Are exons duplicated?
Tandem exon duplication is defined as duplication of exons within the same gene to give rise to the subsequent exon. A complete exon analysis of all genes in Homo sapiens, Drosophila melanogaster, and Caenorhabditis elegans has shown 12,291 instances of tandem duplication in exons in human, fly, and worm.
How many exons are in a DMD gene?
The dystrophin gene (DMD), with its 79 constitutive exons, and at least other 7 alternatively-used exons, is the largest known human gene, spanning 2.2 Mb of genomic DNA (Muntoni et al., 2003).
What is the cause of duplication?
Duplications arise from an event termed unequal crossing-over that occurs during meiosis between misaligned homologous chromosomes. The chance of it happening is a function of the degree of sharing of repetitive elements between two chromosomes.
What is an exon mutation?
Deletions occur when pieces of the gene (called exons) are missing. Deletions of one or more exons are the most common type of mutation. Since there are a total of 79 exons in the dystrophin gene, there are many different deletions that can occur.
How many types of duplication are there?
Gene duplication can occur by several mechanisms, including whole-genome duplication (WGD) and single gene duplication. Single gene duplication includes four types, tandem (TD), proximal (PD), retrotransposed (RD), DNA-transposed (DD) and dispersed duplication (DSD) (Freeling, 2009; Hahn, 2009; Wang et al., 2012b).
Which exons are mutated in DMD?
As mentioned earlier, DMD is caused by mutations in the DMD gene, mostly the deletion of one or more of the 79 exons in the dystrophin gene. These mutations disturb the synthesis of the dystrophin protein.
What is exon skipping drug?
Exon skipping uses small drugs called antisense oligonucleotides to help cells skip over a specific exon during splicing. This allows cells to join a different set of exons together to produce a protein that is shorter than usual but may have some function.