Exome sequencing reveals IFT172 variants in patients with non-syndromic cholestatic liver disease.

BACKGROUND AND AIM: Gene defects contribute to the aetiology of intrahepatic cholestasis. We aimed to explore the outcome of whole-exome sequencing (WES) in a cohort of 51 patients with this diagnosis. PATIENTS AND METHODS: Both paediatric (n = 33) and adult (n = 18) patients with cholestatic liver disease of unknown aetiology were eligible. WES was used for reassessment of 34 patients (23 children) without diagnostic genotypes in ABCB11, ATP8B1, ABCB4 or JAG1 demonstrable by previous Sanger sequencing, and for primary assessment of additional 17 patients (10 children). Nasopharyngeal swab mRNA was analysed to address variant pathogenicity in two families. RESULTS: WES revealed biallelic variation in 3 ciliopathy genes (PKHD1, TMEM67 and IFT172) in 4 clinically unrelated index subjects (3 children and 1 adult), heterozygosity for a known variant in PPOX in one adult index subject, and homozygosity for an unreported splice-site variation in F11R in one child. Whereas phenotypes of the index patients with mutated PKHD1, TMEM67, and PPOX corresponded with those elsewhere reported, how F11R variation underlies liver disease remains unclear. Two unrelated patients harboured different novel biallelic variants in IFT172, a gene implicated in short-rib thoracic dysplasia 10 and Bardet-Biedl syndrome 20. One patient, a homozygote for IFT172 rs780205001 c.167A>C p.(Lys56Thr) born to first cousins, had liver disease, interpreted on biopsy aged 4y as glycogen storage disease, followed by adult-onset nephronophthisis at 25y. The other, a compound heterozygote for novel frameshift variant IFT172 NM_015662.3 c.2070del p.(Met690Ilefs*11) and 2 syntenic missense variants IFT172 rs776310391 c.157T>A p.(Phe53Ile) and rs746462745 c.164C>G p.(Thr55Ser), had a severe 8mo cholestatic episode in early infancy, with persisting hyperbilirubinemia and fibrosis on imaging studies at 17y. No patient had skeletal malformations. CONCLUSION: Our findings suggest association of IFT172 variants with non-syndromic cholestatic liver disease.

Low Frequency of Cancer-Predisposition Gene Mutations in Liver Transplant Candidates with Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) mainly stems from liver cirrhosis and its genetic predisposition is believed to be rare. However, two recent studies describe pathogenic/likely pathogenic germline variants (PV) in cancer-predisposition genes (CPG). As the risk of de novo tumors might be increased in PV carriers, especially in immunosuppressed patients after a liver transplantation, we analyzed the prevalence of germline CPG variants in HCC patients considered for liver transplantation. Using the panel NGS targeting 226 CPGs, we analyzed germline DNA from 334 Czech HCC patients and 1662 population-matched controls. We identified 48 PVs in 35 genes in 47/334 patients (14.1%). However, only 7/334 (2.1%) patients carried a PV in an established CPG (PMS2, 4×NBN, FH or RET). Only the PV carriers in two MRN complex genes (NBN and RAD50) were significantly more frequent among patients over controls. We found no differences in clinicopathological characteristics between carriers and non-carriers. Our study indicated that the genetic component of HCC is rare. The HCC diagnosis itself does not meet criteria for routine germline CPG genetic testing. However, a low proportion of PV carriers may benefit from a tailored follow-up or targeted therapy and germline testing could be considered in liver transplant recipients.

Alpha-1 Antitrypsin and Hepatocellular Carcinoma in Liver Cirrhosis: SERPINA1 MZ or MS Genotype Carriage Decreases the Risk.

Heterozygotes for Z or S alleles of alpha-1-antrypsin (AAT) have low serum AAT levels. Our aim was to compare the risk of hepatocellular carcinoma (HCC) in patients with liver cirrhosis carrying the SERPINA1 MM, MZ and MS genotypes. The study groups consisted of 1119 patients with liver cirrhosis of various aetiologies, and 3240 healthy individuals served as population controls. The MZ genotype was significantly more frequent in the study group (55/1119 vs. 87/3240, p < 0.0001). The MS genotype frequency was comparable in controls (32/119 vs. 101/3240, p = 0.84). MZ and MS heterozygotes had lower serum AAT level than MM homozygotes (medians: 0.90 g/L; 1.40 g/L and 1.67 g/L; p < 0.001 for both). There were significantly fewer patients with HCC in the cirrhosis group among MZ and MS heterozygotes than in MM homozygotes (5/55 and 1/32 respectively, vs. 243/1022, p < 0.01 for both). The risk of HCC was lower in MZ and MS heterozygotes than in MM homozygotes (OR 0.3202; 95% CI 0.1361-0.7719 and OR 0.1522; 95% CI 0.02941-0.7882, respectively). Multivariate analysis of HCC risk factors identified MZ or MS genotype carriage as a protective factor, whereas age, male sex, BMI and viral aetiology of cirrhosis increased HCC risk.

