Excess copper in the liver is toxic in humans and other mammals, and may lead to acute or chronic hepatitis, steatohepatitis, acute liver failure, cirrhosis and death. Of the several human copper storage diseases that have been described, the molecular basis of only Wilson disease is understood with the discovery of the Wilson disease gene (ATP7B) in 1993. The therapeutic success using oral copper chelating agents and zinc therapy make Wilson disease one of the few treatable genetic metabolic liver diseases. In cases with a fulminant presentation or advanced disease at diagnosis, copper chelation is ineffective and liver transplantation may be lifesaving. Indian Childhood Cirrhosis (ICC) has been defined as a copper-storage disorder precipitated by increased copper intake which affects young children primarily of Indian descent, and which progresses to cirrhosis and death before age three to four years without treatment. Children from North America, Asia, Austria, Germany and other countries have been described with a similar condition, which has been termed idiopathic copper toxicosis (ICT). Several newer disorders of hepatic copper metabolism have been recently described.

When first encountering an infant or child with cholestatic liver disease, it is essential that diagnostic evaluation be conducted promptly in order to recognize disorders amenable either to specific medical therapy (e.g., galactosemia, tyrosinemia, hypothyroidism, urinary tract infection) or to early surgical intervention (e.g., biliary atresia, choledochal cyst); institute treatment directed toward enhancing bile flow; and prevent and treat the varied medical, nutritional, and emotional consequences of chronic liver disease.

Intestinal failure (IF) is defined as the end result of any gastrointestinal disorder in which functional intestinal mass is insufficient to allow adequate growth, hydration, and electrolyte balance in children and adults. Inherent in this definition is the requirement for parental nutrition (PN), which is provided to maintain fluid, energy, protein, electrolyte, and micronutrient delivery in the absence of adequate intestinal function. In the pediatric population, IF may be the end result of various primary etiologies, although the most common is short bowel syndrome (SBS) following congenital or acquired disorders, including necrotizing enterocolitis (NEC), small intestinal atresia, volvulus, and gastroschisis. Table 15.1 summarizes the most common etiologies of pediatric IF.

Pathologies of mitochondrial structure and function are now recognized as the etiology of a growing list of monogenic mitochondrial disorders as well as contributing to many common diseases. Studying patients with respiratory chain disorders has contributed much to our current knowledge about mitochondrial biology [1]. Mutations impacting mitochondrial proteins as well as ribosomal and transfer RNAs (tRNAs) are the underlying cause of diseases affecting the nervous system, skeletal and cardiac muscle, the liver, bone marrow, the endocrine and exocrine pancreas, kidney, inner ear and small and large intestines (Table 35.1) [1]. Perturbations in mitochondrial function result in defective oxidative phosphorylation (OXPHOS) and ATP generation, increased generation of reactive oxygen species (ROS), accumulation of hepatocytic lipid, impairment of other mitochondria-based metabolic processes and activation of apoptotic, autophagic and necrotic cell death pathways [2]. The spectrum of genetic etiologies of inherited mitochondrial hepatic and gastrointestinal disorders continues to expand. In addition, mitochondrial dysfunction may be one of the key determinants of hepatocyte survival in other disorders that are not monogenic mitochondrial diseases. Thus, the concept of primary (or genetic) and secondary (or acquired) mitochondrial hepatopathies has developed.