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1 maj 2019 · A deletion mutation can remove a single nucleotide, or entire sequences of nucleotides. Deletions are thought to occur when the enzyme that synthesizes new DNA slips on the template DNA strand, effectively missing a nucleotide. This enzyme, polymerase, must attach the template DNA nucleotides in its active site for DNA replication to occur.
Deletions involve the loss of DNA sequences. Phenotypic effects of deletions depend on the size and location of deleted sequences on the genome. For instance, deletions that span a centromere...
Purine dimers are much less common. UV-induced dimerization usually results in a deletion mutation when the modified strand is copied. Another type of UV-induced photoproduct is the (6-4) lesion in which carbons number 4 and 6 of adjacent pyrimidines become covalently linked (Figure 14.9B).
Very rarely, incorrect bases are incorporated or bases omitted from a DNA strand during synthesis. Such mistakes can lead to spontaneous substitutions, insertions or deletions. For example, strand slippage due to the formation of a loop.
Molecular diagnosis of genetic disorders is noticed as the detection of the pathogenic mutations in DNA and/or RNA samples. It could facilitate fine subclassification, prognosis, and therapy of disorders.
For example, in β-thalassemia, the β-globin gene may be altered by deletions, nonsense mutations, splice junction mutations, frame shifts, formation of fusion genes and single base pair mutations. 4 In cystic fibrosis, the most common mutation involves deletion of 3 nucleotides, which results in the protein not reaching its final destination ...
16 mar 2024 · Objectives: Identify clinical encounters appropriate for genetic molecular testing, distinguishing cases where such testing can contribute to diagnosis, prognosis, or treatment decisions. Evaluate genetic test results accurately, discerning their clinical significance and relevance to patient management.