Liver stiffness measured by two-dimensional shear-wave elastography predicts hepatic vein pressure gradient at high values in liver transplant candidates with advanced liver cirrhosis.

Liver stiffness is a reliable non-invasive predictor of Hepatic Venous Pressure Gradient (HVPG) above 10 mm Hg. However, it failed to predict higher thresholds of HVPG. Our aim was to investigate whether liver stiffness and selected previously published non-invasive blood biomarkers could predict higher HVPG thresholds in liver transplant candidates without ongoing alcohol use. One hundred and nine liver transplant candidates with liver cirrhosis of various aetiologies underwent direct HVPG measurement, liver stiffness measurement by 2D shear-wave elastography (Aixplorer Multiwave, Supersonic Imagine, France) and assessment of blood HVPG biomarkers (osteopontin, VCAM-1, IL-6, TNF-α, IL-1ra/IL-1F3 and ELF score). The correlation between liver stiffness and HVPG was linear up to 30 mm Hg of HVPG (r = 0.765, p < 0.0001). The regression lines had similar slopes for HVPG values below and above 16 mm Hg (p > 0.05) and the correlation in patients with HVPG <16 mm Hg (r = 0.456, p = 0.01) was similar to patients with HVPG ≥ 16 mm Hg (r = 0.499, p < 0.0001). The correlation was similar in the subgroup patients with alcoholic (r = 0.718, p < 0.0001), NASH (r = 0.740, p = 0.008), cryptogenic (r = 0.648, p = 0,0377), cholestatic and autoimmune (r = 0.706, p < 0.0001) and viral cirrhosis (r = 0.756, p < 0.0001). Liver stiffness distinguished patients with HVPG above 16, and 20 mm Hg with AUROCs 0.90243, and 0.86824, sensitivity 0.7656, and 0.7027, and specificity 0.9333, and 0.8750. All studied blood biomarkers correlated better with liver stiffness than with HVPG and their AUROCs did not exceed 0.8 at both HVPG thresholds. Therefore, a composite predictor superior to liver stiffness could not be established. We conclude that liver stiffness is a clinically reliable predictor of higher HVPG thresholds in non-drinking subjects with advanced liver cirrhosis.

Donor PNPLA3 and TM6SF2 Variant Alleles Confer Additive Risks for Graft Steatosis After Liver Transplantation.

BACKGROUND: The rs58542926 polymorphism in transmembrane 6 superfamily member 2 (TM6SF2) is a genetic factor predisposing to nonalcoholic fatty liver disease. We aimed to explore the effect of recipient and donor TM6SF2 rs58542926 genotypes on liver graft fat content after liver transplantation. METHODS: Steatosis was evaluated in liver biopsies from 268 adult recipients. The influence of recipient and donor TM6SF2 genotypes, patatin-like phospholipase domain-containing 3 (PNPLA3) rs738409 genotypes, and nongenetic factors on the steatosis grade assessed 6-30 months after transplantation was analyzed by ordinal logistic regression. RESULTS: The presence of the TM6SF2 c.499A allele in the donor (P = 0.014), PNPLA3 c.444G allele in the donor (P < 0.001), posttransplant body mass index (P < 0.001), and serum triglycerides (P = 0.047) independently predicted increased liver fat content on multivariable analysis, whereas noncirrhotic liver disease, as an indication for liver transplantation, was associated with lower risk of steatosis (P = 0.003). The effects of the donor TM6SF2 A and PNPLA3 G alleles were additive, with an odds ratio of 4.90 (95% confidence interval, 2.01-13.00; P < 0.001), when both minor alleles were present compared with an odds ratio of 2.22 (95% confidence interval, 1.42-3.61; P = 0.002) when only one of these alleles was present. CONCLUSIONS: The donor TM6SF2 c.499A allele is an independent risk factor of liver graft steatosis after liver transplantation that is additive to the effects of donor PNPLA3 c.444G allele.

ABCB4 disease mimicking morbus Wilson: A potential diagnostic pitfall.

