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The official name of this gene is “microsomal triglyceride transfer protein.”
MTTP is the gene's official symbol. The MTTP gene is also known by other names, listed below.
The MTTP gene provides instructions for making a protein called microsomal triglyceride transfer protein. The microsomal triglyceride transfer protein helps produce beta-lipoproteins, which are molecules that consist of proteins combined with cholesterol and particular types of fats called phospholipids and triglycerides. These beta-lipoproteins contain the protein apolipoprotein B, which is critical for the creation of molecules called chylomicrons. Chylomicrons are formed when dietary fats and cholesterol are absorbed from the intestines. Chylomicrons are also necessary for the absorption of certain fat-soluble vitamins, especially vitamins E, A, and sometimes K.
Other beta-lipoproteins containing apolipoprotein B, particularly low-density lipoproteins (LDL) and very low-density lipoproteins (VLDL), are created by microsomal triglyceride transfer protein in the liver. These lipoproteins transport fats, cholesterol, and fat-soluble vitamins throughout the body in the bloodstream. Sufficient levels of fats, cholesterol, and vitamins are necessary for normal growth, development, and maintenance of the body's cells and tissues, particularly nerve cells and tissues in the eye.
More than 30 mutations that cause abetalipoproteinemia have been identified in the MTTP gene. One particular mutation is more common in people of Ashkenazi (eastern and central European) Jewish descent; this mutation replaces the protein building block (amino acid) glycine with a stop signal at position 865 (written as Gly865X or G865X). As a result of this amino acid change, an abnormally small, nonfunctional version of the protein is made. Similarly, many other mutations that cause abetalipoproteinemia produce abnormally short microsomal triglyceride transfer proteins. A shortened protein is unable to produce beta-lipoproteins, resulting in a severe deficiency of chylomicrons, low-density lipoproteins, and very low-density lipoproteins. The absence of these lipoproteins prevents dietary fats and fat-soluble vitamins from being absorbed and carried to the rest of the body, leading to the nutritional and neurological problems seen in people with abetalipoproteinemia.
Cytogenetic Location: 4q24
Molecular Location on chromosome 4: base pairs 99,564,082 to 99,623,996
The MTTP gene is located on the long (q) arm of chromosome 4 at position 24.
More precisely, the MTTP gene is located from base pair 99,564,082 to base pair 99,623,996 on chromosome 4.
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 MTTP 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.
amino acid ; apolipoprotein ; beta-lipoproteins ; carrier ; cholesterol ; chylomicrons ; deficiency ; gene ; glycine ; LDL ; low-density lipoproteins ; mutation ; neurological ; protein ; soluble ; subunit ; triglycerides ; vitamins ; VLDL
You may find definitions for these and many other terms in the Genetics Home Reference Glossary (http://www.ghr.nlm.nih.gov/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.