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Human Genetics > Lecture 9: Gene Therapy and DTC Genetic Services > Flashcards

Lecture 9: Gene Therapy and DTC Genetic Services Flashcards

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Biology 101 flashcards
1
Q

____: The use of recombinant DNA technology to correct a genetic defect in a mutant cell carrying defective gene with purpose of therapeutic outcome

A

Gene Therapy

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2
Q

True or False: In order to approach a disease for gene therapy potential, it must be a trigenic disease

A

False - must be monogenic

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3
Q

True or False: Missense mutations can lead to loss or gain of function due to changes in amino acid sequence while a non-sense mutation can lead to truncated mRNA or protein due to insertion of a stop codon

A

True

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4
Q

Early stop codon, shifting of the reading frame, or indels of 1 or 2 nucleotides are a result of which mutation?
A. Missense
B. Nonsense
C. Frameshift

A

C. Frameshift

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5
Q

Unstable mutant mRNA/proteins, or mRNA skipping exon, or mutation at junction of intron/exon is a result of which type of mutation?
A. Splicing site mutation
B. Frameshift mutation
C. Nonsense mutation
D. Missense mutation

A

A. Splicing site mutation

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6
Q

What happens when aberrant methylation occurs?

A
  • Gene is repressed (DNA methylation occurs at promoter)
  • There is no mutation in gene body
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7
Q

Which is the only mutation that does not result in decreased expression of mRNA?

A

Missense mutations

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8
Q

_____: Re-introduction of normal (wild type) version of mutated gene to correct a specific condition. Typically used when lack of expression or LOF mutation of a gene causes pathology.

A

Gene Augmentation/Replacement Therapy

Note: Viral Vectors containing recombined human genes are commonly used!

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9
Q

True or False: Once viral vectors are administered for gene augmentation/replacement therapy, they can replicate in other human tissues

A

False - they cannot replicate or infect other cells

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10
Q

For Gene Augmentation, integration or non-integration of virus depends on type of ___

A

virus

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11
Q

____ expression: When a virus is not integrated

A

Episomal

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12
Q

True or False: All the viruses used in gene augmentation/replacement therapy are integrated

A

False - they are not ALL

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13
Q

True or False: There are size restrictions to consider when attempting gene augmentation/repair

A

True

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14
Q

What is a potential problem associated with gene augmentation/replacement?

A

Insertional mutagenesis

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15
Q

True or False: Exogenous control of gene expression is lost in the transgene

A

False - endogenous control is lost

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16
Q

Why is it possible that proliferating tissues may lose the transgene?

A

Non-proliferating tissues are hard to transduce

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17
Q

Which condition is autosomal recessive and associated with adenosine deaminase deficiency?

A

SCID (severe combined immunodeficiency)

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18
Q

ADA (adenosine deaminase) is required for which pathway?

A

Purine salvage pathway

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19
Q

People with SCID’s have trouble making ___, which leads to lymphocyte development problems
A. pyramidines
B. purines
C. nucleotides

A

B. purines

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20
Q

Although bone marrow transplants and extracted lymphocyte gene replacement were somewhat successful at treating SCIDS, which treatment provided long-lasting success?

A

Extracted bone marrow stem cells viral gene replacement therapy

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21
Q

Why do ~20% of SCID’s patients develop leukemias?

A

Insertional mutagenesis

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22
Q

Strimvelis is the EMA approved drug to treat which condition?

A

SCID

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23
Q

True or False: Transgenes typically have a weak promoter/enhancer, both of which are typically euchromic

A

False - transgenes typically have STRONG promoter/enhancer, both of which are EUCHROMIC

24
Q

The introduction of exogenous DNA into cells comes with the possibility the exogenous DNA will be incorporated into genome via _____ _____

A

non-homologous end joining (NHEJ)

25
Q

Where can exogenous virus DNA land?

A
  1. Promoter of oncogene (over-expression) or repressed gene (over-expression)
  2. Within sequence of TS (thereby: inactivating it)
26
Q

_____ is the most common form of childhood blindness. It occurs when RPE65 (isomerohydrolase) is mutated.

A

Leber Congenital Amaurosis

27
Q

True or False: Patients with mutated RPE65 are unable to regenerate chromophores for vision

A

True

28
Q

Luxturna is a gene therapy for treatment of which condition?
A. Leber Congenital Amaurosis
B. SCID’s

A

A. Leber Congenital Amaurosis

29
Q

Adeno-associated virus (AAV) vectors encodes a WT copy of RPE65 and is used to treat which condition?