INTRODUCTION: Progressive familial intrahepatic cholestasis type 3 (PFIC3) is a rare autosomal recessive cholestatic liver disorder caused by genetic deficiency of ATP-binding cassette subfamily B member 4 (ABCB4), a hepatocanalicular floppase translocating phospholipids from the inner to the outer leaflet of the canalicular membrane lipid bilayer. PFIC3 is characterised by production of hydrophilic bile with lithogenic properties which is harmful to the hepatobiliary epithelia. Chronic cholestasis in some patients may be accompanied by excessive accumulation of copper in the liver and by increased urinary copper excretion, the findings mimicking Wilson disease (WD). METHODS AND RESULTS: We report an 11 y/o male patient with growth retardation, mild craniofacial dysmorphic features and chronic liver disease, initially diagnosed and treated as WD. Whereas genetic testing for WD was negative, further molecular and histopathological analysis revealed two novel mutations (c.833+1G>T and c.1798T>A) in ABCB4 and complete absence of the ABCB4/MDR3 protein in the liver, determining PFIC3 as the correct diagnosis. CONCLUSION: PFIC3 and WD display pleomorphic and sometimes overlapping clinical and laboratory features, which may pose a differential diagnostic problem. Since the patient management in WD and PFIC3 differs significantly, an early and accurate diagnosis is crucial for optimising of therapeutic approach and prevention of possible complications.

PNPLA3 rs738409 G allele carriers with genotype 1b HCV cirrhosis have lower viral load but develop liver failure at younger age.

BACKGROUND: PNPLA3 rs738409 minor allele c.444G represents a risk factor for liver steatosis and fibrosis progression also in chronic hepatitis C (HCV). We investigated its impact on the timing of liver transplantation (LT) in patients with genotype 1b HCV cirrhosis. METHODS: We genotyped and evaluated 172 LT candidates with liver cirrhosis owing to chronic HCV infection, genotype 1b. One hundred patients needed LT for chronic liver failure (CLF) and 72 for a small hepatocellular carcinoma (HCC) in the cirrhotic liver without CLF. Population controls (n = 647) were selected from the Czech cross-sectional study MONICA. RESULTS: The CLF patients were younger (53.5 ± 7.2 vs. 59.6 ± 6.6, P < 0.001) with more advanced liver disease than HCC patients (Child-Pugh's score 9.1 ± 1.8 vs. 7.1 ± 1.9, P < 0.001, MELD 14.1 ± 3.9 vs. 11.1 ± 3.7, P < 0.001). PNPLA3 G allele increased the risk of LT for CLF in both allelic and recessive models (CG + GG vs. CC: OR, 1.90; 95% CI, 1.017-3.472, P = 0.045 and GG vs. CC + CG: OR, 2.94; 95% CI, 1.032-7.513, P = 0.042). Multivariate analysis identified younger age (P < 0.001) and the G allele (P < 0.05) as risk factors for CLF. The genotype frequencies between the CLF group and MONICA study significantly differed in both, allelic and recessive model (P = 0.004, OR 1.87, 95% CI 1.222-2.875; P < 0.001, OR 3.33, 95% CI 1.824-6.084, respectively). The OR values almost doubled in the recessive model compared with the allelic model suggesting the additive effect of allele G. In contrast, genotype frequencies in the HCC group were similar to the MONICA study in both models. Pretransplant viral load was significantly lower in GG than in CC + CG genotypes (median, IQR; 162,500 (61,550-319,000) IU/ml vs. 570,000 (172,000-1,595,000) IU/ml, P < 0.0009). CONCLUSIONS: Our results suggest that PNPLA3 rs738409 G allele carriage may be associated with a faster progression of HCV cirrhosis to chronic liver failure.

IL28B rs12979860 T allele protects against CMV disease in liver transplant recipients in the post-prophylaxis and late period.

BACKGROUND: Cytomegalovirus (CMV) disease represents a serious complication in liver transplant (OLT) recipients. CMV prophylaxis reduces incidence of CMV disease in the early post-transplant period (on-prophylaxis disease, OPD) but may postpone its manifestation after the completion of prophylaxis. Post-prophylaxis disease (PPD) incidence after prophylaxis cessation may be modified by genetic factors. METHODS: We analyzed impact of IL28B rs1297986 variants on CMV disease incidence in 743 adult OLT recipients receiving universal prophylaxis. RESULTS: One hundred and forty-four (19.4%) patients had at least one CMV disease episode. One hundred and two of them (70.8%) had at least one OPD and 36 (25%) patients had PPD, six (4.2%) patients had both. The rate of IL28B T allele carriers was lower in PPD group (38.9%) in comparison with OPD group (66.7%, P = 0.005) and group without CMV disease (61.4%, P = 0.009). The impact of IL28B genotype on the risk of CMV OPD was significant neither in the allelic (TT + CT vs CC, P = 0.32) nor in the recessive model (TT vs CT + CC, P = 0.79). Contrarily, in the PPD group, T allele (TT + CT vs CC) had a protective effect, OR 0.4 (95% CI 0.2-0.8, P = 0.008). Further risk factors of PPD were age <55 years and valganciclovir prophylaxis, whereas the risk factors of OPD were age <55 years, cyclosporine A therapy and pre-transplant CMV serostatus (donor +/recipient -). CONCLUSIONS: IL28B rs12979860 T allele carriers had a lower risk of CMV PPD.

