Inherited metabolic diseases of the liver

Pediatric metabolic liver diseases: Evolving role of liver transplantation

Metabolic liver diseases (MLD) are the second most common indication for liver transplantation (LT) in children. This is based on the fact that the majority of enzymes involved in various metabolic pathways are present within the liver and LT can cure or at least control the disease manifestation. LT is also performed in metabolic disorders for end-stage liver disease, its sequelae including hepatocellular cancer. It is also performed for preventing metabolic crisis’, arresting progression of neurological dysfunction with a potential to reverse symptoms in some cases and for preventing damage to end organs like kidneys as in the case of primary hyperoxalosis and methyl malonic acidemia. Pathological findings in explant liver with patients with metabolic disease include unremarkable liver to steatosis, cholestasis, inflammation, variable amount of fibrosis, and cirrhosis. The outcome of LT in metabolic disorders is excellent except for patients with mitochondrial disorders where significant extrahepatic involvement leads to poor outcomes and hence considered a contraindication for LT. A major advantage of LT is that in the post-operative period most patients can discontinue the special formula which they were having prior to the transplant and this increases their well-being and improves growth parameters. Auxiliary partial orthotopic LT has been described for patients with noncirrhotic MLD where a segmental graft is implanted in an orthotopic position after partial resection of the native liver. The retained native liver can be the potential target for future gene therapy when it becomes a clinical reality.

Accurate Measurement of Copper Overload in an Experimental Model of Wilson Disease by Laser Ablation Inductively Coupled Plasma Mass Spectrometry

Wilson disease is a rare inherited autosomal recessive disorder. As a consequence of genetic alterations in the ATP7B gene, copper begins to accumulate in the body, particularly in the liver and brain. Affected persons are prone to develop liver cancer and severe psychiatric and neurological symptoms. Clinically, the development of corneal Kayser-Fleischer rings and low ceruloplasmin concentrations (<20 mg/dL) are indicative of Wilson disease. However, the detection of elevated hepatic copper content (>250 µg/g dry weight) alone is still considered as the best but not exclusive diagnostic test for Wilson disease. Presently, specific copper stains (e.g., rhodanine) or indirect staining for copper-associated proteins (e.g., orcein) are widely used to histochemically visualize hepatic copper deposits. However, these procedures only detect lysosomal copper, while cytosolic copper is not detectable. Similarly, elemental analysis in scanning electron microscope with energy dispersive X-ray analysis (EDX) often leads to false negative results and inconsistencies. Here, we tested the diagnostic potential of laser ablation inductively-coupled mass spectrometry (LA-ICP-MS) that allows quantitative analysis of multiple elements. Comparative studies were performed in wild type and the Atp7b null mouse model. We propose LA-ICP-MS as a versatile and powerful method for the accurate determination of hepatic copper in people with Wilson disease with high spatial resolution.

Diagnostic histochemistry in hepatic pathology

Histochemistry has an important, continuing role in the current assessment of hepatic biopsies and resection specimens. The evaluation of connective tissue elements in the liver can be accomplished with such methods as the Masson trichrome, Snook reticulin, Vierhoff van Gieson, orcein, and Victoria blue stains. The results contribute to the diagnosis of acute and chronic hepatitis, submassive necrosis, venous outflow obstruction, steatohepatitis, and cirrhosis. Fat stains done on frozen sections of liver tissue are routinely performed in the evaluation of donor liver allograft biopsies. Iron stains such as Perls' method and the Prussian blue technique contribute to the recognition of hemochromatosis and hemosiderosis. The rhodanine, orcein, and Timm stains for copper are used in the characterization of chronic cholestatic liver disease and Wilson's disease. Labeling of carbohydrate-based moieties in various disorders is accomplished with the digested and undigested periodic acid-Schiff method, and Congo red or crystal violet stains can be employed to detect amyloid deposition. Lastly, evaluations of the thickness of the cell plates and continuity of the reticulin framework, as seen with the Snook reticulin stain, can contribute to the diagnostic separation of benign from malignant hepatocellular neoplasms.

Bartonella henselae AS A PUTATIVE CAUSE OF CONGENITAL CHOLESTASIS

Severe anemia and cholestatic hepatitis are associated with bartonella infections. A putative vertical Bartonella henselae infection was defined on the basis of ultrastructural and molecular analyses in a three-year-old child with anemia, jaundice and hepatosplenomegaly since birth. Physicians should consider bartonellosis in patients with anemia and hepatitis of unknown origin.