A

Leber Congenital Amaurosis (LCA)

30
Q

Which type of therapy is employed when a disease state arises due to expression of a mutated gene (dominant negative or GOF) or the expression of a WT gene that should be repressed?
A. Gene Augmentation/Replacement Therapy
B. Gene Blocking Therapy

A

B. Gene Blocking Therapy

31
Q

Both Anti-sense and RNAi or siRNA are a type of ______ therapy

A

Gene Blocking Therapy

32
Q

Which type of therapy involves DNA oligonucleotide that is complement to target mRNA, which leads binding of oligo to target mRNA to block translation?
A. RNAi
B. siRNA
C. Anti-sense Therapy

A

C. Anti-sense Therapy

33
Q

Which type of therapy involves RNA oligonucleotide complementary to target mRNA. Following this, RISC (RNA-induced silencing complex) binds to oligo, searches for target mRNA, and DEGRADES it?
A. RNAi/siRNA
B. Anti-sense Therapy

A

A. RNAi/siRNA

34
Q

True or False: Therapeutic efficacy will decrease with time when gene-blocking therapy is used

A

True

35
Q

What are the four main problems with Anti-sense and RNAi/siRNA?

A
  1. Off target effects
  2. RNA/DNA degradation
  3. Organ targeting
  4. Limited durability
36
Q

CRISPER/Cas9 system is made up of which two components?

A

sgRNA and Cas9 nuclease (generates ds break!)

37
Q

True or False: Cas9 endonuclease, used in CRISPER/Cas9, can be guided to a genomic locus by DNA

A

False - guided by RNA

38
Q

To use CRISPR, what is the only component needed to be designed for a specific locus?
A. RNA fragment
B. DNA fragment
C. Protein fragment
D. cDNA

A

A. RNA fragment

39
Q

True or False: CRISPR/Cas9 is efficient and accurate

A

True

40
Q

Which part of the CRISPR machinery generates a double stranded break?
A. SgRNA
B. Cas9

A

B. Cas9

41
Q

In CRISPR, how is double stranded break repaired?

A

NHEJ

42
Q

Once indels are generated using CRISPR, the indels generate a ____ mutation

A

frameshift mutation

43
Q

True or False CRISPR allows for the activation of target gene

A

False - allows for inactivation

44
Q

True or False: Gene inactivation is possible in the lab, but gene editing is more commonly used (as in CRISPR)

A

False - CRISPR uses gene inactivation but gene editing is only possible in the lab

45
Q

True or False: Gene editing has low efficiency, non-proliferating cells do not do HR, and a template must be reintroduced

A

Tru

46
Q

Problems with CRISPR?

A
  1. Template must be introduced
  2. Template / CRISPR/CAS9 pushes capacity of delivery system
  3. Many cells that need to be corrected are differentiated and quiescent (not cycling) - meaning HR is greatly reduced
47
Q

Mutations in HBB can lead to ____ disease

A

Sickle Cell Disease

48
Q

Retroviral transduction with wild-type ___ and wild-type ___ can be used to treat SCD

A

HBF and HBB

49
Q

In sickle cell disease, CRISPR/Cas9 inactivation of BCL___, a repressor of HBF (fetal hemoglobin), can be used for treatment
A. BCL10A
B. BCL11A
C. BCL12A

A

B. BCL11A

50
Q

True or False: Retroviral vectors integrate into host genome

A

True

51
Q

Which virus is a transduction vector that allows for episomal expression?

A

Adenoviral Vectors and AAV (adeno-associated virus vectors)

52
Q

True or False: Lentiviral vectors are RNA viruses that integrate into host’s genome (e.g HIV)

A

True

53
Q

What is the main problem with viral delivery?

A

Insertional mutagenesis

54
Q

Are changes created using gene therapy permanent?
Inheritable?

A

Permanent, but not inheritable

55
Q

Which technique does 23 and me use for genetic testing?

A

Genotyping by array
- gene probes allow for detection of KNOWN variants

56
Q

Which genetic testing technique is expensive, but allows one to sequence all exons in a sample and identify gene variants, mutations, etc.?
A. Genotyping by array
B. Exome Sequencing
C. Whole Genome Sequencing

A

B. Exome Sequencing

57
Q

True or False: Whole genome sequencing is the most expensive form of genetic testing. It allows for sequencing ALL DND in a sample and identify gene variants, mutations, etc.

A

True

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