Variable X-chromosome inactivation and enlargement of pericentral glutamine synthetase zones in the liver of heterozygous females with OTC deficiency.

Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder that causes recurrent and life-threatening episodes of hyperammonemia. The clinical picture in heterozygous females is highly diverse and derives from the genotype and the degree of inactivation of the mutated X chromosome in hepatocytes. Here, we describe molecular genetic, biochemical, and histopathological findings in the livers explanted from two female patients with late-onset OTC deficiency. Analysis of X-inactivation ratios by DNA methylation-based assays showed remarkable intra-organ variation ranging from 46:54 to 82:18 (average 70:30, n = 37), in favor of the active X chromosome carrying the mutation c.583G>C (p.G195R), in the first patient and from 75:25 to 90:10 (average 82:18, n = 20) in favor of the active X chromosome carrying the splicing mutation c.663+1G>A in the second patient. The X-inactivation ratios in liver samples correlated highly with the proportions of OTC-positive hepatocytes calculated from high-resolution image analyses of the immunohistochemically detected OTC in frozen sections that was performed on total area > 5 cm2. X-inactivation ratios in blood in both female patients corresponded to the lower limit of the liver values. Our data indicate that the proportion of about 20-30% of hepatocytes expressing the functional OTC protein is not sufficient to maintain metabolic stability. X-inactivation ratios assessed in liver biopsies taken from heterozygous females with X-linked disorders should not be considered representative of the whole liver.

Rare variants in known and novel candidate genes predisposing to statin-associated myopathy.

AIM: Genetic variants affecting statin uptake, metabolism or predisposing to muscular diseases may confer susceptibility to statin-induced myopathy. Besides the SLCO1B1 rs4149056 genotype, common genetic variants do not seem to determine statin-associated myopathy. Here we aimed to address the potential role of rare variants. METHODS: We performed whole exome sequencing in 88 individuals suffering from statin-associated myopathy and assessed the burden of rare variants using candidate-gene and exome-wide association analysis. RESULTS: In the novel candidate gene CLCN1, we identified a heterozygote truncating mutation p.R894* in four patients. In addition, we detected predictably pathogenic case-specific variants in MYOT, CYP3A5, SH3TC2, FBXO32 and RBM20. CONCLUSION: These findings support the role of rare variants and nominate loci for follow-up studies.

Relevance of low viral load in haemodialysed patients with chronic hepatitis C virus infection.

AIM: To identify predictors of sustained virological response in hemodialysed patients treated by PEGinterferon α for chronic hepatitis C, genotype 1. METHODS: The sustained virological response (SVR) rate, IL28B genotype, IFNL4 genotype, initial viral load (IVL) and other pretreatment variables in 39 end-stage renal disease patients (ESRD) on maintenance haemodialysis (HD) infected with hepatitis C virus (HCV), genotype 1b, were compared with a control group of 109 patients with normal kidney function treated within the same period. All the patients were treatment naïve and had well compensated liver disease. The ESRD patients received 135 µg of PEGylated interferon α-2a (PegIFN-α) weekly and a reduced dose of ribavirin (RBV) was administered to 23/39 patients with an initial haemoglobin level > 10 g/dL. Control group patients were given standard doses of PegIFN-α and RBV. SVR was assessed as HCV RNA negativity 24 wk post-treatment. A t-test or ANOVA were used for comparisons of the means and a χ(2) test compared the frequencies. Logistic regression was used to determine significant predictors of SVR. Cutoff values for continuous variables were obtained from Receiver Operating Characteristic analysis. RESULTS: The distribution of IL28B rs12979860 CC, CT and TT genotypes in the ESRD group was 28.2%, 64.1% and 7.7%, respectively, and 19.3%, 62.4% and 18.3% in the controls. The IFNL4 genotype was in almost absolute linkage disequlibrium with IL28B. The proportion of patients with a low IVL (< 600000 IU/mL) was significantly higher in the ESRD group than in the controls (28/39, 71.8% vs 51/109, 46.8%, P = 0.009), as was the proportion of patients with low IVL in IL28B CC carriers compared with non-CC carriers in the ESRD group (10/11, 90.9% vs 18/28, 64.3%, P = 0.0035). This difference was not found in the controls (7/22, 31.8% vs 44/87, 50.6%, P = 0.9). The overall SVR rate was 64.1% (25/39) in the ESRD group and 50.5% (55/109) in the control group (P = 0.19). 11/11 (100%) and 19/22 (86.4%) IL28B CC patients achieved SVR in the ESRD and control groups, respectively. A statistically significant association between SVR and IL28B and IFNL4 variants was found in both groups. The ESRD patients who achieved SVR showed the lowest IVL [median 21000, interquartile range (IQR): 6000-23000 IU/mL], compared with ESRD individuals without SVR (1680000, IQR: 481000-6880000, P = 0.001), controls with SVR (387000, IQR: 111000-1253000) and controls without SVR (905000, IQR: 451000-3020000). In ESRD, an IVL < 600000 IU/mL was strongly associated with SVR: 24/28 (85.7%) patients who achieved SVR had viraemia below this threshold. CONCLUSION: Haemodialysis decreases the viral load, especially in IL28B CC genotype carriers. A low IVL was the strongest predictor of SVR in ESRD patients identified in multivariate analysis.

