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AUC Med > MCB 3rd Unit 2 > Flashcards

MCB 3rd Unit 2 Flashcards

1
Q

What gene mutation results in sickle cell disease? What mutation does this cause?

A

A->T transversion in HBB beta globin encoding gene
Causes missense mutation E6V
Amino acid 6: glutamic acid (E) -> Valine (V)

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2
Q

What mutation causes cystic fibrosis?

A

Delta F508

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3
Q

A process used for detecting DNA bands of a specific sequence and determining their size is:

A

Southern blotting

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4
Q

In Southern blotting, DNA fragments are separated based on ___ and detected by ____.

A

Size, hybridization

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5
Q

What does RFLP stand for?

A

Restriction Fragment Length Polymorphism

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6
Q

What process can be used to discriminate between alleles if a mutation/polymorphism changes the size of the DNA fragments?

A

Southern blotting

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7
Q

What is a RFLP?

A

A polymorphism that results in a change in size of a restriction fragment. A subset of SNP’s that happen to fall within a restriction site (create or destroy)

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8
Q

What are SNP’s?

A

Single-Nucleotide Polymorphisms

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9
Q

Besides SNP’s, what other ways can RFLP’s be formed?

A

Chromosomal rearrangement, Deletion/insertion between two restriction sites,
Full gene deletion

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10
Q

What is the mode of inheritance of hemophilia?

A

X-linked recessive

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11
Q

Hemophilia A is a defect in factor ___

A

VIII (F8 gene)

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12
Q

Hemophilia B is a defect in factor ___

A

IX (F9 gene)

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13
Q

~40% of hemophilia A cases are caused by____ which changes the distance between restriction sites, thus changing the fragments on Southern blot.

A

Inversion d/t homologous recombination of repetitive elements near the F8 gene

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14
Q

If all exons are present, can standard PCR tests detect a chromosomal inversion?

A

No

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15
Q

Nail-Patella syndrom is a result of what gene mutation?

A

LMX1B

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16
Q

What is the mode of inheritance of NPS?

A

Autosomal dominant

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17
Q

What can be used to track a mutation in a family?

A

RFLP’s

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18
Q

What is ASO hybridization?

A

Allele-Specific Oligonucleotide Hybridization

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19
Q

What is ASO hybridization used for?

A

Detecting sequence variants

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20
Q

How specific is ASO hybridization?

A

Can discriminate between sequences differing by a single base

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21
Q

ASO hybridization can be automated, and is useful in screening for mutations that are:

A

Frequent, such as CF and beta-thalassemia

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22
Q

What probe is used for ASO hybridization?

A

Oligonucleotides, one for each variant (wt and m)

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23
Q

What is the mode of inheritance for DMD and BMD?

A

XR

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24
Q

More residual protein function leads to more/less severe disease

A

Less

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25
Q

What is the mode of inheritance for Nail-Patella Syndrome?

A

AD

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26
Q

RFLP uses the principle of ____ to track mutations near a restriction site in a family

A

Linkage

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27
Q

The linkage tracked in an RFLP is ___ specific

A

Family

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28
Q

In ASO Hybridization, do we need to know the mutation?

A

Yes

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29
Q

Which type of diagnostic test uses dot blots?

A

ASO Hybridization

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30
Q

Why are only short ASO probes used?

A

Increase specificity, decrease mismatches which would be more stable with a long probe

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31
Q

What is the mode of inheritance for PKU

A

AR

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32
Q

In vitro exponential amplification of specific DNA sequences is called:

A

PCR

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33
Q

What is Taq

A

A Thermostable DNA polymerase

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34
Q

The three steps of a PCR cycle are:

A

Denaturing
Extension
Annealing

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35
Q

The upper limit of PCR in diagnostic labs is:

A

~1kb

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36
Q

A patient with sickle cell disease will have ___ reticulocytes and ___ hemoglobin

A

high, low

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37
Q

Southern Blot, RFLP, FISH, PCR, and CGH all rely on the principle of:

A

Hybridization

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38
Q

What is the inheritance pattern of sickle cell disease?

A

AR

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39
Q

Hemolytic anemia and swelling of the hands and feet are symptoms of:

A

Sickle cell disease

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40
Q

Sickle cell trait is displayed by people who are:

A

Heterozygotes/carriers

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41
Q

Most cases of Turner syndrome are due to a loss of a chromosome before/after fertilization (mosaicism)

A

after

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42
Q

A PCR based alternative to ASO hybridization

A

Allele-specific PCR

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43
Q

What type of PCR can be used to scan for commonly deleted exons?

