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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Of more than 500 diseases or syndromes studied for HL-A markers, more than 40 are known to be associated with an allele of class I, II, or III. Seven are linked to the HL-A region: six are recessive (idiopathic hemochromatosis, C2, C4A, and C4B deficiencies, congenital and late-onset deficiencies) and one is dominant (spinocerebellar ataxia). In addition, insulin-dependent diabetes mellitus is also linked to HL-A with more than one single locus. HL-A typing is of practical interest for diagnosis of ankylosing spondylitis by B27 antigen determination and for prevention of idiopathic hemochromatosis by genotyping of siblings of the index case. Prenatal diagnosis of 21-OH deficiency by genotyping fetal cells permits genetic counseling. Indeed, the discovery of the relationship between HL-A and disease can be considered a new approach to medical genetics. Extensive use of HL-A technology will probably allow better prediction of risk and may elucidate the mechanisms of certain diseases. For the first time the study of one single immunogenetic system may have a significant effect on public health through the possibility of wide-scale prevention.
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PMID:HL-A and disease. 300 51

Relatively high frequencies of some rare inherited disorders can be found in the Saguenay Region (Quebec). To understand this phenomenon, a research project on the 17th-century founder effect that led to the formation of French Canadians' gene pool is being carried out. The focus of this study is on founders who contributed to the Saguenay gene pool and who are related to contemporary probands suffering from any one of five hereditary diseases: cystic fibrosis, tyrosinemia, hemochromatosis, Charlevoix-Saguenay spastic ataxia, and sensorimotor polyneuropathia with or without agenesis of the corpus callosum. A control group has been added for comparison purposes. Altogether, 545 ascending genealogies have been reconstructed, using the Interuniversity Institute for Population Research's RETRO database, leading to > 2,500 founders. The genetic contribution of each founder to each group has been measured. Results show that (1) nearly 80% of the individuals' gene pool come from founders who settled in Nouvelle-France in the 17th century, whatever the group; (2) 15% of the founders explain 90% of the total genetic contribution of the founders, but this pattern varies from one group to another; (3) there is no subgroup of founders more related to any given group of individuals.
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PMID:Variability of the genetic contribution of Quebec population founders associated to some deleterious genes. 771 8

Remarkable progress is being made in understanding the molecular basis of disorders of human iron metabolism. Recent work has uncovered unanticipated relationships with the immune and nervous systems, intricate interconnections with copper metabolism, and striking homologies between yeast and human genes involved in the transport of transition metals. This review examines the clinical consequences of new insights into the pathophysiology of genetic abnormalities affecting iron metabolism. The proteins recently found to be involved in the absorption, transport, utilization, and storage of iron are briefly described, and the clinical manifestations of genetic disorders that affect these proteins are discussed. This chapter considers the most common inherited disorder in individuals of European ancestry (hereditary hemochromatosis), a widespread disease in sub-Saharan populations for which the genetic basis is still uncertain (African dietary iron overload), and several less frequent or rare disorders (juvenile hemochromatosis, atransferrinemia, aceruloplasminemia, hyperferritinemia with autosomal dominant congenital cataract, Friedreich's ataxia, and X-linked sideroblastic anemia with ataxia).
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PMID:Genetic disorders affecting proteins of iron metabolism: clinical implications. 1077 76

Iron is a vitally important element in mammalian metabolism because of its unsurpassed versatility as a biologic catalyst. However, when not appropriately shielded or when present in excess, iron plays a key role in the formation of extremely toxic oxygen radicals, which ultimately cause peroxidative damage to vital cell structures. Organisms are equipped with specific proteins designed for iron acquisition, export, transport, and storage as well as with sophisticated mechanisms that maintain the intracellular labile iron pool at an appropriate level. These systems normally tightly control iron homeostasis but their failure can lead to iron deficiency or iron overload and their clinical consequences. This review describes several rare iron loading conditions caused by genetic defects in some of the proteins involved in iron metabolism. A dramatic decrease in the synthesis of the plasma iron transport protein, transferrin, leads to a massive accumulation of iron in nonhematopoietic tissues but virtually no iron is available for erythropoiesis. Humans and mice with hypotransferrinemia have a remarkably similar phenotype. Homozygous defects in a recently identified gene encoding transferrin receptor 2 lead to iron overload (hemochromatosis type 3) with symptoms similar to those seen in patients with HFE-associated hereditary hemochromatosis (hemochromatosis type 1). Transferrin receptor 2 is primarily expressed in the liver but it is unclear how mutant forms cause iron overload. Mutations in the gene encoding the iron exporter, ferroportin 1, cause iron overload characterized by iron accumulation in macrophages yet normal plasma iron levels. Plasma iron, together with dominant inheritance, discriminates iron overload due to ferroportin mutations (hemochromatosis type 4) from hemochromatosis type 1. Heme oxygenase 1 is essential for the catabolism of heme and in the recycling of hemoglobin iron in macrophages. Homozygous heme oxygenase 1 deletion in mice leads to a paradoxical accumulation of nonheme iron in macrophages, hepatocytes, and many other cells and is associated with low plasma iron levels, anemia, endothelial cell damage, and decreased resistance to oxidative stress. A similar phenotype occurred in a child with severe heme oxygenase 1 deficiency. Recently, a mutation in the L-subunit of ferritin has been described that causes the formation of aberrant L-ferritin with an altered C-terminus. Individuals with this mutation in one allele of L-ferritin have abnormal aggregates of ferritin and iron in the brain, primarily in the globus pallidus. Patients with this dominantly inherited late-onset disease present with symptoms of extrapyramidal dysfunction. Mice with a targeted disruption of a gene for iron regulatory protein 2 (IRP2), a translational repressor of ferritin, misregulate iron metabolism in the intestinal mucosa and the central nervous system. Significant amounts of ferritin and iron accumulate in white matter tracts and nuclei, and adult IRP2-deficient mice develop a movement disorder consisting of ataxia, bradykinesia, and tremor. Mutations in the frataxin gene are responsible for Friedreich ataxia, the most common of the inherited ataxias. Frataxin appears to regulate mitochondrial iron (or iron-sulfur cluster) export and the neurologic and cardiac manifestations of Friedreich ataxia are due to iron-mediated mitochondrial toxicity. Finally, patients with Hallervorden-Spatz syndrome, an autosomal recessive, progressive neurodegenerative disorder, have mutations in a novel pantothenate kinase gene (PANK2). The cardinal feature of this extrapyramidal disease is pathologic iron accumulation in the globus pallidus. The defect in PANK2 is predicted to cause the accumulation of cysteine, which binds iron and causes oxidative stress in the iron-rich globus pallidus.
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PMID:Rare causes of hereditary iron overload. 1238