II II IV 4) [After M. Zeviani et al., 1990, American Journal of Human Genetics 47:904-914.] [After M. Zeviani et al., 1990, American Journal of Human Genetics 47:904-914.]
In a study of a muscle disorder, several affected families exhibited
vision problems, muscle weakness, and deafness (M. Zeviani et al. 1990.
American Journal of Human Genetics 47:904–914). Analysis of the
mtDNA from affected members of these families revealed that large
numbers of their mtDNA molecules possessed deletions of varying
lengths. Different members of the same family and even different
mitochondria from the same person possessed deletions of different
sizes, so the underlying defect appeared to be a tendency for the mtDNA
of affected persons to have deletions. A pedigree of one of the families
studied is shown below. The researchers concluded that this disorder is
inherited as an autosomal dominant trait, and they mapped the diseasecausing
gene to a position on chromosome 10 in the nucleus.
a. What characteristics of the pedigree rule out inheritance of a trait
encoded by a gene in the mtDNA as the cause of this disorder?
b. Explain how a mutation in a nuclear gene might lead to deletions in
mtDNA.
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[After M. Zeviani et al., 1990, American Journal of Human Genetics 47:904-914.]
[After M. Zeviani et al., 1990, American Journal of Human Genetics
47:904-914.]](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F0671424f-5892-4dc3-9cf9-7e742180376e%2F150a0d14-c1b0-4dab-af7b-b8168a3f9080%2Fa8rfyxym.jpeg&w=3840&q=75)
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