Genetics: From Genes to Genomes, 5th edition
5th Edition
ISBN: 9780073525310
Author: Leland H. Hartwell, Michael L. Goldberg, Janice A. Fischer, Leroy Hood, Charles F. Aquadro
Publisher: McGraw-Hill Education
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Chapter 21, Problem 15P
Canavan disease, caused by homozygosity for a recessive, severe neurodegenerative syndrome usually resulting in death by the age of 18 months. The frequency of Canavan disease is particularly high in Jewish populations. In an effort to map the gene causing this condition, researchers looked at 10 SNPs (1–10) spaced at roughly 100 kb distances along chromosome 17 in 5 affected Jewish patients and 4 unaffected control Jewish individuals. In the table below, each row depicts a single haplotype. G, C, A, and T represent the actual
| Case | SNP1 | SNP2 | SNP3 | SNP4 | SNP5 | SNP6 | SNP7 | SNP8 | SNP9 | SNP10 |
| 1 | G | T | G | T | T | T | C | A | G | T |
| 2 | A | T | G | T | T | T | C | A | G | T |
| 3 | G | T | G | T | T | T | C | A | G | C |
| 4 | A | A | G | T | T | T | C | T | C | C |
| 5 | G | A | G | C | C | T | G | A | C | C |
| Control | ||||||||||
| 6 | A | A | G | T | T | T | C | A | G | T |
| 7 | G | T | G | G | C | T | G | A | G | T |
| 8 | A | T | C | T | C | G | C | T | C | C |
| 9 | G | T | C | G | T | G | G | A | C | T |
| a. | Does the disease-causing mutation appear to be in linkage disequilibrium with any of the SNP alleles? If so, which ones? |
| b. | Where is the most likely location for the Canavan disease gene? About how long is the region to which you can ascribe the gene? |
| c. | How many independent mutations of the Canavan gene are suggested by these data? |
| d. | Suppose that individuals 2–9 are Ashkenazic (whose ancestors lived in the Rhine river basin of Germany and France after the Jews were expelled from Judea in 70 A.D.) while individual 1 is Sephardic (a non-Ashkenazic Jew). Would these facts provide any information about the history of the mutations causing Canavan disease? |
| e. | For mapping genes by haplotype association, why is it often helpful to focus on certain subpopulations? Does this strategy have any disadvantages? |
| f. | Human chromosome 17 is an autosome, so each person has two copies of each region along the chromosome. With this in mind, how could the researchers determine any individual haplotype, such as any of those shown in the table? |
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The DNA of every individual in the pedigree shown
below has been sequenced at the causative locus.
All the non-shaded individuals are wild type apart
from III.1. III.1 has been proven to have the
causative mutation for this autosomal dominant
condition, but they exhibit no symptoms. Based on
this small pedigree, what is the level of penetrance
for the condition? Please give your answer as a
WHOLE percentage, give the number only, no
percentage symbol.
Answer: The level of penetrance for the
condition shown in the pedigree below is Blank 1
percent.
1:1
1:2
Il:1
I1:2
I1:3
Il:4
I1:5
I1:6
II:1 I:2 III:3
III:4
III:3 III:6 III:7
III:8
III:9
III:10 III:11 III12 II:13 III:14
IV:1 | IV:2 IV:3 IV:4 IV:5 IV:6 IV:7 IV:8 IV:9 IV:10 IV:11 IV:12 IV:13 IV:14 IV:15 IV:16 IV:17
IV:18 IV:19
V:1 V:2 V:3 V:4 V:5
V:6
V:7
V:8 V:9
V:10
V:11 V:12
An STR on chromosome 5 is very closely linked to a gene involved in a dominant metabolism disorder (one one copy of the mutation causes the disease). There are four different alleles of the STR (Q, B, S, and L), each with different numbers of GATCTCG repeats. The S allele
has 2 repeats, the B allele has 7 repeats, the Q allele has 10 repeats, and the L allele has 5 repeats.
Part 1
Lane 1 of the gel shown below indicates the locations of PCR products corresponding to all four STR alleles when run together in one lane. DNA was loaded into the wells at the top of the gel.
Move the letter of each allele to its correct position at the left of Lane 1 to indicate where each allele runs on the gel.
0000
Gabriel
Andre
Lane 1
O Maria
Andre Maria Juliana
B L
Part 2
Andre and Maria are the parents in this family; all others shown on the gel are children. Daughter Juliana is born with the metabolism disorder, but daughter Camila does not have the disorder. Assuming no recombination between the STR…
Susan’s grandfather was deaf, and passed down a hereditary form of deafness within Susan’s family as shown in Figure Q19–12.A. Is this mutation most likely to be dominant or recessive?B. Is it carried on an autosome or a sex chromosome? Why?C. A complete SNP analysis has been done for all of the 11 grandchildren (4 affected, and 7 unaffected). In comparing these 11 SNP results, how long a haplotype block would you expect to find around the critical gene? How might you detect it?
Chapter 21 Solutions
Genetics: From Genes to Genomes, 5th edition
Ch. 21 - Choose the best matching phrase in the right...Ch. 21 - Prob. 2PCh. 21 - How can each of the following be used in...Ch. 21 - Which of the following statements would be true of...Ch. 21 - Prob. 5PCh. 21 - Prob. 6PCh. 21 - Prob. 7PCh. 21 - Human geneticists have found the Finnish...Ch. 21 - Prob. 9PCh. 21 - Prob. 10P
Ch. 21 - In a certain plant, leaf size is determined by...Ch. 21 - Compare and contrast the use of SNP genotyping: i...Ch. 21 - Prob. 13PCh. 21 - Prob. 14PCh. 21 - Canavan disease, caused by homozygosity for a...Ch. 21 - Prob. 16PCh. 21 - Prob. 17PCh. 21 - Consider the triangle diagram shown in Fig. 21.15....Ch. 21 - Prob. 19PCh. 21 - Prob. 20PCh. 21 - Suppose a GWAS investigation found a particular LD...Ch. 21 - In domesticated dogs, size has a high...Ch. 21 - Prob. 23P
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