Neonatal hemochromatosis (NH) is characterized by hepatic failure in the newborn period and heavy iron staining in the liver. In addition, there is marked siderosis of extrahepatic tissues, including the heart and pancreas (Driscoll et al., 1988). Whitington (2007) postulated that some cases of neonatal hemochromatosis result from maternal alloimmunity directed at the fetal liver, and therefore do not represent an inherited mendelian disorder. Other causes may result from metabolic disease or perinatal infection. In particular, he commented that the disorder is not related to the family of inherited liver diseases that fall under the classification of hereditary hemochromatosis (see, e.g., 235200). Whitington (2007) proposed the term 'congenital alloimmune hepatitis.' In the past, the disorder has loosely been labeled 'neonatal hepatitis' and 'giant cell hepatitis,' which are pathologic findings in the liver representing a common response to a variety of insults, including cholestatic disorders and infection, among others (Fawaz et al., 1975; Knisely et al., 1987; Kelly et al., 2001).

TFR2-related hereditary hemochromatosis (TFR2-HHC) is characterized by increased intestinal iron absorption resulting in iron accumulation in the liver, heart, pancreas, and endocrine organs. Age of onset is earlier than in HFE-HHC. The majority of individuals present with signs and symptoms of iron overload in the third decade (e.g., weakness, fatigue, abdominal pain, hepatomegaly, arthritis, arthralgia, progressive increase in skin pigmentation). Others present as young adults with nonspecific symptoms and abnormal serum iron studies or as adults with abnormal serum iron studies and signs of organ involvement including cirrhosis, diabetes mellitus, and arthropathy.

GRACILE syndrome is a severe disorder that begins before birth. GRACILE stands for the condition's characteristic features: growth retardation, aminoaciduria, cholestasis, iron overload, lactic acidosis, and early death.\n\nIn GRACILE syndrome, growth before birth is slow (intrauterine growth retardation). Affected newborns are smaller than average and have an inability to grow and gain weight at the expected rate (failure to thrive). A characteristic of GRACILE syndrome is excess iron in the liver, which likely begins before birth. Iron levels may begin to improve after birth, although they typically remain elevated. Within the first day of life, infants with GRACILE syndrome have a buildup of a chemical called lactic acid in the body (lactic acidosis). They also have kidney problems that lead to an excess of molecules called amino acids in the urine (aminoaciduria). Babies with GRACILE syndrome have cholestasis, which is a reduced ability to produce and release a digestive fluid called bile. Cholestasis leads to irreversible liver disease (cirrhosis) in the first few months of life.\n\nBecause of the severe health problems caused by GRACILE syndrome, infants with this condition do not survive for more than a few months, and about half die within a few days of birth.

Juvenile hemochromatosis is characterized by onset of severe iron overload occurring typically in the first to third decades of life. Males and females are equally affected. Prominent clinical features include hypogonadotropic hypogonadism, cardiomyopathy, glucose intolerance and diabetes, arthropathy, and liver fibrosis or cirrhosis. Hepatocellular cancer has been reported occasionally. The main cause of death is cardiac disease. If juvenile hemochromatosis is detected early enough and if blood is removed regularly through the process of phlebotomy to achieve iron depletion, morbidity and mortality are greatly reduced.

Juvenile hemochromatosis is characterized by onset of severe iron overload occurring typically in the first to third decades of life. Males and females are equally affected. Prominent clinical features include hypogonadotropic hypogonadism, cardiomyopathy, glucose intolerance and diabetes, arthropathy, and liver fibrosis or cirrhosis. Hepatocellular cancer has been reported occasionally. The main cause of death is cardiac disease. If juvenile hemochromatosis is detected early enough and if blood is removed regularly through the process of phlebotomy to achieve iron depletion, morbidity and mortality are greatly reduced.

HFE hemochromatosis is characterized by inappropriately high absorption of iron by the small intestinal mucosa. The phenotypic spectrum of HFE hemochromatosis includes: Persons with clinical HFE hemochromatosis, in whom manifestations of end-organ damage secondary to iron overload are present; Individuals with biochemical HFE hemochromatosis, in whom transferrin-iron saturation is increased and the only evidence of iron overload is increased serum ferritin concentration; and Non-expressing p.Cys282Tyr homozygotes, in whom neither clinical manifestations of HFE hemochromatosis nor iron overload are present. Clinical HFE hemochromatosis is characterized by excessive storage of iron in the liver, skin, pancreas, heart, joints, and anterior pituitary gland. In untreated individuals, early symptoms include: abdominal pain, weakness, lethargy, weight loss, arthralgias, diabetes mellitus; and increased risk of cirrhosis when the serum ferritin is higher than 1,000 ng/mL. Other findings may include progressive increase in skin pigmentation, congestive heart failure, and/or arrhythmias, arthritis, and hypogonadism. Clinical HFE hemochromatosis is more common in men than women.

Trichohepatoenteric syndrome (THES), generally considered to be a neonatal enteropathy, is characterized by intractable diarrhea (seen in almost all affected children), woolly hair (seen in all), intrauterine growth restriction, facial dysmorphism, and short stature. Additional findings include poorly characterized immunodeficiency, recurrent infections, skin abnormalities, and liver disease. Mild intellectual disability (ID) is seen in about 50% of affected individuals. Less common findings include congenital heart defects and platelet anomalies. To date 52 affected individuals have been reported.