NKD1 marks intestinal and liver tumors linked to aberrant Wnt signaling.

The activity of the Wnt pathway undergoes complex regulation to ensure proper functioning of this principal signaling mechanism during development of adult tissues. The regulation may occur at several levels and includes both positive and negative feedback loops. In the present study we employed one of such negative feedback regulators, naked cuticle homolog 1 (Nkd1), to follow the Wnt pathway activity in the intestine and liver and in neoplasia originated in these organs. Using lineage tracing in transgenic mice we localized Nkd1 mRNA to the bottom parts of the small intestinal crypts and hepatocytes surrounding the central vein of the hepatic lobule. Furthermore, in two mouse models of intestinal tumorigenesis, Nkd1 expression levels were elevated in tumors when compared to healthy tissue. We utilized a collection of human intestinal polyps and carcinomas to confirm that NKD1 represents a robust marker of neoplastic growth. In addition, expression analysis of NKD1 in liver cancer showed that high expression levels of the gene distinguish a subclass of hepatocellular carcinomas related to aberrant Wnt signaling. Finally, our results were confirmed by bioinformatic analysis of large publicly available datasets that included gene expression profiling and high-throughput sequencing data of human colon and liver cancer specimens.

USP18 downregulation in peripheral blood mononuclear cells predicts nonresponse to interferon-based triple therapy in patients with chronic hepatitis C, genotype 1: a pilot study.

BACKGROUND AND AIMS: Patients with advanced liver fibrosis owing to chronic hepatitis C virus genotype 1 represent a difficult-to-treat group even if a protease inhibitor is added to pegylated interferon alpha and ribavirin. Therefore, only patients with a high chance of cure should be treated with interferon-based treatment. PATIENTS AND METHODS: Expression of IFNG, IFNLR1, and interferon-sensitive genes CXCL9, IFI16, IFI27, ISG15, and USP18 in peripheral blood mononuclear cells was assessed before and during the initial 12 weeks of treatment. The studied group consisted of 26 treatment-experienced patients of average age of 50 years with advanced liver fibrosis compared to seven healthy volunteers. Fourteen patients were treated with pegylated interferon alpha 2b, ribavirin, and boceprevir and 12 patients with telaprevir. The overall sustained virological response (SVR) rate was 69% (18/26). RESULTS: A significant difference in the initial expression (median, interquartile range [IQR]) of CXCL9 2.9×, IQR: 1.7-12.4 vs 1.2×, IQR: 0.5-1.8; (P=0.01) IFNG 7.3×, IQR: 1.7-32.6 vs 0.7×, IQR: 0.4-1.3; P=0.002 and USP18 3.7×, IQR: 2.1-7.7 vs 1.4×, IQR: 0.9-1.6; (P=0.03) was found between the SVR and non-SVR groups. Expression of all analyzed genes was progressively increasing during the first 12 weeks of therapy, but a significant difference between SVR and non-SVR group was found only in USP18 expression at week 12 (P=0.001). Initial expression of four genes predicted SVR in univariate analysis (CXCL9 [OR: 12.00, 95% CI: 1.21-118.89], IFI27 [OR: 12.00, 95% CI: 1.21-118.89], IFNG [OR: 10.50, 95% CI: 1.50-73.67], USP18 [OR: 21.00, 95% CI: 2.05-215.18]). In multivariate analysis, only the initial expression of USP18 was identified as a predictor of SVR (P=0.047). CONCLUSION: Initial expression of USP18 and the course of its activation could be a reliable predictor of SVR achievement.