Concept explainers
Roberts syndrome is a rare inherited disorder characterized by facial defects as well as severe limb shortening, extra digits, and deformities of the knees and ankles. A cytogenetic analysis of patients with Roberts syndrome, using Giemsa staining or C-banding, reveals that there is premature separation of centromeres and other heterochromatic regions during mitotic metaphase instead of anaphase. A couple with an affected infant is contacted by a local organization dedicated to promoting research on rare genetic diseases, asking if they can photograph the infant as part of a campaign to obtain funding for these conditions. The couple learned that the privacy of such medical images is not well protected, and they often are subsequently displayed on public websites. The couple was torn between helping to raise awareness and promoting research on this condition and sheltering their child from having his images used inappropriately. Several interesting questions are raised.
If the parents decide to allow their infant to be photographed, what steps should the local organization take to ensure appropriate use and distribution of the photos?
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Concepts of Genetics (12th Edition)
- Variations in Chromosome NumberAneuploidy Describe the process of nondisjunction and explain when it takes place during cell division.arrow_forwardFamilial retinoblastoma, a rare autosomal dominant defect, arose in a large family that had no prior history of the disease. Consider the following pedigree (the darkly colored symbols represent affected individuals): a. Circle the individual(s) in which the mutation most likely occurred. b. Is the person who is the source of the mutation affected by retinoblastoma? Justify your answer. c. Assuming that the mutant allele is fully penetrant, what is the chance that an affected individual will have an affected child?arrow_forwardA colleague e-mails you saying that she has identified an interesting chromosome variation at 21q13. In discussing this discovery with a friend who is not a cytogeneticist, explain how you would describe this location, defining each term in the chromosome address 21q13.arrow_forward
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- Given the end results of the two types of cell division, why is it necessary for homologs to pair during meiosis and not desirable for them to pair during mitosis?arrow_forwardWhy is a chromosomal fragment without a centromeresubsequently lost and degraded?arrow_forwardIn humans, chromosome 16 sometimes has a heavily stained area in the long arm near the centromere. This feature can be seen through the microscope but has no effect on the phenotype of the person carrying it. When such a “blob” exists on a particular copy of chromosome 16, it is a constant feature of that chromosome and is inherited. A couple conceived a child, but the fetus had multiple abnormalities and was miscarried. When the chromosomes of the fetus were studied, it was discovered that it had three copies of chromosome 16 (it was trisomic for chromosome 16), and that two of the three chromosome 16s had large blobs. Both chromosome 16 homologs in the mother lacked blobs, but the father was heterozygous for blobs. Which parent experienced nondisjunction, and in which meiotic division did it occur?arrow_forward
- In Figure 12-11b, in what chromosomal region are youlikely to find the most H1 histone protein?arrow_forwardA son and his mother both have an inherited disorder that affects the nervous system. How would you determine if the disorder is caused by a change inchromosome structure, such as a deletion or duplication?arrow_forwardwhy The chromatids formed byrecombination within the inversion loop of a pericentric inversionheterozygote are genetically unbalanced?arrow_forward
- Human Heredity: Principles and Issues (MindTap Co...BiologyISBN:9781305251052Author:Michael CummingsPublisher:Cengage Learning