MedGen

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. [from GeneReviews]

Aceruloplasminemia is characterized by iron accumulation in the brain and viscera. The clinical triad of retinal degeneration, diabetes mellitus (DM), and neurologic disease is seen in individuals ranging from age 30 years to older than 70 years. The neurologic findings of movement disorder (blepharospasm, grimacing, facial and neck dystonia, tremors, chorea) and ataxia (gait ataxia, dysarthria) correspond to regions of iron deposition in the brain. Individuals with aceruloplasminemia often present with anemia prior to onset of DM or obvious neurologic problems. Cognitive dysfunction including apathy and forgetfulness occurs in more than half of individuals with this condition. [from GeneReviews]

Lysinuric protein intolerance (LPI) typically presents after an infant is weaned from breast milk or formula; variable findings include recurrent vomiting and episodes of diarrhea, episodes of stupor and coma after a protein-rich meal, poor feeding, aversion to protein-rich food, failure to thrive, hepatosplenomegaly, and muscular hypotonia. Over time, findings include: poor growth, osteoporosis, involvement of the lungs (progressive interstitial changes, pulmonary alveolar proteinosis) and of the kidneys (progressive glomerular and proximal tubular disease), hematologic abnormalities (normochromic or hypochromic anemia, leukopenia, thrombocytopenia, erythroblastophagocytosis in the bone marrow aspirate), and a clinical presentation resembling the hemophagocytic lymphohistiocytosis/macrophagic activation syndrome. Hypercholesterolemia, hypertriglyceridemia, and acute pancreatitis can also be seen. [from GeneReviews]

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. [from GeneReviews]

Familial hemophagocytic lymphohistiocytosis-5 with or without microvillus inclusion disease (FHL5) is an autosomal recessive hyperinflammatory disorder characterized clinically by fever, hepatosplenomegaly, pancytopenia, coagulation abnormalities, and other laboratory findings. Some patients have neurologic symptoms due to inflammatory CNS disease. There is uncontrolled and ineffective proliferation and activation of T lymphocytes, NK cells, and macrophages that infiltrate multiple organs, including liver, spleen, lymph nodes, and the CNS. The phenotype is variable: some patients may present in early infancy with severe diarrhea, prior to the onset of typical FHL features, whereas others present later in childhood and have a more protracted course without diarrhea. The early-onset diarrhea is due to enteropathy reminiscent of microvillus inclusion disease (see MVID, 251850). The enteropathy, which often necessitates parenteral feeding, may be the most life-threatening issue even after hematopoietic stem cell transplantation (HSCT). More variable features include sensorineural hearing loss and hypogammaglobulinemia. Treatment with immunosuppressive drugs and chemotherapy can ameliorate signs and symptoms of FHL in some patients, but the only curative therapy for FHL is HSCT. HSCT is not curative for enteropathy associated with the disorder, despite hematologic and immunologic reconstitution (summary by Meeths et al., 2010; Pagel et al., 2012; Stepensky et al., 2013). For a phenotypic description and a discussion of genetic heterogeneity of familial hemophagocytic lymphohistiocytosis (FHL, HLH), see 267700. [from OMIM]

X-linked lymphoproliferative disease (XLP) has two recognizable subtypes, XLP1 and XLP2. XLP1 is characterized predominantly by one of three commonly recognized phenotypes: Inappropriate immune response to Epstein-Barr virus (EBV) infection leading to hemophagocytic lymphohistiocytosis (HLH) or severe mononucleosis. Dysgammaglobulinemia. Lymphoproliferative disease (malignant lymphoma). XLP2 is most often characterized by HLH (often associated with EBV), dysgammaglobulinemia, and inflammatory bowel disease. HLH resulting from EBV infection is associated with an unregulated and exaggerated immune response with widespread proliferation of cytotoxic T cells, EBV-infected B cells, and macrophages. Dysgammaglobulinemia is typically hypogammaglobulinemia of one or more immunoglobulin subclasses. The malignant lymphomas are typically B-cell lymphomas, non-Hodgkin type, often extranodal, and in particular involving the intestine. [from GeneReviews]

