Final Review Flashcards

1
Q

Fragile X repeat/location:

A

CGG in 5’ UTR

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2
Q

Huntington Disease repeat/location:

A

CAG-coding disorder in exon

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3
Q

Freidreich Ataxia repeat/location:

A

GAA in intron; only autosomal recessive disorder

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4
Q

Myotonic Dystrophy repeat/location:

A

CTG in 3’ UTR

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5
Q

Achondroplasia Inheritance

A

AD or incomplete dominant

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6
Q

Achondroplasia Mutations

A

One mutation accounts for majority of

mutations; most (80%) are de novo (ALWAYS on paternal allele)

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7
Q

Achondroplasia Diagnosis

A

PCR followed by restriction enzyme digestion

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8
Q

p.Gly17Arg:

A

missense mutation

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9
Q

p.Gly17

A

nonsense mutation

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10
Q

p.Leu6Hisfs*3

A

frameshift mutation

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11
Q

101-2A>T

A

Splicing mutation in intron
+at beginning of intron
-at end of intron

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12
Q

Certain genes are only expressed from one parent

A

Imprinting

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13
Q

Inheritance of both alleles from one parent

A

Uniparental Disomy

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14
Q

What’s a risk in during MII in older moms?

A

chromosomal nondisjunction

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15
Q

Average size of a gene?

A

14,000 bp or 14 kb (22,000 genes in genome)

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16
Q

What is 1 cM equivalent to?

A

1,000,000 bp or 1000 kb or 1 Mb

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17
Q

Different phenotypes result from mutations in the same gene

A

Clinical Heterogeneity

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18
Q

Different mutations in the same gene cause the

same phenotype

A

ALLELIC HETEROGENEITY

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19
Q

Mutations in different genes give same phenotype

A

Locus Heterogeneity

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20
Q

where a single gene may cause multiple phenotypic expressions or disorders.

A

pleiotropy

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21
Q

Production of same phenotype by different genetic mechanism

A

Genetic Heterogeneity

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22
Q

an altered gene product that acts antagonistically to the wild-type allele

A

Dominant Negative

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23
Q

What is the underlying molecular mechanism for type I OI with DI?

A

Dominant Negative

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24
Q

In what disorder does nondisjunction always occur in male meiosis II?

A

47, XYY

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25
Q

What percentage of DS is due to trisomy 21 like in karyotype?

A

95% of cases involve trisomy 21
90% involve maternal meiosis, MI
10% involve paternal meiosis, MII

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26
Q

A woman is a carrier of a balanced Robertsonian translocation between chromosomes 14 and 21. How many chromosomes does she have?

A

45

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27
Q

A woman is a carrier of a balanced Robertsonian translocation between chromosomes 14 and 21. On average, how many of her gametes will be viable?

A

50%

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28
Q

The woman with the baby with the translocation has a baby with Down Syndrome. How many chromosomes does this baby have? How many copies of chromosome 21?

A

The baby has 46, with 3 copies of chromosome 21.

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29
Q

A woman and her brother are carriers of a balanced Robertsonian translocation between chromosomes 14 and 21. Who has the highest risk to have a child with Down syndrome?

A

Risk is always higher to a female.

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30
Q

A man has a child with Prader-Willi syndrome. His sister has a child with Angelman syndrome. How do you explain this?

A

They are each carriers of a balanced translocation involving chromosome 15.

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31
Q

Thinking about Turner syndrome: How many are spontantously aborted?

A

99%

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32
Q

What is unique about Turner syndrome?

A

Only viable monosomy in humans

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33
Q

Thinking about Turner syndrome: What would the karyotype show?

A

45, X

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34
Q

How many codons total?

A

64

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35
Q

How many stop codons, and what are they?

A

3: UAA, UAG, UGA

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36
Q

Is the code the same for nuclear and mitochondrial DNA?

A

No

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37
Q

Characteristics of Non-penetrance

A

Affected parent and child while themselves unaffected

38
Q

How can a female have an X-linked recessive disorder?

A
Skewed X activation (most likely)
Assortative mating
Consanguinity 
Uniparental disomy
Turner’s Syndrome
39
Q

Most common mechanism that causes PWS?

A

Paternal 15q11q13 deletion

40
Q

Most common mechanism that causes Angelman’s?

A

Maternal 15q11q13 deletion

41
Q

What is the most efficient method for testing for PWS and AS?

A

Methylation analysis

42
Q

Uniparental disomy has implications for which types of disorders?

A

Imprinting disorders

Recessive disorders

43
Q

What are the components of a PCR?

A
Template
Primer
DNA polymerase
Nucleotides
Buffer (magnesium)
44
Q

Autosomal dominant Mechanisms of action

A

Haploinsufficiency
Dominant negative
Gain of function

45
Q

where a diploid organism has only a single functional copy of a gene (with the other copy inactivated by mutation) and the single functional copy of the gene does not produce enough gene product (typically a protein)

A

Haploinsufficiency

46
Q

Number of PCR cycles required to generate 1 million copies?

A

20

47
Q

Number of PCR cycles required to generate 1 million copies?

A

20

48
Q

45, XX, t(14;21) Phenotypically normal?

A

Normal Female with a balanced translocation between 14 and 21

49
Q

46, XX Phenotypically normal?

A

Normal Female

50
Q

45, X Phenotypically normal?

