• Emigration (when new organisms join a population, bringing new alleles or changing frequencies) or immigration (when new organisms join a population, bringing new alleles or changing frequencies) can both cause changes in the population's relative allele frequencies (when members of a population leave it, taking with them their genes). (ignouhelpcenter.com)
  • As a result, one of the variables that causes changes in allele frequencies in a population is migration. (ignouhelpcenter.com)
  • Random changes in allele frequencies in a population caused by chance events are known as genetic drift. (ignouhelpcenter.com)
  • In layman's terms, genetic polymorphism is the presence in the same population of two or more alleles at the same locus, where the frequency of the rarer allele is always more than one percent and the rarer allele is maintained in the population, not just by recurrent mutations. (ignouhelpcenter.com)
  • A different form of a gene at a particular locus. (ojp.gov)
  • In CSR, to diversify the effector function of specific antibodies, recombination occurs within the downstream portion of the IgH locus to join variable region genes with different constant (C H ) region genes ( 4 ). (silverchair.com)
  • In SM, which is the dominant means of secondary alteration of variable region gene sequences in humans and mice, mutations are introduced in the Ig variable region genes at a tremendous rate, which allows for evolution of high affinity antibodies ( 2 ). (silverchair.com)
  • ICF always involves limited hypomethylation of DNA and often arises from mutations in one of the DNA methyltransferase genes ( DNMT3B ). (biomedcentral.com)
  • However, given the variety of DNMT3B mutations, a first-degree affected relative should first have both alleles of this gene sequenced. (biomedcentral.com)
  • The movement of alleles from one group to another through migration is known as gene flow. (ignouhelpcenter.com)
  • To be more precise, genetic drift occurs as a result of 'sampling error' in picking alleles for the future generation from the present generation's gene pool. (ignouhelpcenter.com)
  • Recombination creates new combinations of alleles, increasing genetic diversity in this way. (ignouhelpcenter.com)
  • To diversify the coding potential of the Ig genes, B cells undergo several processes of regulated genetic alterations. (silverchair.com)
  • Later in B cell development, usually after antigen-dependent activation of B cells, the genetic alteration processes of somatic mutation (SM), class switch recombination (CSR), and gene conversion further diversify the antigen-recognition repertoire as well as the effector function of encoded antibodies. (silverchair.com)
  • Early in their development, B cells in the bone marrow undergo V(D)J recombination to juxtapose variable region V, D, and J segments in different combinations, creating a large repertoire of antibodies ( 1 ). (silverchair.com)
  • To investigate the effects of loss of β1 function in vivo , we have used gene-targeting methods to produce β1(-/-) mice, and we have analyzed their neuronal phenotypes. (jneurosci.org)
  • In some vertebrates, such as chickens and pigs, diversification of assembled Ig variable regions occurs by a gene conversion mechanism rather than SM ( 3 ). (silverchair.com)
  • Serum levels of IgG, IgM, IgE, and/or IgA are low, although the type of immunoglobulin deficiency is variable. (biomedcentral.com)
  • The characteristics of a single copy of a specific gene, or of a single copy of a specific location on a chromosome. (ojp.gov)
  • The immune system has evolved specific mechanisms to combat a potentially limitless number of foreign pathogens using a limited arsenal of Ig genes. (silverchair.com)
  • F ST supports its relatedness to breeds from the same geographic origin and provides information on potential gene pools that could be used to maintain diversity in DSN. (frontiersin.org)
  • A gene present on the X and Y sex chromosomes that is used in DNA identification testing to determine the gender of the donor of the DNA in a biological sample. (ojp.gov)
  • Somatic hypermutation (SHM) and class switch recombination (CSR) cause distinct genetic alterations at different regions of immunoglobulin genes in B lymphocytes: point mutations in variable regions and large deletions in S regions, respectively. (silverchair.com)
  • V(D)J recombination, somatic hypermutation (SHM), and class switch recombination (CSR). (silverchair.com)
  • V(D)J recombination takes place in developing B lymphocyte precursors and its biochemical mechanism is well characterized ( 1 ). (silverchair.com)
  • Belonging to the immunoglobulin (Ig) superfamily, antibodies are large, Y-shaped glycoproteins produced by plasma cells. (ukdiss.com)
  • On the other hand, in CSR, two switch (S) regions located 5′ to heavy-chain constant (C H ) region genes are cleaved and a large DNA fragment between the cleavages is excised out from the chromosome to bring in a downstream Ig C H region gene to the proximity of a rearranged V gene ( 7 ). (silverchair.com)