Effects of PNPLA3 I148M on hepatic lipid and very-low-density lipoprotein metabolism in humans

Background The phospholipase domain-containing 3 gene (PNPLA3)-148M variant is associated with liver steatosis but its influence on the metabolism of triglyceride-rich lipoproteins remains unclear. Here, we investigated the kinetics of large, triglyceride-rich very-low-density lipoprotein (VLDL), (VLDL1), and smaller VLDL2 in homozygotes for the PNPLA3-148M variant. Methods and results The kinetics of apolipoprotein (apo) B100 (apoB100) and triglyceride in VLDL subfractions were analysed in nine subjects homozygous for PNPLA3-148M and nine subjects homozygous for PNPLA3-148I (controls). Liver fat was >3-fold higher in the 148M subjects. Production rates for apoB100 and triglyceride in VLDL1 did not differ significantly between the two groups. Likewise, production rates for VLDL2-apoB100 and -triglyceride, and fractional clearance rates for both apoB100 and triglyceride in VLDL1 and VLDL2, were not significantly different. Conclusions Despite the higher liver fat content in PNPLA3 148M homozygotes, there was no increase in VLDL production. Equally, VLDL production was maintained at normal levels despite the putative impairment in cytosolic lipid hydrolysis in these subjects.Peer reviewe

Leveraging global multi-ancestry meta-analysis in the study of idiopathic pulmonary fibrosis genetics

The research of rare and devastating orphan diseases, such as idiopathic pulmonary fibrosis (IPF) has been limited by the rarity of the disease itself. The prognosis is poor—the prevalence of IPF is only approximately four times the incidence, limiting the recruitment of patients to trials and studies of the underlying biology. Global biobanking efforts can dramatically alter the future of IPF research. We describe a large-scale meta-analysis of IPF, with 8,492 patients and 1,355,819 population controls from 13 biobanks around the globe. Finally, we combine this meta-analysis with the largest available meta-analysis of IPF, reaching 11,160 patients and 1,364,410 population controls. We identify seven novel genome-wide significant loci, only one of which would have been identified if the analysis had been limited to European ancestry individuals. We observe notable pleiotropy across IPF susceptibility and severe COVID-19 infection and note an unexplained sex-heterogeneity effect at the strongest IPF locus MUC5B.publishedVersionPeer reviewe

KIF15 missense variant is associated with the early onset of idiopathic pulmonary fibrosis

Abstract Background: Idiopathic pulmonary fibrosis (IPF) has an unknown aetiology and limited treatment options. A recent meta-analysis identified three novel causal variants in the TERT, SPDL1, and KIF15 genes. This observational study aimed to investigate whether the aforementioned variants cause clinical phenotypes in a well-characterised IPF cohort. Methods: The study consisted of 138 patients with IPF who were diagnosed and treated at the Helsinki University Hospital and genotyped in the FinnGen FinnIPF study. Data on > 25 clinical parameters were collected by two pulmonologists who were blinded to the genetic data for patients with TERT loss of function and missense variants, SPDL1 and KIF15 missense variants, and a MUC5B variant commonly present in patients with IPF, or no variants were separately analysed. Results: The KIF15 missense variant is associated with the early onset of the disease, leading to progression to early-age transplantation or death. In patients with the KIF15 variant, the median age at diagnosis was 54.0 years (36.5–69.5 years) compared with 72.0 years (65.8–75.3 years) in the other patients (P = 0.023). The proportion of KIF15 variant carriers was 9- or 3.6-fold higher in patients aged < 55 or 65 years, respectively. The variants for TERT and MUC5B had similar effects on the patient’s clinical course, as previously described. No distinct phenotypes were observed in patients with the SPDL1 variant. Conclusions: Our study indicated the potential of KIF15 to be used in the genetic diagnostics of IPF. Further studies are needed to elucidate the biological mechanisms of KIF15 in IPF

Leveraging global multi-ancestry meta-analysis in the study of idiopathic pulmonary fibrosis genetics

Summary The research of rare and devastating orphan diseases, such as idiopathic pulmonary fibrosis (IPF) has been limited by the rarity of the disease itself. The prognosis is poor—the prevalence of IPF is only approximately four times the incidence, limiting the recruitment of patients to trials and studies of the underlying biology. Global biobanking efforts can dramatically alter the future of IPF research. We describe a large-scale meta-analysis of IPF, with 8,492 patients and 1,355,819 population controls from 13 biobanks around the globe. Finally, we combine this meta-analysis with the largest available meta-analysis of IPF, reaching 11,160 patients and 1,364,410 population controls. We identify seven novel genome-wide significant loci, only one of which would have been identified if the analysis had been limited to European ancestry individuals. We observe notable pleiotropy across IPF susceptibility and severe COVID-19 infection and note an unexplained sex-heterogeneity effect at the strongest IPF locus MUC5B