Mutations in the Alpha 1,2-Mannosidase Gene Essay -- Scientific Resear

Introduction Intellectual disability (ID) is defined by the American Association of Intellectual Developmental Disabilities as having â€Å"significant limitations both in intellectual functioning and in adaptive behavior†. [1] Earlier it was believed that behavioral abnormalities, such as Intellectual Disability, were caused by the social or environmental environment in which the individual lived in.[2] However, with the breakthrough of the genetic analysis, it has been shown that more and more of our behavior is influenced, if not controlled, by our genes. [3]This advancement is important for our understanding of ID to expand. ID can occur when there is a mutation on one or more of the genes in the individual’s chromosome set. [3]There are different types of mutations; autosomal mutations (mutations occurring in one or more of the 44 autosomal chromosomes [in humans]), mutations in the sex chromosomes (the two chromosomes that amongst other things determine the individual’s sex), and there are also chromosomal disorders such as nondisjunction in where one of the two homologous chromosomes fails to separate from its sister chromatid during cell division, resulting in an extra chromosome in one daughter cell and one less chromosome in the other. [3] For parents that are carriers (heterozygous) of an allele that codes for an autosomal recessive trait (e.g. ID), each child they have will inherit one of the two alleles (dominant or recessive) from each parent. Following the Mendelian laws of inheritance, such parents can get offspring that are homozygous dominant (25% chance, will not result in ID), heterozygous like themselves (50% chance, will not result in ID, but will be carriers of the defective gene), or homozygous r... ...tations in the alpha 1,2-mannosidase gene, MAN1B1, cause autosomal-recessive intellectual disability. Am J Hum Genet. 2011 Jul 15;89(1):176-82. [6] Exome Sequencing [Internet]. Mountain View CA: Centrillion, 2011 [cited 2012 Feb 18]. Available from: http://www.centrillionbio.com/exome.php [7] Sanger F, Nicklen S, Coulson AR. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 December; 74(12): 5463–5467. [8] MeSH Browser [Internet]. Stockholm: Karolinska Institutet Universitetsbiblioteket; 2008 [updated 2011; cited 2012 Feb 20]. Available from: http://mesh.kib.ki.se/swemesh/swemesh_se.cfm. Leonard H, Wen X. The epidemiology of mental retardation: Challenges and opportunities in the new millenium. Ment. Retard. Dev. Disabil. Res. Rev., 8 (2002), pp. 117–134. Corresponding author: Helen Leonard (hleonard@cyllene.uwa.edu Mutations in the Alpha 1,2-Mannosidase Gene Essay -- Scientific Resear Introduction Intellectual disability (ID) is defined by the American Association of Intellectual Developmental Disabilities as having â€Å"significant limitations both in intellectual functioning and in adaptive behavior†. [1] Earlier it was believed that behavioral abnormalities, such as Intellectual Disability, were caused by the social or environmental environment in which the individual lived in.[2] However, with the breakthrough of the genetic analysis, it has been shown that more and more of our behavior is influenced, if not controlled, by our genes. [3]This advancement is important for our understanding of ID to expand. ID can occur when there is a mutation on one or more of the genes in the individual’s chromosome set. [3]There are different types of mutations; autosomal mutations (mutations occurring in one or more of the 44 autosomal chromosomes [in humans]), mutations in the sex chromosomes (the two chromosomes that amongst other things determine the individual’s sex), and there are also chromosomal disorders such as nondisjunction in where one of the two homologous chromosomes fails to separate from its sister chromatid during cell division, resulting in an extra chromosome in one daughter cell and one less chromosome in the other. [3] For parents that are carriers (heterozygous) of an allele that codes for an autosomal recessive trait (e.g. ID), each child they have will inherit one of the two alleles (dominant or recessive) from each parent. Following the Mendelian laws of inheritance, such parents can get offspring that are homozygous dominant (25% chance, will not result in ID), heterozygous like themselves (50% chance, will not result in ID, but will be carriers of the defective gene), or homozygous r... ...tations in the alpha 1,2-mannosidase gene, MAN1B1, cause autosomal-recessive intellectual disability. Am J Hum Genet. 2011 Jul 15;89(1):176-82. [6] Exome Sequencing [Internet]. Mountain View CA: Centrillion, 2011 [cited 2012 Feb 18]. Available from: http://www.centrillionbio.com/exome.php [7] Sanger F, Nicklen S, Coulson AR. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 December; 74(12): 5463–5467. [8] MeSH Browser [Internet]. Stockholm: Karolinska Institutet Universitetsbiblioteket; 2008 [updated 2011; cited 2012 Feb 20]. Available from: http://mesh.kib.ki.se/swemesh/swemesh_se.cfm. Leonard H, Wen X. The epidemiology of mental retardation: Challenges and opportunities in the new millenium. Ment. Retard. Dev. Disabil. Res. Rev., 8 (2002), pp. 117–134. Corresponding author: Helen Leonard (hleonard@cyllene.uwa.edu