Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MS1 Fall > Genetics 21 - 30 > Flashcards

Genetics 21 - 30 Flashcards

1
Q

Non-directiveness

A

Genetic counselors are not supposed to tell patients whether they should or should not undergo genetic testing. They should also avoid implicit and explicit judgments about what the parents should do if results are obtained

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

cfDNA

A

cell-free placental DNA

It’s found in fragments in the maternal blood, and for some aneuploidies cfDNA screening is more accurate than prior screenings

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Problems with expansion/availbility of cfDNA testing to the general population

A

There are not enough genetic counselors to provide adequate counseling before & after testing and decisional support

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

PPV

A

Positive Predictive Value in cfDNA testing. Depends on the population incidence of the condition tested.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Risks of IVF

A

multiple pregnancies, ectopic pregnancy, cancellation, ovarian hyperstimulation syndrome, mechanical injury to other organs during egg retrieval, greater risk of premature delivery or c-section

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How is pre-implantation genetic diagnosis (PGD) performed?

A

A single cell from the 8-cell stage is removed by puncturing the zona pellucida and aspirating a cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

PGD tests that can be performed

A

karyotyping, FISH, PCR to amplify specific genomic regions, and whole genome amplification followed by microarray or deep sequencing to look at copy number variation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What phase, according to the bogus study, must oocytes be in for no mosaicism to show up in embryos after a CRISPR/sperm injection?

A

M-phase

S-phase sperm + CRISPR injections showed an increase in WT/WT embryos produced, but did not eliminate mosaics.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Problem with the m-phase theory in CRISPR technology?

A

The maternal and paternal genomes are confined to separate compartments for at least a day post fertilization, so there is no way Cas9 is using the maternal genome as a template to repair the paternal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Medium-chain acyl-CoA dehydrogenase deficiency (MCADD)

A

A rare, autosomal recessive genetic condition where a person has problems breaking down fatty acids for energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Genetic basis for MCADD?

A

Mutation in the ACADM gene that codes for the medium-chain acyl-CoA dehydrogenase enzyme. this enzyme is essential for fatty acid oxidation, specifically medium-chain fatty acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Signs and symptoms of MCADD?

A

Vomitting, lack of energy, low blood sugar.

Serious complications include seizures, breathing difficulties, liver problems, brain damage, coma, and sudden death.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Treatments for MCADD

A

Avoid periods of fasting, proper nutrition & exercise, avoid hypoglycemia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Constitutional (germline) =

A

inherited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Clonal expansion

A

cancers start from a somatic cell that accumulates favorable genetic and epigenetic mutations`

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Two cancer models

A
  1. Stochastic Cancer Model

2. Cancer Stem Cell Model

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Stochastic Cancer Model

A

Normal somatic cell with normal germline genotype. Mutations collect (image with green then red, yellow, purple) until there are a collection of mutations and the cell phenotype is less differentiated

Every malignant cell can re-seed a new tumor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Cancer Stem Cell Model

A

First mutation occurs in a somatic stem-type cell. It is more likely to evade therapy than evolved tumor cells and then repopulate the tumor.

Can’t ever guarantee that its gone so you undergo screenings to make sure its at bay

Only the original tumor stem cells can re-seed tumors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What complicates interpretation of DNA/chromosomes from tumors?

A

Mosaicism. Mix of different cell types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Cancer Immunotherapy

A

stimulate the patient’s own T cells to specifically attack tumor cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Oncogenes

A

promote cell proliferation

just need one affected copy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Mutator genes

A

subtype of tumor suppressor genes

involved in DNA mismatch repair; “a gene that increases the mutation frequency of other genes”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Types of oncogene amplification

A
  1. double minute chromosomes (small chromosome fragments)
  2. homogeneously staining regions (HSRs); gene amplified in situ in original chromosome
  3. amplification below the cytogenetic level - ex. just four copies. Won’t see on FISH or karyotype but will on CGH array
24
Q

Mechanisms of activation of oncogenes

A
  1. amplification
  2. activating point mutation
  3. chromosomal translocation (philadelphia chromosome)
  4. retroviral insertion (T cell leukemia example)
  5. hypomethylation of oncogene promoter
  6. aberrant mRNA splicing or mutations leading to use of alternative promoters/polyadenylation sites (different isoforms)
25
Q

Are oncogene activations somatic or germline?

A

Typically somatic but can be germline (RET mutation leading to MEN1, MEN2).

26
Q

Mechanism of gene inactivation in tumor suppressor genes

A
  1. deletion (loss of heterozygosity)
  2. other small genetic changes
  3. hypermethylation of promoter
27
Q

tumor suppressor genes

A

encode transcripts/proteins that prevent cells from dividing too frequently or from surviving inappropriately (pumping the brakes)

28
Q

Inheritance pattern of mutated tumor suppressor gene?

