Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004364 (autoimmune disease)
 24,845 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cobalamin (vitamin B12) is an essential nutrient derived exclusively from bacterial sources. It is an essential cofactor for three known enzymatic reactions. Untreated deficiency, caused by either the autoimmune disease pernicious anemia or nutritional lack, results in a macrocytic anemia and/or subacute combined degeneration of the spinal cord and is eventually fatal. Cobalamin in serum is bound to two proteins, transcobalamin and haptocorrin. The former is responsible for the essential delivery of cobalamin to most tissues. Inadequate tissue availability of cobalamin results in increased concentration of methylmalonic acid and homocyst(e)ine due to inhibition of methylmalonyl-CoA mutase and methionine synthase, respectively. Strict vegetarians have long been known to be at risk of cobalamin deficiency, which develops insidiously over many years. It is now clear that a significant number of the elderly and HIV-positive individuals are also at increased risk of deficiency. Any individual with reduced ability to split cobalamin from food-protein may also become deficient even though intrinsic factor is present. Diagnosis of cobalamin deficiency has frequently relied on total serum cobalamin and the Schilling test. Newer approaches such as analysis of methylmalonic acid, homocyst(e)ine, holotranscobalamin, anti-intrinsic factor antibodies, and serum gastrin may provide more cost-effective testing, as well as identify those with a covert deficiency.
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PMID:Cobalamin. 887 26

Vitamin B12 (cobalamin) was identified nearly 80 years ago as the anti-pernicious anaemia factor in liver, and its importance in human health and disease has resulted in much work on its uptake, cellular transport and utilization. Plants do not contain cobalamin because they have no cobalamin-dependent enzymes. Deficiencies are therefore common in strict vegetarians, and in the elderly, who are susceptible to an autoimmune disorder that prevents its efficient uptake. In contrast, many algae are rich in vitamin B12, with some species, such as Porphyra yezoensis (Nori), containing as much cobalamin as liver. Despite this, the role of the cofactor in algal metabolism remains unknown, as does the source of the vitamin for these organisms. A survey of 326 algal species revealed that 171 species require exogenous vitamin B12 for growth, implying that more than half of the algal kingdom are cobalamin auxotrophs. Here we show that the role of vitamin B12 in algal metabolism is primarily as a cofactor for vitamin B12-dependent methionine synthase, and that cobalamin auxotrophy has arisen numerous times throughout evolution, probably owing to the loss of the vitamin B12-independent form of the enzyme. The source of cobalamin seems to be bacteria, indicating an important and unsuspected symbiosis.
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PMID:Algae acquire vitamin B12 through a symbiotic relationship with bacteria. 1626 37

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by overexpression of cytokines and T cell accessory molecules, which is due to a reduction of DNA regulatory region methylation in T cells. It has been shown that polymorphic variants of genes encoding key enzymes of folate and methionine metabolism may have an effect on DNA methylation. Therefore, in patients with SLE (n = 106) and controls (n = 141) we examined the distribution of polymorphisms of genes encoding methionine synthase (MTR); 5,10-methylenetetrahydrofolate dehydrogenase, 5,10-methenyltetrahydrofolate cyclohydrolase and 10-formyltetrahydrofolate synthetase (MTHFD1); and methylenetetrahydrofolate reductase (MTHFR). We found that MTR 2756AG (919DG) or GG (919GG) genotype exhibited 2.005-fold increased risk of SLE (95% CI = 1.177-3.416, P = 0.0146). However, MTHFR 677C > T (A222V) and MTHFD1 1958G > A (R653Q) allele and genotype frequencies did not exhibit statistical differences between SLE patients and controls. Since MTR is located on 1q43, our findings confirm the significance of the role of 1q region and the methyl cycle in etiopathogenesis of SLE.
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PMID:MTR 2756 A > G polymorphism is associated with the risk of systemic lupus erythematosus in the Polish population. 1766 38