A

Turner Syndrome

51
Q

46, XY Phenotypically normal?

A

Normal Male

52
Q

47, XXY Phenotypically normal?

A

Klinefelter Syndrome

Tall, sterile male

53
Q

Why would someone have a karyotype performed?

A

growth/ development problems
Dysmorphic features
stillbirth/ neonatal death
Male and female fertility issues
Family history of chromosome abnormalities
Neoplasia
Pregnancy in women of advanced maternal age

54
Q

What is the underlying mechanism for type I OI with DI?

A

Dominant negative: the mutant protein action is overriding normal protein action

55
Q

Describe Triploidy

A

69 chromosomes
Mechanism: fertilization of one ovum by 2 sperms
Babies are born, but don’t live long

56
Q

Describe Tetraploidy

A
92 chromosomes
Karyotype is 92 XXXX or 92 XXYY
Mechanism: failure to complete early cleavage division of a zygote 
Embryos, but no babies
3x less common than Triploidy
57
Q

Phenotype produced by exposure to an environmental agent and looks like a genetic disorder

A

Phenocopy

58
Q

Define Polygenic

A

Multiple genes contribute to phenotype, usually each with a small contribution
Important in complex traits like diabetes

59
Q

When Genes and environment contribute to phenotype

A

Multifactorial

60
Q

What bill was passed to try and prevent genetic discrimination in obtaining a job and health insurance?

A

Genetic Information Nondiscrimination Act (GINA)

61
Q

True or False? Robertsonian translocations are translocations between two metacentric chromosomes.

A

FALSE. They are between two acrocentric chromosomes.

62
Q

True or False? Balanced translocation carriers are not at risk to have unbalanced offspring.

A

FALSE

63
Q

True or False? Of the gametes that a carrier of a 14;21 Robertsonian translocation can make, ½ are not viable.

A

TRUE. Those that end up with monosomy 21, monosomy 14, and trisomy 14 are not viable.

64
Q

True or False? In a female with a translocation between an autosome and the X chromosome, the normal X will be preferentially inactivated.

A

TRUE

65
Q

the best examples in humans of diseases Imprinting

A

PWS and AS

66
Q

Achondroplasia Mutation

A

FGFR3 mutation

67
Q

Example of Synergistic heterozygosity

A

epigenetic factors, and environmental influences may combine with specific genetic mutations to produce
nonsyndromic clefting

68
Q

Chromosome with Centromere in the center of the chromosome

A

Metacentric

69
Q

Chromosome with Centromere slightly towards one end

A

Submetacentric

70
Q

Centromere at one end

A

Acrocentric

71
Q

How long does male gametogenesis last?

A

Lasts 60-65 days, but continues through life

72
Q

spermatids ejaculated per ejaculation?

A

100-200 Million, If your Me about 800million

73
Q

5’UTR=

A

untranslated region “upstream”

74
Q

3’UTR=

A

end “Downstream”

75
Q

How many amino acids have only 1 codon?

A

2, Methionine (AUG) and Tryptophan (UGG)

76
Q

Autosomal Recessive Diseases to remember

A

Sickle Cell Anemia
Cystic Fibrosis
Amelogenesis Imperfecta

77
Q

Autosomal Dominant Diseases to remember

A

Achondroplasia
Neurofibromatosis
Amelogenesis Imperfecta
Hereditary Gingival Fibromatosis

78
Q

Protein does something it doesn’t normally

do (or does its usual job better)

A

Gain of Function

79
Q

Myotonic Dystrophy Mechanism of disorder

A

Mechanism of disorder : Non-coding repeat

CTG repeat in 3’ UTR
Affected have >50 repeats
Anticipation noted

80
Q

Diagnosis in neonates with Myotonic Dystrophy Mechanism of disorder

A
Hypotonia
Facial muscle weakness
Generalized weakness
Club foot
Respiratory insufficiency or failure
81
Q

Diagnosis in adults with Myotonic Dystrophy Mechanism of disorder

A

Muscle weakness of distal leg, hand, neck, and face
Myotonia
Cataracts

82
Q

Myotonic Dystrophy Mechanism of disorder Inheritance

A

Most always inherited from mother, but also possible from father

83
Q

All known polyglutamine disorders are characterized by …

A

progressive neuronal dysfunction that typically begins mid-life, resulting in severe neurodegeneration

84
Q

Hutchinson-Gilford Progeria

A

Due to a de novo mutation
gly→ ser
Affects splicing: new cryptic splice site

85
Q
DNA probes specific for
individual chromosomes,
chromosomal regions, or
genes used to rapidly
diagnose abnormal
chromosome number or
deletions/insertions
A

Fluorescence In Situ Hybridization (FISH)

86
Q

Number of PCR cycles required for
accumulation of specific amt of product
is a reflection of relative amt of nucleic
acid template present in sample

A

Taqman

Or Quantitative PCR

measure the accumulation of PCR product
during the course of the reaction (“real-
time PCR”)

87
Q

translocation between the long arms of 2 acrocentric chromosomes

A

Robertsonian Translocation:

88
Q

Compulsive eating, developmental delay

A

PWS

89
Q

Seizures, ataxia, inability to talk

A

AS

90
Q

Number of PCR cycles required for
accumulation of specific amt of product
is a reflection of relative amt of nucleic
acid template present in sample

A

Taqman Test