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The smallest single base deletion mutations occur by a single base flipping in the template DNA, followed by template DNA strand slippage, within the DNA polymerase active site. [3] [4] [5] Deletions can be caused by errors in chromosomal crossover during meiosis, which causes several serious genetic diseases.
The following is a list of genetic disorders and if known, type of mutation and for the chromosome involved. Although the parlance "disease-causing gene" is common, it is the occurrence of an abnormality in the parents that causes the impairment to develop within the child.
Pearson syndrome is a mitochondrial disease caused by a deletion in mitochondrial DNA (mtDNA). [3] An mtDNA is genetic material contained in the cellular organelle called the mitochondria. Depending on the tissue type, each cell contains hundreds to thousands of mitochondria. There are 2–10 mtDNA molecules in each mitochondrion.
The three major single-chromosome mutations: deletion (1), duplication (2) and inversion (3). The two major two-chromosome mutations: insertion (1) and translocation (2). When the chromosome's structure is altered, this can take several forms: [16] Deletions: A portion of the chromosome is missing or has been deleted.
A newer theory suggests that the selective pressure on the CCR5 Delta 32 mutation was caused by smallpox instead of the bubonic plague. [117] Malaria resistance: An example of a harmful mutation is sickle-cell disease, a blood disorder in which the body produces an abnormal type of the oxygen-carrying substance haemoglobin in the red blood cells.
Prader–Willi (PWS) and Angelman syndrome (AS) are distinct neurogenetic disorders caused by chromosomal deletions, uniparental disomy or loss of the imprinted gene expression in the 15q11-q13 region. Whether an individual exhibits PWS or AS depends on if there is a lack of the paternally expressed gene to contribute to the region.
A single point mutation in this polypeptide chain, which is 147 amino acids long, results in the disease known as Sickle Cell Anemia. [18] Sickle-cell anemia is an autosomal recessive disorder that affects 1 in 500 African Americans, and is one of the most common blood disorders in the United States. [ 17 ]
13q deletion syndrome is a rare genetic disease caused by the deletion of some or all of the large arm of human chromosome 13. Depending upon the size and location of the deletion on chromosome 13, the physical and mental manifestations will vary. It has the potential to cause intellectual disability and congenital malformations that affect a ...