A

Autosomal dominant inheritance of cancer risk

note: mechanism is recessive at the tumor cell level

29
Q

Neurofibromatosis 1 (NF1)

A

autosomal dominant condition, ~1/3500 worldwide

Mutation in NF1 tumor suppressor gene whose protein, neurofibromin, normally inhibits RAS

Fully penetrant, variable expressivity

30
Q

CGH vs. SNP arrays in testing for deletions

A

CGH can detect a deletion and estimate length of the deletion while SNP array can characterize deletion but will also tell you which allele is lost

31
Q

Familial Adenomatous Polyposis

A

typical tumor suppressor system; inherited APC gene mutation.

Colon polyps are results of independent 2nd hits to those cells

32
Q

Hereditary non-polyposis colon cancer (HNPCC)

A

aka Lynch syndrome

HNPCC tumors show instability in length of some microsatellite alleles; novel alleles in the tumor are observed that are not part of the germline genotype (mutator phenotype)

33
Q

mutator phenotype

A

achieved by the inactivation of so called mismatch repair (MMR) genes. These genes are important in maintaining the accurate repeat units of microsatellites

novel alleles are observed

34
Q

Properties of malignant cells

A

immortal (never senesce)
can grow without being provided usual growth factors
avoid programmed cell death (apoptosis)
can induce blood vessel formation to feed tumor
ability to invade adjacent tissues, which can lead to ability to metastasize

35
Q

What is the major risk factor for colon cancer?

A

Age

90% of “usual” cases are after age 50

36
Q

When are screening tests performed?

A

Before a person has symptoms

if its after symptoms are present then you are conducting a diagnostic workup

37
Q

In CRC, what is the first hit in adenoma to carcinoma?

A

APC tumor suppressor gene is inactivated

Subsequent hits are to K-Ras, 18q, TP53, etc

38
Q

What percentage of people with FAP develop CRC by age 40?

A

100%

Treatment is prophylactic coloprotectomy by 20yo

39
Q

What is a hallmark of Lynch Syndrome?

A

multiplicity of cancers

40
Q

What are the clinical features of Lynch Syndrome?

A

predominately proximal colon cancers, flat polyps, progression from polyp to cancer in 2-3 years

41
Q

What is Amsterdam/Bethesda criteria?

A

Method of diagnosis for Lynch Syndrome.

3 - 2 - 1

3 family members with Lynch synd cancers
2 first degree relatives
1 CRC before age 50

42
Q

What is the only type of down syndrome known to have a hereditary link?

A

translocation

43
Q

What laws protect genetic information?

A

HIPAA and state laws

44
Q

What is the Genetic Information Non-Discrimination Act (GINA)?

A

A law that prohibits discrimination on the basis of genetic information, by health insurers and employers

45
Q

What types of insurances do NOT fall under GINA protection?

A

Life insurance, disability insurance, and long term care insurance

46
Q

What is not protected by GINA?

A

Analysis of proteins or metabolites that are related to a manifested disease that can be reasonably be detected by a trained healthcare professional

47
Q

Sensitivity

A

Out of those people who have a disease, how many tested positive (a true positive rate)?

D / (C+D)

48
Q

Specificity

A

Out of those people who do NOT have a disease, how many people tested negative (a true negative rate)?

A / (A+B)

49
Q

What is a Receiver Operating Curve?

A

Plotting the sensitivity (y-axis) against the specificity (x-axis)

a perfect test would be a right angle

50
Q

What traits will an ideal medical test have?

A

Sensitivity, specificity, a high positive predictive value (PPV), and inexpensive

51
Q

What is a consequence of screening with low specificity?

A

Anxiety on the part of patient’s if they receive a false positive (and maybe they won’t follow up!)

52
Q

What does it mean when genotype = phenotype?

A

100% penetrance

53
Q

Relative risk

A

Ratio of two probabilities

Probability of disease in group 1 divided by the probability of disease in group 2

54
Q

How do we find genes and pathways in a complex disease?

A
  1. linkage studies in families
  2. animal models
  3. GWAS (large population associations)
  4. isolated population studies
55
Q

What can affect the relative risk for disease?

A

Less than 100% penetrance, multiple genes, and interactions with the environment

56
Q

Why measure protein to diagnose a disease over just measuring the DNA

A

If there are many different mutations that can lead to disease BUT the disease has a characteristic LACK of a protein, then testing for the protein might make the most sense

MS1 Fall (23 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions