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    ABCC8 Gene

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    Submitted by: Bruce Ren
    (This entry belongs to Entry Collection "MedlinePlus ")

    Definition

    ATP binding cassette subfamily C member 8

    1. Normal Function

    The ABCC8 gene provides instructions for making the sulfonylurea receptor 1 (SUR1) protein. The SUR1 protein is one part (subunit) of the ATP-sensitive potassium (K-ATP) channel that is found across cell membranes in the beta cells of the pancreas. Beta cells secrete insulin, which is a hormone that helps control blood sugar levels. Insulin controls how much sugar (in the form of glucose) is passed from the bloodstream into cells to be used as energy. The K-ATP channel controls the secretion of insulin out of beta cells and into the bloodstream. These channels open and close in response to the amount of glucose in the bloodstream, which helps regulate insulin secretion and control blood sugar levels. The closing of the channels results in a process that triggers insulin secretion by beta cells.

    2. Health Conditions Related to Genetic Changes

    2.1 Congenital hyperinsulinism

    More than 300 mutations in the ABCC8 gene have been found to cause congenital hyperinsulinism. This condition causes frequent episodes of low blood sugar (hypoglycemia), decreased energy, and irritability. Most of these mutations change single protein building blocks (amino acids) in the SUR1 protein.

    Some ABCC8 mutations prevent the SUR1 protein from reaching the cell membrane, interfering with the proper formation of the K-ATP channel. Other mutations interfere with the K-ATP channel's function or its responses to outside molecules. Defective K-ATP channels lead to the constant release of insulin from beta cells. As a result, glucose is rapidly removed from the bloodstream. Without treatment, the hypoglycemia caused by congenital hyperinsulinism may result in serious complications such as intellectual disability and seizures.

    2.2 Permanent neonatal diabetes mellitus

    At least 14 mutations in the ABCC8 gene have been identified in people with permanent neonatal diabetes mellitus. Individuals with this condition often have a low birth weight and develop increased blood sugar (hyperglycemia) within the first 6 months of life.

    ABCC8 gene mutations that cause permanent neonatal diabetes mellitus change single amino acids in the protein sequence. These mutations result in K-ATP channels that do not close, leading to reduced insulin secretion from beta cells and impaired blood sugar control.

    2.3 Maturity-onset diabetes of the young

    MedlinePlus Genetics provides information about Maturity-onset diabetes of the young

    2.4 Other disorders

    Other ABCC8 gene mutations that have a relatively mild effect on K-ATP channel function as compared to that seen in permanent neonatal diabetes mellitus (see above) cause a condition called transient neonatal diabetes mellitus. Infants with this condition have hyperglycemia during the first 6 months of life, but their blood sugar returns to normal by age 18 months. However, affected individuals usually develop hyperglycemia again during adolescence or early adulthood. As in permanent neonatal diabetes mellitus, ABCC8 gene mutations that cause transient neonatal diabetes mellitus interfere with K-ATP channel closure and lead to a reduction in insulin secretion.

    Some studies suggest that normal variations (polymorphisms) in the ABCC8 gene are associated with an increased risk of type 2 diabetes, the most common form of diabetes. Other studies, however, have not found an association between ABCC8 gene variants and type 2 diabetes. People with this disease have hyperglycemia because the body does not respond correctly to the insulin secreted from beta cells. Although changes in the ABCC8 gene may be associated with type 2 diabetes, a combination of lifestyle, genetic, and environmental factors all play a part in determining the risk of this complex disorder.

    3. Other Names for This Gene

    • ABC36
    • ABCC8_HUMAN
    • ATP-binding cassette, sub-family C (CFTR/MRP), member 8
    • ATP-binding cassette, sub-family C, member 8
    • MRP8
    • SUR
    • SUR1
    • TNDM2

    This entry is adapted from https://medlineplus.gov/genetics/gene/abcc8

    References

    1. Bennett K, James C, Hussain K. Pancreatic β-cell KATP channels: Hypoglycaemia and hyperglycaemia. Rev Endocr Metab Disord. 2010 Sep;11(3):157-63. doi:10.1007/s11154-010-9144-2. Review.
    2. Edghill EL, Flanagan SE, Ellard S. Permanent neonatal diabetes due toactivating mutations in ABCC8 and KCNJ11. Rev Endocr Metab Disord. 2010Sep;11(3):193-8. doi: 10.1007/s11154-010-9149-x. Review.
    3. Ellard S, Flanagan SE, Girard CA, Patch AM, Harries LW, Parrish A, Edghill EL,Mackay DJ, Proks P, Shimomura K, Haberland H, Carson DJ, Shield JP, HattersleyAT, Ashcroft FM. Permanent neonatal diabetes caused by dominant, recessive, orcompound heterozygous SUR1 mutations with opposite functional effects. Am J HumGenet. 2007 Aug;81(2):375-82.
    4. Flanagan SE, Clauin S, Bellanné-Chantelot C, de Lonlay P, Harries LW, GloynAL, Ellard S. Update of mutations in the genes encoding the pancreatic beta-cell K(ATP) channel subunits Kir6.2 (KCNJ11) and sulfonylurea receptor 1 (ABCC8) indiabetes mellitus and hyperinsulinism. Hum Mutat. 2009 Feb;30(2):170-80. doi:10.1002/humu.20838. Review.
    5. Flanagan SE, Patch AM, Mackay DJ, Edghill EL, Gloyn AL, Robinson D, Shield JP,Temple K, Ellard S, Hattersley AT. Mutations in ATP-sensitive K+ channel genescause transient neonatal diabetes and permanent diabetes in childhood oradulthood. Diabetes. 2007 Jul;56(7):1930-7.Diabetes. 2008 Feb;57(2):523.
    6. Gloyn AL, Siddiqui J, Ellard S. Mutations in the genes encoding the pancreaticbeta-cell KATP channel subunits Kir6.2 (KCNJ11) and SUR1 (ABCC8) in diabetesmellitus and hyperinsulinism. Hum Mutat. 2006 Mar;27(3):220-31. Review.
    7. Huopio H, Shyng SL, Otonkoski T, Nichols CG. K(ATP) channels and insulinsecretion disorders. Am J Physiol Endocrinol Metab. 2002 Aug;283(2):E207-16.Review.
    8. Pinney SE, MacMullen C, Becker S, Lin YW, Hanna C, Thornton P, Ganguly A,Shyng SL, Stanley CA. Clinical characteristics and biochemical mechanisms ofcongenital hyperinsulinism associated with dominant KATP channel mutations. JClin Invest. 2008 Aug;118(8):2877-86. doi: 10.1172/JCI35414.
    9. Sandal T, Laborie LB, Brusgaard K, Eide SA, Christesen HB, Søvik O, NjølstadPR, Molven A. The spectrum of ABCC8 mutations in Norwegian patients withcongenital hyperinsulinism of infancy. Clin Genet. 2009 May;75(5):440-8.
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