Reference no: EM133415734

Gene Mutations

Here is a Muscular Dystrophy website that discusses some Types of Mutations, including missense mutations (like sickle cell anemia), nonsense mutations (creating a premature stop codon), and insertions, deletions or duplications (also known as repeats). Also, there is a nice website on a lesser-known genetic defect called Rett Syndrome, The Genetics Behind Rett Syndrome (reverserett.org), which does a good job of explaining the naming of many mutations by their DNA base changes and/or their amino acid changes.

The image focuses on the exact location of the most common mutation in CF patients, which is named the ΔF508 mutation (LibreTexts, 2022). The image compares the DNA coding strand sequence in the normal allele for codons 506 through 510 (along with the resulting amino acids that would normally be translated) with the DNA coding sequence at the same location in the ΔF508 allele (along with its translated amino acids). The ΔF508 mutation has a three-base deletion - the CTT bases (highlighted in red in the image) on the normal allele are missing in the ΔF508 allele. When comparing the resulting change to the primary sequence of the protein, this 3-base deletion results in the protein missing one amino acid, a phenylalanine (which can be abbreviated as phe, or in short-hand, as the letter F) which would have been at position 508 in the protein sequence of the chloride ion channel. The Greek letter delta (Δ) means change. Thus, the name of this allele tells you that the mutation is a change (Δ), actually a loss in this case, of the phenylalanine (F) amino acid at position 508 in the protein sequence. The loss of this one amino acid in CF patients with two copies of this recessive allele results in the Class II mutations that we looked at back in an earlier week's assignment. Think about that: the loss of one critical amino acid out of several hundreds of them in the CFTR protein causes the life-threatening symptoms that characterize the phenotype known as Cystic Fibrosis in humans!

Study the CAG mutation that leads to Huntington's disease. One valuable reference is found here: https://serious-science.org/huntingtons-disease-7618

After reviewing the information that you researched, state the name of genetic defect you studied, and provide information from sources you found in your search on the name of the gene associated with your mutation and the name of the enzyme or protein normally produced by that gene, and some phenotypic information, such as specific symptoms associated with the defective allele of the gene. State which mutation type (missense, nonsense, or triplet repeat) that best fits the mutation you were assigned, and define your mutation type. Also share specific information on exactly how the DNA nucleotide sequence and/or how the amino acid sequence of the mutated allele is different from the normal allele. Cite any references.