A

Multiplex PCR

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44
Q

Define MLPA

A

Multiplex Ligation-dependent Probe Amplification

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45
Q

What is MLPA used for?

A

Detecting copy number variation

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46
Q

Give two examples of what MLPA can be used to detect

A

Deletions in DMD

Duplications in Down Syndrome

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47
Q

What are four advantages of MLPA?

A

High-throughput
Quantitative
Fast
Cost-effective

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48
Q

What can Southern blot identify that MLPA and CGH cannot?

A

Balanced chromosomal rearrangements (such as F8 in hemophilia A)

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49
Q

What three sequences are necessary for a MLPA probe?

A

Exon complimentary
Stuffer
Standard PCR binding sites

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50
Q

In an MLPA, the number of probe ligation products is a measure of the number of:

A

Target sequences

51
Q

What does “FISH” stand for?

A

Fluorescence In-Situ Hybridization

52
Q

What technique(s) is/are useful in detecting small deletions?

A

ASO

PCR

53
Q

What technique(s) is/are useful in detecting medium deletions

A

PCR
Southern blotting
MLPA
CGH

54
Q

What technique(s) is/are useful in detecting large deletions?

A

Southern blotting
MLPA
CGH

55
Q

What technique(s) is/are useful in detecting very large deletions

A

FISH

56
Q

What is the target of FISH?

A

Cellular chromosomal DNA

57
Q

What is the probe used in FISH?

A

BACs

58
Q

FISH is useful for detecting:

A

Known chromosomal rearrangements

59
Q

What process can be used to detect unknown chromosomal rearrangements?

A

Spectral Karyotyping (SKY)

60
Q

22q11 deletion syndrome, also called ___, results in “CATCH22” symptoms

A

DiGeorge Syndrome

61
Q

What are the CATCH22 symptoms?

A 
Cardiac defects
Abnormal facies
Thymic hypoplasia
Cleft palate
Hypocalcemia from parathyroid aplasia
22nd chromosome
62
Q

What does CGH stand for?

A

Comparative Genome Hybridization

63
Q

What is the gold standard for mutation identification and should identify any single base substitution?

A

DNA sequencing

64
Q

Beta thalassaemia is due to what type of mutation in the beta-globin gene?

A

Null

65
Q

Tandem repeats are also called:

A

Satellite DNA

66
Q

Backwards slippage of a tri-nucleotide repeat causes an:

A

Insertion

67
Q

Forward slippage of a tri-nucleotide repeat causes a:

A

deletion

68
Q

Slippage of a non triple codon causes a:

A

Frameshift

69
Q

Premature Termination Codons (PTC’s) result in:

A 
RNA degradation (null mutation)
*Truncated in USMLE*
70
Q

The presence of ___ indicate that the ribosome is stalled at a PTC and Nonsense Mediatedd Decay machinery scans the 3 end and triggers RNA degradation

A

Exon Junctional Complexes (EJC’s)

71
Q

Splice sites always start at __ and end at __

A

GT, AG

72
Q

The rate at which new diseases occur is:

A

Incidence

73
Q

The proportion of the population affected is:

A

Prevalence

74
Q

Most diseases which involve enzymes and transporters are:

A

Recessive

75
Q

Most diseases which involve structural proteins and transcription factors are:

A

Dominant

76
Q

Variation in a trait or clinical presentation of a disease is called:

A

Phenotypic (clinical) heterogeneity

77
Q

What are the two types of genetic heterogeneity (which may cause phenotypic heterogeneity)?

A

Allelic and locus heterogeneity

78
Q

What is the term describing when a variety of mutations occuring on the same gene cause the same disease?

A

Allelic heterogeneity

79
Q

What is the term describing when the same mutation within a variety of genes may cause the same disease?

A

Locus heterogeneity

80
Q

Gower’s maneuver, calf pseudohypertrophy, and high creatine kinase are typical signs of:

A

DMD

81
Q

One way to distinguis BMD from DMD at a young age is:

A

Ability to elevate head

82
Q

The inheritance pattern and mutations resulting in DMD and BMD are:

A

X-linked recessive, dystrophin

83
Q

A disease caused by enzyme deficiency is called an:

A

Enzymopathy

84
Q

What are the two causes of disease in enzymopathies?