Zebrafish: an important tool for liver disease research

As the incidence of hepatobiliary diseases increases, we must improve our understanding of the molecular, cellular, and physiological factors that contribute to the pathogenesis of liver disease. Animal models help us identify disease mechanisms that might be targeted therapeutically. Zebrafish (Danio rerio) have traditionally been used to study embryonic development but are also important to the study of liver disease. Zebrafish embryos develop rapidly; all of their digestive organs are mature in larvae by 5 days of age. At this stage, they can develop hepatobiliary diseases caused by developmental defects or toxin- or ethanol-induced injury and manifest premalignant changes within weeks. Zebrafish are similar to humans in hepatic cellular composition, function, signaling, and response to injury as well as the cellular processes that mediate liver diseases. Genes are highly conserved between humans and zebrafish, making them a useful system to study the basic mechanisms of liver disease. We can perform genetic screens to identify novel genes involved in specific disease processes and chemical screens to identify pathways and compounds that act on specific processes. We review how studies of zebrafish have advanced our understanding of inherited and acquired liver diseases as well as liver cancer and regeneration.

Liver tumors in children with metabolic disorders

Hepatic neoplasia is a rare but serious complication of metabolic diseases in children. The risk of developing neoplasia, the age at onset, and the measures to prevent it differ in the various diseases. We review the most common metabolic disorders that are associated with a heightened risk of developing hepatocellular neoplasms, with a special emphasis on reviewing recent advances in the molecular pathogenesis of the disorders and pre-clinical therapeutic options. The cellular and genetic pathways driving carcinogenesis are poorly understood, but best understood in tyrosinemia.

Analyzing the Impact of Increasing Mechanical Index and Energy Deposition on Shear Wave Speed Reconstruction in Human Liver

Shear wave elasticity imaging (SWEI) has found success in liver fibrosis staging. This work evaluates hepatic SWEI measurement success as a function of push pulse energy using two mechanical index (MI) values (1.6 and 2.2) over a range of pulse durations. Shear wave speed (SWS) was measured in the livers of 26 study subjects with known or potential chronic liver diseases. Each measurement consisted of eight SWEI sequences, each with different push energy configurations. The rate of successful SWS estimation was linearly proportional to the push energy. SWEI measurements with higher push energy were successful in patients for whom standard push energy levels failed. The findings also suggest that liver capsule depth could be used prospectively to identify patients who would benefit from elevated output. We conclude that there is clinical benefit to using elevated acoustic output for hepatic SWS measurement in patients with deeper livers.

Hepatic neoplasia and metabolic diseases in children

Hepatic neoplasia is a rare but serious complication of metabolic diseases in children. The risk of developing neoplasia, the age at onset, and the measures to prevent it differ in various diseases. This article reviews the most common metabolic disorders in humans that are associated with neoplasms, with a special emphasis on the molecular etiopathogenesis of this process. The cellular pathways driving carcinogenesis are poorly understood, but best known in tyrosinemia.

[Cholestasis-associated hepatopathies in neonates and infants]

Cholestasis in neonates and infants frequently confronts pediatricians and pathologists with diagnostic problems. A specific feature of the liver in neonates is the ability to react to different causative factors with a non-specific hepatitis-like picture, the so-called neonatal hepatitis. A diagnostic discrimination of the various diseases is histologically only possible with close attention to typical morphologic features. Thus, extrahepatic biliary obstructions, such as atresia or stenosis of the hepatic duct or choledochal cysts present with portal bile duct proliferation and signs of bile retention in the neoducts. In Alagille syndrome (arteriohepatic dysplasia), however, paucity of intrahepatic bile ducts is an important diagnostic feature. Metabolic disorders, such as fructosemia and galactosemia are additionally associated with steatosis. Knowledge of the clinical course and laboratory and imaging data are necessary to make the definitive diagnosis in synopsis with the morphologic findings and requires a close co-operation between the pediatrician and the pathologist.

Pathology teach and tell: fibrinogen storage disease in a child with hypofibrinogenemia and decreased ceruloplasmin

The authors present a clinical case of a patient with mild liver disease and coagulopathy. The diagnosis was reached through careful histologic examination of liver biopsy. Electron microscopy played an important role in confirming the diagnosis.

N/A

N/A

Biliary atresia

BA is a rare disease of unclear etiology; nevertheless, its impact in the field of pediatric hepatology is significant. It is the most common surgically correctable cause of neonatal cholestasis and is the most common pediatric disease referred for liver transplantation. Little progress has been made with regard to improving outcome or understanding its pathogenesis in the past decade. Fortunately, however, a national, government-sponsored collaborative endeavor has begun that will hopefully make a significant impact upon the progress of designing new treatments for BA and develop a better understanding of its pathogenesis.