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This question is based on: Human Molecular Genetics, 1997, Vol. 6, No. 5 The image below
shows a pedigree for a family with a de novo mutation in the huntingtin gene (HTT gene)(the gene
mutated in Huntington's Disase):
pedigree As the figure legend indicates, each individual with an asterisk below was sequenced for
the HTT gene and the number of CAG repeats determined. See the table below. table of repeat
sizes
1. Which of the following could be the repeat size genotypes of the parents of individuals labeled
with 1, 2, 3, 7, and 8?
Select all that apply.
Group of answer choices
18 repeats and 17 repeats
37 repeats and 15 repeats
15 repeats and 17 repeats
37 repeats and 18 repeats
2. The individual marked by the arrow (the proband) died of Huntington's disease at the age of 45.
Which of the following statements could be true about this individual?
Select all that apply.
Group of answer choices
The individual has more than 37 repeats in the HTT gene because during gamete formation in his
parent the new strand slipped backward during DNA replication.
The individual has more than 37 repeats in the HTT gene because during gamete formation in his
parent the template strand slipped backward during DNA replication.
The individual has 38 repeats in the HTT gene and the disease is penetrant.
The individual has two disease alleles for the HTT gene.
Figure 1. Family #2 represents a large family with de novo HD containing many individuals who
survived to old age without neurological impairment among the ancestors of the individual with the
fresh mutation (arrow). Age at death is listed below deceased individuals and current age for those
living. Individuals from whom blood samples were obtained are indicated by an asterisk. Numbers
cited in Table 1 are presented below the asterisk. The pedigree has been modified to conceal the
identities of those studied.Table 1. Family 2

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This question is based on Human Molecular Genetics 1997 V.pdf

  • 1. This question is based on: Human Molecular Genetics, 1997, Vol. 6, No. 5 The image below shows a pedigree for a family with a de novo mutation in the huntingtin gene (HTT gene)(the gene mutated in Huntington's Disase): pedigree As the figure legend indicates, each individual with an asterisk below was sequenced for the HTT gene and the number of CAG repeats determined. See the table below. table of repeat sizes 1. Which of the following could be the repeat size genotypes of the parents of individuals labeled with 1, 2, 3, 7, and 8? Select all that apply. Group of answer choices 18 repeats and 17 repeats 37 repeats and 15 repeats 15 repeats and 17 repeats 37 repeats and 18 repeats 2. The individual marked by the arrow (the proband) died of Huntington's disease at the age of 45. Which of the following statements could be true about this individual? Select all that apply. Group of answer choices The individual has more than 37 repeats in the HTT gene because during gamete formation in his parent the new strand slipped backward during DNA replication. The individual has more than 37 repeats in the HTT gene because during gamete formation in his parent the template strand slipped backward during DNA replication. The individual has 38 repeats in the HTT gene and the disease is penetrant. The individual has two disease alleles for the HTT gene. Figure 1. Family #2 represents a large family with de novo HD containing many individuals who survived to old age without neurological impairment among the ancestors of the individual with the fresh mutation (arrow). Age at death is listed below deceased individuals and current age for those living. Individuals from whom blood samples were obtained are indicated by an asterisk. Numbers cited in Table 1 are presented below the asterisk. The pedigree has been modified to conceal the identities of those studied.Table 1. Family 2