Wilson Disease Prevalence: Discrepancy Between Clinical Records, Registries and Mutation Carrier Frequency.

OBJECTIVES: Diagnosis of Wilson disease (WD) is difficult and, as early detection may prevent all symptoms, it is essential to know the exact prevalence to evaluate the cost-efficacy of a screening program. As the number of WD patients was high in our population, we wished to estimate prevalence by determining the carrier frequency for clinically relevant ATP7B mutations. METHODS: To estimate prevalence, screening for the most prevalent mutation was performed in 1661 individuals with ancestry in Gran Canaria, and the frequency of other mutations was estimated from patient records. Alternatively, ATP7B mutations were detected from exomes and genomes from 851 individuals with Canarian ancestry, 236 from Gran Canaria, and a public Spanish exome database. RESULTS: Estimated carrier frequencies in Gran Canaria ranged from 1 in 20 to 28, depending on the method used, resulting in prevalences of 1 case per 1547 to 3140 inhabitants. Alternatively, the estimated affected frequencies were 1 in 5985 to 7980 and 1 in 6278 to 16,510 in the archipelago or mainland Spain respectively. CONCLUSIONS: The number of carriers predicts much higher prevalences than reported, suggesting that WD is underdiagnosed; specific mutations may remain unnoticed due to low penetrance or no signs of disease at all; regional prevalence rather than national prevalence should be considered in cost-efficacy models to approach preventive screening in the asymptomatic population and genetic screening strategies will have to deal with the genetic heterogeneity of ATP7B in the general population and in patients.

Profile of plasma microRNAs as a potential biomarker of Wilson's disease.

BACKGROUND: Wilson's disease (WD) is a rare condition resulting from autosomal recessive mutations in ATP7B, a copper transporter, manifesting with hepatic, neurological, and psychiatric symptoms. Timely diagnosis and appropriate treatment yield a positive prognosis, while delayed identification and/or insufficient therapy lead to a poor outcome. Our aim was to establish a prognostic method for WD by characterising biomarkers based on circulating microRNAs. METHODS: We conducted investigations across three cohorts: discovery, validation (comprising unrelated patients), and follow-up (revisiting the discovery cohort 3 years later). All groups were compared to age- and gender-matched controls. Plasma microRNAs were analysed via RNA sequencing in the discovery cohort and subsequently validated using quantitative PCR in all three cohorts. To assess disease progression, we examined the microRNA profile in Atp7b-/- mice, analysing serum samples from 6 to 44 weeks of age and liver samples at three time points: 20, 30, and 40 weeks of age. RESULTS: In patients, elevated levels of the signature microRNAs (miR-122-5p, miR-192-5p, and miR-885-5p) correlated with serum activities of aspartate transaminase, alanine aminotransferase and gamma-glutamyl transferase. In Atp7b-/- mice, levels of miR-122-5p and miR-192-5p (miR-885-5p lacking a murine orthologue) increased from 12 weeks of age in serum, while exhibiting fluctuations in the liver, possibly attributable to hepatocyte regenerative capacity post-injury and the release of hepatic microRNAs into the bloodstream. CONCLUSIONS: The upregulation of the signature miR-122-5p, miR-192-5p, and miR-885-5p in patients and their correlation with liver disease progression in WD mice support their potential as biomarkers of WD.

Low penetrance of frequent ATP7B mutations explains the low prevalence of Wilson disease. Lessons from real-life registries.

BACKGROUND & AIMS: Wilson disease (WD) is a copper metabolism disorder caused by mutations in ATP7B gene, with significant clinical variability. Several studies have analyzed the prevalence and penetrance of mutations. We evaluated both characteristics for our more frequent mutations. METHODS: Evaluation of 260 patients from the National Registry: clinical, analytical and genetic data. Estimation of homozygotes and total cases according to Hardy-Weinberg equilibrium and comparison with Registry records. RESULTS: The estimated number of homozygotes were higher than registered: p.Met645Arg (1949/6), p.His1069Gln (20/8), p.Leu708Pro (63/24) and p.Gly869Arg (147/0). p.Met645Arg homozygotes presented less cirrhosis at diagnosis, extrahepatic disease and Kayser-Fleischer ring (KFR) and more presymptomatic cases and diagnosis after 40 years of age than p.Leu708Pro and p.His1069Gln homozygotes. p.Met645Arg homozygotes presented more late diagnosis than p.Met645Arg compound heterozygotes. Compound heterozygotes carrying p.Met645Arg or p.Gly869Arg showed less cirrhosis at diagnosis, KFR and neurological symptoms and more hepatic and presymptomatic cases, despite clearly low ceruloplasmin levels. The estimated prevalence was 1:3.785, predicting more than 10.500 patients. CONCLUSIONS: The widespread mutations p.Met645Arg and p.Gly869Arg show low penetrance. WD might be underdiagnosed in Spain due to less severe phenotype of the most frequent mutations, a crucial fact to avoid misdiagnosis and to offer early therapy.

Massive spontaneous portosystemic shunt is a solid, easily identifiable prognostic factor in patients with cirrhosis.

