Question 1

Gene silencing has been effective in mouse models of HD that are heterozygous for the mHTT gene.The results are promising as_______ .

Accepted Answer

The study demonstrated that the gene silencing technique specifically targeted only the mHTT allele, leaving the normal HTT expression level unchanged.

Question 2

Other neurodegenerative diseases also function through aggregation of misfolded proteins.However,the initial protein aggregates are different in each disease.Work on HD may still be vital to treating other diseases as_______
.
A)not all neurodegenerative disease spread
B)the method of disaggregation is similar in all neurodegenerative disease
C)other neurodegenerative diseases use axonal transport to spread to unaffected cells
D)the method of aggregation is the same in all neurodegenerative disease

Accepted Answer

C

Question 3

Explain how the use of sequencing technologies finally brought the search for the HD gene to a close as reported by the Huntington's Disease Collaborative Research Group.

Accepted Answer

Sequencing of the contigs that covered the end of Chromosome 4 that had been previously identified as the location of the HD locus revealed an "interesting contig" that contained a CAG repeat sequence.The population of individuals without HD had 17 alleles with CAG repeats varying from 11 to 34 copies.HD individuals had alleles with 42-66 repeats of the CAG trinucleotide.HD was known to be a trinucleotide repeat disease and the research group proposed HTT as the gene responsible for HD and named its gene product huntingtin.

Question 4

Neurogenetics is_______ .

Accepted Answer

The answer of Neurogenetics is_______ .
...

Question 5

Why does the mHTT gene have such wide- ranging effects in the disease state?

Accepted Answer

The answer of Why does the mHTT gene have such...

Question 6

Researcher Xiao- Jiang Li has used _______to edit the exon of hua mutant HTT allele in mice.Three weeks after the injection of therapeutic into the brain the mice demonstrated a reduction in protein aggregates.

Accepted Answer

CRISPR-Cas is a gene editing tool that can be used to edit specific genes. In this case, the researcher used it to edit the exon of the mutant HTT gene in mice. The therapeutic was injected into the brain after the editing was done, and it led to a reduction in protein aggregates in the mice. The other options, lentiviral transfection, TALENs, and ZFNs, are also gene editing tools, but they are not as efficient and precise as CRISPR-Cas.

Question 7

Huntington's observations of the disease that later took his name were published prior to the rediscovery of Gregor Mendel's work on inheritance.Support the argument that Huntington was describing a phenotype with complete dominance.

Accepted Answer

The answer of Huntington's observations of the disease that later...

Question 8

HD heredity seems to increase if a father inherits the mutant allele from his mother.This is most likely caused by_______ .

Accepted Answer

Imprinting refers to the process where certain genes are preferentially expressed from either the maternal or paternal copy of a gene. In the case of HD, if a father inherits the mutant allele from his mother, it is possible that the expression of that allele is influenced by imprinting, leading to an increased risk of passing on the disease to his own children. This is supported by studies that have identified differential gene expression patterns in individuals with HD based on the parent of origin for the mutant allele.

Question 9

An important study of HD conducted by A.Yamamoto demonstrated that turning off the HTT gene early in the progression of the disease results in the aggregates being degraded and prevention of the disease.Explain how Yamamoto designed his experiment.

Accepted Answer

The answer of An important study of HD conducted by...

Question 10

The second study by Gusella demonstrated four haplotypes for HD based on the restriction enzyme HindIII. Which haplotype demonstrated linkage to the disease phenotype?

Accepted Answer

Haplotype C demonstrated linkage to the Huntington's disease phenotype in Gusella's study using the restriction enzyme HindIII.

Question 11

The success of Gusella,Wexler,and their colleagues in mapping both the G8 marker and HD gene to chromosome 4 launched a new branch of genetics called_______ .

Accepted Answer

The answer of The success of Gusella,Wexler,and their colleagues in...

Question 12

How do Parkinson's causing aggregates enter unaffected cells?

Accepted Answer

Alpha-synuclein aggregates can enter unaffected cells through endocytosis, a process where the cell membrane invaginates and engulfs the aggregates, forming an endosome inside the cell. Once inside the cell, the aggregates can cause harm by interfering with normal cellular processes.

Question 13

HD was the first example of complete dominance in human inheritance.Describe the impact this has on inheriting the disease state.

Accepted Answer

The answer of HD was the first example of complete...

Question 14

The favored model organism for studying the development of HD is_______ .

Accepted Answer

Mice are the favored model organism for studying the development of HD due to their similar neurological and behavioral characteristics to humans, as well as the ability to genetically manipulate and study their nervous systems. Option A (H. sapiens) is not a model organism but the actual species affected by HD. Options C (C. elegans) and D (D. melanogaster) are commonly used for genetic studies but are not suitable for studying HD as they do not have a complex nervous system like mice and humans do.

Question 15

HD is known as a polyQ disease.How does "polyQ" relate to HD?

Accepted Answer

PolyQ refers to a repeating sequence of the amino acid glutamine (abbreviated as Q) in the huntingtin protein. In HD, there is an abnormal expansion of CAG trinucleotide repeats in the HTT gene, which results in the production of a huntingtin protein with an abnormally long polyQ tract. This polyQ expansion is thought to contribute to the toxicity of the mutant huntingtin protein and the pathology of HD.

Question 16

How does the development of protein aggregates in Huntington's disease bring about dementia in patients?

Accepted Answer

In Huntington's disease, protein aggregates develop in the caudate region of the brain, which is responsible for motor control and cognitive processing. As the protein aggregates accumulate, they disrupt the neuronal connection between the caudate region and the frontal lobe, which results in the development of dementia in patients. The disruption of this connection leads to progressive cognitive decline, including memory loss, difficulty in processing information, and inability to plan and organize.

Question 17

Early mapping of the HD gene was done using _______.

Accepted Answer

RFLP mapping, or Restriction Fragment Length Polymorphism mapping, was a commonly used technique in the 1990s to map the location of genes on chromosomes. It involves cutting DNA samples with restriction enzymes and then sorting the resulting fragments by size using gel electrophoresis. The size differences can reveal differences between individuals or strains, allowing for the discovery of polymorphisms that can be used to map disease genes. RFLP mapping was one of the early techniques used to map the location of the HD gene on chromosome 4.

Question 18

Since the discovery of the HTT gene,genetic testing for the number of CAG repeats has been developed.However,there are serious ethical questions raised by the prospect of prenatal testing as well as the testing of minors.Develop an argument for why minors should not be tested for HD unless they demonstrate juvenile HD symptoms.

Accepted Answer

The answer of Since the discovery of the HTT gene,genetic...

Question 19

Huntington's disease HD)is the model neurodegenerative disease because_______ .

Accepted Answer

Huntington's disease is monogenic, meaning it is caused by a mutation in a single gene. This makes it easier to study and understand compared to other neurodegenerative diseases that may be caused by multiple genetic and environmental factors.

Quiz 32: Advances in Neurogenetics: The Study of Huntington Disease