BIOL239 Lecture Notes - Chromosomal Translocation, Primary Transcript, Intellectual Disability
Document Summary
Set 20: chromosomal rearrangements, all are mutations . An heritable change in dna sequence: deletions. Homozygosity for gene deletions is often, but not always, lethal. Gene dosage the number of times a given gene is present in the genome: gene-dosage effect. A deletion of an entire gene(s) or even a segment of the gene results in a single dose of that gene product in an otherwise diploid individual (which normally relies on two doses) Deletion on the short arm of c5 (chromosome five) Heterozygotes have a small head, wide-spaced eyes, round face and cognitive deficiencies: crit-du-chat syndrome. Note the deletion of short arm for chromosome 5. Cri-du-chat cry of a cat in french. It is called this because these things usually make infants cry: heterozygosity for deletions may have phenotypic consequences, duplications. Duplications increase the copy number of a particular chromosomal region. Tandem duplications lie adjacent to each other, either in the same order or in reverse order.