OBJECTIVES: Spontaneous portosystemic shunts (SPSSs) are associated with complications and death in cirrhosis. We evaluated chronic portosystemic encephalopathy (CPSE) and survival in cirrhotic patients with massive (>10 mm diameter) SPSS (MSPSS). METHODS: We have retrospectively compared 77 cirrhotic patients with MSPSS and 77 paired-matched patients without SPSS. RESULTS: More patients with MSPSS presented with CPSE (40.3% vs. 20.8%, P = 0.010) or died (33.8% vs. 18.2%, P = 0.039). Model for Endstage Liver Disease (MELD) score [hazard ratio (HR) 1.146, 95% confidence interval (CI) 1.099-1.195], follow-up (FU) ascites (HR 5.128, 95% CI 2.396-10.973) and age (HR 1.048, 95% CI 1.017-1.080) were associated with CPSE; and MELD score (HR 1.082, 95% CI 1.035-1.131), FU renal failure (HR 9.319, 95% CI 3.595-24.158), and FU ascites (HR 4.320, 95% CI 1.615-11.555) were associated with death. Liver function worsened faster in the MSPSS group. Among patients with better liver function (MELD < 11.5), MSPSS patients presented worse survival (P = 0.048, Breslow test). Comparing patients by the Child-Pugh group, we did not find differences in survival; in patients from Child-Pugh group B + C, the MSPSS group presented less time free of CPSE (P < 0.05, log-rank test). Patients with splenorenal MSPSS presented better survival (P = 0.04, log-rank test), and patients with umbilical MSPSS had shorter time free of CPSE (P < 0.016, log-rank test). CONCLUSION: MSPSS increased CPSE and death risks during long FU. Even with better liver function (MELD < 11.5), MSPSS was associated with lower survival. Splenorenal MSPSS presented better survival and the umbilical type was associated with shorter time free of CPSE.

Manifestations and evolution of Wilson disease in pediatric patients carrying ATP7B mutation L708P.

OBJECTIVES: The aim of the study was to characterize a group of 11 pediatric patients, ages 3 to 13 years, affected by Wilson disease (WD) in the island of Gran Canaria, Spain. PATIENTS AND METHODS: Genetic, biochemical, and pathological features, together with their response to treatment and clinical evolution, have been analyzed for this group of patients. RESULTS: Genetically, the group was rather homogeneous, with an extremely high prevalence of the L708P mutation (4 homozygotes and 5 heterozygotes). Despite being initially screened because of asymptomatic hypertransaminemia, all of the patients presented with some degree of liver damage that was never accompanied by any neurological manifestation. Hepatic damage was most severe in a compound heterozygote with a novel mutation, G1266W, affecting a motif in the ATP7B polypeptide that is greatly conserved in similar proteins among metazoans. Ceruloplasmin and copper serum levels, together with the determination of hepatic copper content, were found to be of great diagnostic value, whereas urine copper measurements were found to be much less conclusive. All of the patients responded well to treatment with D-penicillamine with no documented adverse reactions. CONCLUSIONS: The patients in Gran Canaria constitute, overall, one of the largest groups of patients with WD with a high incidence of a single mutation, allowing us to define the early clinical symptoms and the evolution of the disease in patients carrying the ATP7B L708P mutant allele, and the study of WD in a genetically homogeneous background.

Wilson disease: revision of diagnostic criteria in a clinical series with great genetic homogeneity.

BACKGROUND: Wilson disease is an autosomal recessive disorder of copper metabolism caused by mutations in the ATP7B gene. An early diagnosis is crucial to prevent evolution of the disease, as implantation of early therapeutic measures fully prevents its symptoms. As population genetics data predict a higher than initially expected prevalence, it was important to define the basic diagnostic tools to approach population screening. METHODS: A highly genetically homogeneous cohort of 70 patients, belonging to 50 unrelated families, has been selected as a framework to analyze all their clinical, biochemical and genetic characteristics, to define the disease in our population, with an estimated prevalence of 1 in 12,369, and determine the most useful features that reach diagnostic value. RESULTS: Serum ceruloplasmin below 11.5 mg/dL and cupremia below 60 µg/mL, were the best analytical predictors of the disease in asymptomatic individuals, while cupruria or hepatic copper determination were less powerful. Genetic analysis reached a conclusive diagnosis in all 65 patients available for complete testing. Of them, 48 were carriers of at least one p.Leu708Pro mutant allele, with 24 homozygotes. Nine patients carried a promoter deletion mutation, revealing that extended sequencing beyond the ATP7B gene-coding region is essential. All mutations caused hepatic damage since early ages, increasing its severity as diagnosis was delayed, and neurological symptoms appear. CONCLUSION: Serum ceruloplasmin determination followed by genetic screening would reduce costs and favor the prioritization of non-invasive procedures to reach a definitive diagnosis, even for asymptomatic cases.

Methodological characterization of the 2-keto [1-13C]isocaproate breath test to measure in vivo human mitochondrial function: application in alcoholic liver disease assessment.

BACKGROUND: The 2-keto[1-13C]isocaproate oxidation measurement has been shown as a helpful tool in the in vivo assessment of liver mitochondrial function. METHODS: The aim of this work was to study the variability of the 2-keto[1-13C]isocaproate breath test in 24 healthy controls (8 men and 16 women) and to evaluate its clinical usefulness in 20 patients (14 men and 6 women) with liver disease (7 men with history of alcoholism). Breath test was performed by measuring 13CO2 enrichment in breath before and after the oral administration of the tracer and by using isotope ratio mass spectrometry. RESULTS: The intrasubject and intersubject variability of the percentage of tracer oxidized were 8 and 14%, respectively. The 2-keto[1-13C]isocaproate oxidation in women was faster (p = 0.004) and tended to be higher (p = 0.050) than in men. The percentage of oxidized tracer was lower in those patients with alcoholic liver disease than in healthy volunteers (p = 0.001) and in nonalcoholic patients (p = 0.003). CONCLUSIONS: The percentage of tracer oxidized appears as a convenient parameter to detect impairment in liver mitochondrial oxidation related to alcoholism by the 2-keto[1-13C]isocaproate breath test, establishing different cutoff values depending on gender.