantly higher in the TM6SF2EK/KK than in the TM6SF2EE group. Comparison of the three NAFLD groups with similar LFATs showed that both the 'TM6SF2 NAFLD' and 'PNPLA3 NAFLD' had significantly lower triglyceride levels and were characterized by lower levels of most common TAGs compared to the 'Non-risk NAFLD' group.

CONCLUSIONS:

We conclude that the E167K variant in TM6SF2 is associated with a distinct subtype of NAFLD, characterized by preserved insulin sensitivity with regard to lipolysis, hepatic glucose production and lack of hypertriglyceridemia despite a clearly increased LFAT content.

KEYWORDS:

Glucose production; Lipolysis; Liver; Magnetic resonance spectroscopy; Mass spectrometry

PMID:
25457209
DOI:
10.1016/j.jhep.2014.10.010
[Indexed for MEDLINE]

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