Advances in the understanding of cobalamin assimilation and metabolism

Abstract

SummaryThe haematological and neurological consequences of cobalamin deficiency define the essential role of this vitamin in key metabolic reactions. The identification of cubilin-amnionless as the receptors for intestinal absorption of intrinsic factorbound cobalamin and the plasma membrane receptor for cellular uptake of transcobalamin bound cobalamin have provided a clearer understanding of the absorption and cellular uptake of this vitamin. As the genes involved in the intracellular processing of cobalamins and genetic defects of these pathways are identified, the metabolic disposition of cobalamins and the proteins involved are being recognized. The synthesis of methylcobalamin and 5¢-deoxyadenosylcobalamin, their utilization in conjunction with methionine synthase and methylmalonylCoA mutase, respectively, and the metabolic consequences of defects in these pathways could provide insights into the clinical presentation of cobalamin deficiency.

Association between metformin and vitamin B12 deficiency in patients with type 2 diabetes: A systematic review and meta-analysis

“…pernicious anaemia) can result in macrocytic anaemia, peripheral neuropathy and mental-psychiatric changes. Also, milder symptoms such as weakness, tiredness, and memory loss can occur before frank anaemia [5][6][7].Metformin-related vitamin B12 deficiency has been known for over 40 years. However, a systematic analysis of the data concerning B12 status and metformin usage has not been carried out to date specifically in patients with Type 2 Diabetes.…”

Expanding the Spectrum of Methylmalonic Acid-Induced Pallidal Stroke: First Reported Case of Metabolic Globus Pallidus Stroke in Transcobalamin II Deficiency

“…It binds and transports cobalamin absorbed in the terminal ileum to tissue cells throughout the body, where it ultimately participates in cell surface adhesion and internalization of the cobalamin (Quadros 2009). TCII is also synthesized by astrocytes and is the primary enzyme involved in the neuronal uptake of cobalamin in the central nervous system (Begley et al 1994).…”

Carence en vitamine B12 (1repartie) : mise au point

“…Chez l'adulte, les étiologies de la carence en vitamine B12 sont par ordre de fréquence décroissant (Fig. 4) [66]. Fig.…”

“…3. Vitamin B12 mtabolism: involved proteins in the absorption process and identified acquired or congenital defects [66].…”