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The official name of this gene is “amnion associated transmembrane protein.”
AMN is the gene's official symbol. The AMN gene is also known by other names, listed below.
The AMN gene provides instructions for making a protein called amnionless. This protein is involved in the uptake of vitamin B12 (also called cobalamin) from food. Vitamin B12, which cannot be made in the body and can only be obtained from food, is essential for the formation of DNA and proteins, the production of cellular energy, and the breakdown of fats. This vitamin is involved in the formation of red blood cells and maintenance of the brain and spinal cord (central nervous system).
The amnionless protein is primarily found embedded in the outer membrane of kidney cells and cells that line the small intestine. Amnionless attaches (binds) to another protein called cubilin, anchoring cubilin to the cell membrane. Cubilin can interact with molecules and proteins passing through the intestine or kidneys. During digestion, vitamin B12 is released from food. As the vitamin passes through the small intestine, cubilin binds to it. Amnionless helps transfer the cubilin-vitamin B12 complex into the intestinal cell. From there, the vitamin is released into the blood and transported throughout the body. In the kidneys, amnionless and cubilin are involved in the reabsorption of certain proteins that would otherwise be released in urine.
At least 30 mutations in the AMN gene have been found to cause Imerslund-Gräsbeck syndrome. This condition is characterized by low levels of vitamin B12 in the body, which leads to a blood disorder known as megaloblastic anemia. About half of affected individuals also have excess protein in their urine (proteinuria), and some have neurological problems.
AMN gene mutations that cause Imerslund-Gräsbeck syndrome reduce the amount or function of the amnionless protein. Without amnionless acting as an anchor, cubilin is not attached to cells in the small intestine or kidneys and cannot bind to vitamin B12 and other molecules and proteins needed in the body. As a result, instead of being taken into intestinal cells, vitamin B12 is released from the body. A shortage of this essential vitamin impairs the proper development of red blood cells, leading to megaloblastic anemia. Low levels of vitamin B12 can also affect the central nervous system, causing neurological problems. In addition, without amnionless function in the kidneys, proteins are not reabsorbed into the body and are instead released in the urine, leading to proteinuria.
Cytogenetic Location: 14q32.3
Molecular Location on chromosome 14: base pairs 102,922,547 to 102,930,846
The AMN gene is located on the long (q) arm of chromosome 14 at position 32.3.
More precisely, the AMN gene is located from base pair 102,922,547 to base pair 102,930,846 on chromosome 14.
See How do geneticists indicate the location of a gene? (http://ghr.nlm.nih.gov/handbook/howgeneswork/genelocation) in the Handbook.
You and your healthcare professional may find the following resources about AMN helpful.
You may also be interested in these resources, which are designed for genetics professionals and researchers.
See How are genetic conditions and genes named? (http://ghr.nlm.nih.gov/handbook/mutationsanddisorders/naming) in the Handbook.
anemia ; breakdown ; cell ; cell membrane ; central nervous system ; cobalamin ; digestion ; DNA ; endocytosis ; gene ; intestine ; kidney ; megaloblastic anemia ; nervous system ; neurological ; precursor ; protein ; proteinuria ; syndrome ; transmembrane ; vitamin B12
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (/glossary).
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? (http://ghr.nlm.nih.gov/handbook/consult/findingprofessional) in the Handbook.