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. [from GeneReviews]

Familial hemophagocytic lymphohistiocytosis-2 (FHL2) is an autosomal recessive disorder of immune dysregulation with onset in infancy or early childhood. It is characterized clinically by fever, edema, hepatosplenomegaly, and liver dysfunction. Neurologic impairment, seizures, and ataxia are frequent. Laboratory studies show pancytopenia, coagulation abnormalities, hypofibrinogenemia, and hypertriglyceridemia. There is increased production of cytokines, such as gamma-interferon (IFNG; 147570) and TNF-alpha (191160), by hyperactivation and proliferation of T cells and macrophages. Activity of cytotoxic T cells and NK cells is reduced, consistent with a defect in cellular cytotoxicity. Bone marrow, lymph nodes, spleen, and liver show features of hemophagocytosis. Chemotherapy and/or immunosuppressant therapy may result in symptomatic remission, but the disorder is fatal without bone marrow transplantation (summary by Dufourcq-Lagelouse et al., 1999, Stepp et al., 1999, and Molleran Lee et al., 2004). For a general phenotypic description and a discussion of genetic heterogeneity of FHL, see 267700. [from OMIM]

Multiple congenital anomalies-hypotonia-seizures syndrome-2 (MCAHS2) is an X-linked recessive neurodevelopmental disorder characterized by dysmorphic features, neonatal hypotonia, early-onset myoclonic seizures, and variable congenital anomalies involving the central nervous, cardiac, and urinary systems. Some affected individuals die in infancy (summary by Johnston et al., 2012). The phenotype shows clinical variability with regard to severity and extraneurologic features. However, most patients present in infancy with early-onset epileptic encephalopathy associated with developmental arrest and subsequent severe neurologic disability; these features are consistent with a form of developmental and epileptic encephalopathy (DEE) (summary by Belet et al., 2014, Kato et al., 2014). The disorder is caused by a defect in glycosylphosphatidylinositol (GPI) biosynthesis. For a discussion of genetic heterogeneity of MCAHS, see MCAHS1 (614080). For a discussion of nomenclature and genetic heterogeneity of DEE, see 308350. For a discussion of genetic heterogeneity of GPI biosynthesis defects, see GPIBD1 (610293). [from OMIM]

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. [from GeneReviews]

Familial Hemophagocytic lymphohistiocytosis (FHL) is a rare primary immunodeficiency characterized by a macrophage activation syndrome with an onset usually occurring within a few months or less common several years after birth. [from MONDO]

GRACILE syndrome is an autosomal recessive lethal disorder characterized by fetal growth retardation, lactic acidosis, aminoaciduria, cholestasis, and abnormalities in iron metabolism. Patients develop fulminant lactic acidosis during the first day of life. Despite intensive care, about half of affected infants die during the first days of life, and the remainder within 4 months of life. Finnish and British patients have been reported, with slightly different phenotypes; the British patients have additional features of complex III deficiency and neurologic symptoms (Visapaa et al., 2002). [from OMIM]

Myopathy, lactic acidosis, and sideroblastic anemia (MLASA) is a rare autosomal recessive oxidative phosphorylation disorder specific to skeletal muscle and bone marrow (Bykhovskaya et al., 2004). Genetic Heterogeneity of Myopathy, Lactic Acidosis, and Sideroblastic Anemia MLASA2 (613561) is caused by mutation in the YARS2 gene (610957) on chromosome 12p11. MLASA3 (500011) is caused by heteroplasmic mutation in the mitochondrially-encoded MTATP6 gene (516060). [from OMIM]

Hemophagocytic lymphohistiocytosis is a hyperinflammatory disorder clinically diagnosed based on the fulfillment of 5 of 8 criteria, including fever, splenomegaly, bicytopenia, hypertriglyceridemia and/or hypofibrinogenemia, hemophagocytosis, low or absent natural killer (NK) cell activity, hyperferritinemia, and high soluble IL2 receptor levels (IL2R; 147730). The disorder typically presents in infancy or early childhood. Persistent remission is rarely achieved with chemo- or immunotherapy; hematopoietic stem cell transplantation is the only cure (summary by Muller et al., 2014). For a phenotypic description and a discussion of genetic heterogeneity of familial hemophagocytic lymphohistiocytosis (FHL), see 267700. [from OMIM]

