The topic Selective Vitamin B12 Malabsorption with Proteinuria you are seeking is a synonym, or alternative name, or is closely related to the medical condition Imerslund-Gräsbeck Syndrome.

Quick Summary:

• Imerslund-Gräsbeck Syndrome (IGS) is a rare genetic disorder, in which the body’s ability to absorb vitamin B12 (cobalamin) is compromised
• Vitamin B12 cannot be made by the body and can only be obtained from the food one eats. This vitamin is essential for the formation of red blood cells, and for the proper functioning of the brain and spinal cord
• Imerslund-Gräsbeck Syndrome was first described in Norway and Finland in a few families. The age of onset of IGS can range from early infancy to childhood
• It is a genetic disorder, and therefore, a family history of Imerslund-Gräsbeck Syndrome is a major risk factor for being diagnosed the disorder. IGS is inherited in an autosomal recessive manner
• The disorder is caused by a mutation in either the AMN or CUBN genes, which code for amnionless or cubilin proteins, respectively. The proteins are components of vitamin B12-intrinsic factor complex in the intestinal cells, known as enterocytes, as well as the receptor complex for protein reabsorption from urine
• When either amnionless or cubilin protein is aberrant in the complex, the B12 vitamin in the intestines and the protein absorption from primary urine are both dysfunctional. This leads to the symptoms of Imerslund-Gräsbeck Syndrome
• Since vitamin B12 cannot be made by the body and can only be procured from food, its inefficient absorption leads to symptoms including megaloblastic anemia, neurological issues including numbness and tingling sensations in hands and feet, confusion, low muscle tone, and a delay in achieving developmental milestones
• About 50% of the affected individuals have proteinuria, which is the presence of protein in urine. If Imerslund-Gräsbeck Syndrome is left untreated, it can lead to brain damage and the neurological symptoms may become permanent
• Intramuscular injection of cobalamin is the treatment method for combating the condition. Tests are again conducted after beginning the injections to ensure that the deficiency has been corrected. However, the injections have to be continued lifelong in order for an affected individual to lead a normal life
• Since Imerslund-Gräsbeck Syndrome has a genetic basis, there are currently no methods or guidelines available for preventing the disorder. Prospective parents with a family history of the disorder may benefit from getting genetically tested and seeking genetic counselling
• With sustained treatment, the prognosis of Imerslund-Gräsbeck Syndrome is excellent. However, proteinuria continues to be present in the affected individuals; but, it does not worsen and there is no kidney damage reported

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