A

Substrate accumulation, product deficiency

85
Q

What is an AR form of hyperphenylalaninemia involving a deficiency of PAH resulting in intellectual disability?

A

Phenylketonuria (PKU)

86
Q

How many clinical variants of PKU exist?

A

3, Classic, variant, and non-PKU hyperphenylalaninemia

87
Q

What type of heterogeneity does PKU express?

A

Allelic

88
Q

In some cases of PKU, ___ supplementation is necessary to create neurotransmitters and prevent mental retardation

A

BH4

89
Q

General hyperphenylalaninemia expresses what type of heterogeneity?

A

Locus:
PAH (PKU)
2 genes for BH4 synthesis, 2 genes for BH4 recycling

90
Q

What is the mode of inheritance for Oculocutaneous albanism?

A

AR

91
Q

What is the mechanism for oculocutaneous albanism?

A

OCA1 gene: tyrosinase deficiency

OCA1B gene: milder

92
Q

What is the mode of inheritance for maple syrup urine disease?

A

AR

93
Q

What is the mechanism for maple syrup urine disease?

A

Deficiency of BCKDC, defective metabolism of branched chain amino acids (Val, Leu, Ile)

94
Q

The three mechanisms of dominance are:

A

Haploinsufficiency
Gain of function mut.
Dominant negative mut.

95
Q

In the mechanism ____, expression from one copy of an allele is not enough to meet physiological requirements and produce a normal phnotype

A

Haploinsufficiency

Loss-of-function

96
Q

What is the mutated transcription factor resulting in NPS?

A

LMX1B

97
Q

What is defined as the probability that an individual carrying a disease-causing mutation will present with that disease?

A

Penetrance

“All-or-none”

98
Q

What is defined as the probability that individuals carrying the same mutation may present with different phenotypes

A

Variable expressivity

99
Q

NPS has ___ penetrance and variable expressivity

A

Complete

100
Q

FGFR3 encodes a:

A

TKR

101
Q

Achondroplasia is a ___ mutation in FGFR3

A

G380R

102
Q

Mutation for sickle cell?

A

E6V

103
Q

Mutation for cystic fibrosis?

A

Delta F508

104
Q

G380R mutation causes:

A

Achondroplasia

105
Q

The G380R mutation results in a _-of-function

A

Gain

106
Q

Mutation resulting in cleidocranial displasia is:

A

Runx2

107
Q

What is the function of cystein that no other amino acids have?

A

Formation of disulfide bonds

108
Q

When the mutant gene product interferes with the function of the normal gene product the mutation is called:

A

Dominant negative

109
Q

The best example of dominant negative mutations involve ___ proteins

A

Structural

110
Q

The a.a. triplet that forms collagen involves glycine and usually:

A

Proline and hydroxyproline/lysine

111
Q

Hydroxylation, glycosylation, and triple helix winding of collagen occurs in the:

A

ER/Golgi

112
Q

Propeptide cleavage to tropocollagen and fibril assembly of collagen occurs in the:

A

ECM

113
Q

Formation/winding of collagen occurs ___ to ___.

A

C terminus to N terminus

114
Q

What mutation type leads to type I OI?

A

Null mutation d/t haploinsufficiency

115
Q

What mutation type leads to type II-IV OI?

A

Missense, Dominant negative

116
Q

Which type of OI is the most mild? The most severe?

A

I, II

117
Q

OI usually involves substitutions of which amino acid?

A

Glycine

118
Q

AD polydactyly (as well as holoprosencepahly) is caused by mutations in:

A

SHH

119
Q

AD polydactyly is linked to an insertion in the intron of ___ in SHH, which is an enhancer in the gene.

A

LMBR1

120
Q

A mutation in Sox9 will lead to an AD disease called:

A

Campomelic dysplasia

121
Q

Symptoms of campomelic dysplasia include:

A

Skeletal abnormalities, 46XY karyotype with female genitalia

122
Q

Lactose intolerance (as well as campomelic dysplasia and AD polydactyly) is caused by a mutation in the ___ section of a gene

A

Enhancer

123
Q

A deletion syndrome involving 7q11.23 and multiple genes including Elastin (ELN) is:

A

Williams, or Williams-Beuren Syndrome (WBS)

124
Q

If different missense mutations yield distinct phenotypes, then the mutation must be ___-of-function

A

Gain

AUC Med (12 decks)

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