Hyperferritinemia-cataract syndrome is a disorder characterized by an excess of an iron storage protein called ferritin in the blood (hyperferritinemia) and tissues of the body. A buildup of this protein begins early in life, leading to clouding of the lenses of the eyes (cataracts). In affected individuals, cataracts usually develop in infancy, rather than after age 60 as typically occurs in the general population. Cataracts that are not removed surgically cause progressive dimming and blurriness of vision because the clouded lenses reduce and distort incoming light.

Although the hyperferritinemia in this disorder does not usually cause any health problems other than cataracts, the elevated ferritin levels in the blood can be mistaken for a sign of certain liver disorders. These conditions result in excess iron in the body and may be treated by blood-drawing. However, individuals with hyperferritinemia-cataract syndrome do not have an excess of iron, and with repeated blood draws will develop reduced iron levels leading to a low number of red blood cells (anemia). Therefore, correct diagnosis of hyperferritinemia-cataract syndrome is important to avoid unnecessary treatments or invasive test procedures such as liver biopsies. [from MedlinePlus Genetics]

Hemochromatosis type 4 (HFE4) is a dominantly inherited iron overload disorder with heterogeneous phenotypic manifestations that can be classified into 2 groups. One group is characterized by an early rise in ferritin (see 134790) levels with low to normal transferrin (190000) saturation and iron accumulation predominantly in macrophages. The other group is similar to classical hemochromatosis, with high transferrin saturation and prominent parenchymal iron loading (summary by De Domenico et al., 2005). For general background information and a discussion of genetic heterogeneity of hereditary hemochromatosis, see 235200. [from OMIM]

Most characteristically, Aicardi-Goutières syndrome (AGS) manifests as an early-onset encephalopathy that usually, but not always, results in severe intellectual and physical disability. A subgroup of infants with AGS present at birth with abnormal neurologic findings, hepatosplenomegaly, elevated liver enzymes, and thrombocytopenia, a picture highly suggestive of congenital infection. Otherwise, most affected infants present at variable times after the first few weeks of life, frequently after a period of apparently normal development. Typically, they demonstrate the subacute onset of a severe encephalopathy characterized by extreme irritability, intermittent sterile pyrexias, loss of skills, and slowing of head growth. Over time, as many as 40% develop chilblain skin lesions on the fingers, toes, and ears. It is becoming apparent that atypical, sometimes milder, cases of AGS exist, and thus the true extent of the phenotype associated with pathogenic variants in the AGS-related genes is not yet known. [from GeneReviews]

Lymphoproliferative syndrome-1 is an autosomal recessive primary immunodeficiency characterized by onset in early childhood of Epstein-Barr virus (EBV)-associated immune dysregulation, manifest as lymphoma, lymphomatoid granulomatosis, hemophagocytic lymphohistiocytosis, Hodgkin disease, and/or hypogammaglobulinemia. Autoimmune disorders, such as autoimmune hemolytic anemia or renal disease, may also occur. Patients show a high EBV viral load and decreased invariant natural killer T cells. It is unknown whether patients with ITK mutations are intrinsically susceptible to development of lymphoma or dysgammaglobulinemia in the absence of EBV infection (summary by Stepensky et al., 2011; Linka et al., 2012). For a discussion of genetic heterogeneity of lymphoproliferative syndrome, see XLP1 (308240). [from OMIM]

Sideroblastic anemia-3 is an autosomal recessive hematologic disorder characterized by onset of anemia in adulthood. Affected individuals show signs of systemic iron overload, and iron chelation therapy may be of clinical benefit (summary by Liu et al., 2014). For a discussion of genetic heterogeneity of sideroblastic anemia, see SIDBA1 (300751). [from OMIM]