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Tim's Cards > Genetics III - Final > Flashcards

Genetics III - Final Flashcards

1
Q

Down’s Syndrome is Trisomy____.

A

21

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2
Q

_____% Down’s Syndrome involves Trisomy 21

A

95%

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3
Q

Of the 95% of Down’s Syndrome that involve Trisomy 21, ____ % involve ______,____

and _____% involve ______,_____

A

90% maternal meiosis, MI

10% paternal meiosis, MII

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4
Q

What rearrangement occurs in the Acrocentric Chromosomes?

A

Robertsonian Translocation

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5
Q

What are the 5 Acrocentric chromosomes?

A

13, 14, 15, 21, 22

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6
Q

Robertsonian translocations involve ______ hooked together.

A

Acrocentrics

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7
Q

T/F
Balanced Robersonian translocations involve the long arms of 2 acrocentric chromosomes.

(13,14,15,21,22)

A

True

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8
Q

A balanced Robertsonian translocation between chromos 14 and 21 will yield how many total chromosomes?

A

45

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9
Q

If a woman is carrying a balanced Robertsonian translocation between chromos 14 and 21, how many of her gametes will be viable?

A

50%

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10
Q

A woman and her brother are carriers of a balanced Robertsonian translocation (14 and 21) - which has the highest risk to have a child with Down’s Syndrome?

A

Female

***always higher with female

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11
Q

A woman with a balanced Robertsonian translocation between 14 and 21 has a Down’s baby - how many chromosomes does the baby have?

How many copies of 21?

A

46 (NOT 47)

3 copies 21

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12
Q

Most Down’s Syndrome pts have ____ chromosomes

If mother has a translocation of 14 and 21, the Down’s person will have ____ chromosomes

A

47

46

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13
Q

What could explain a man having a baby with Prader-Willi and his sister having a child with Angleman?

A

Balanced Translocation involving chromo 15

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14
Q

What is the Karyotype of Turner syndrome?

A

45, X

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15
Q

How many 45, X (Turner’s) are spontaneously aborted?

A

99%

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16
Q

What is the only viable monosomy in humans?

only viable hemizygous condition

A

Turner Syndrome

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17
Q

How many Barr bodies would you see in Turner’s Syndrome?

A

0

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18
Q

T/F

A Barr body is an inactivated X chromosome in a female and enables Lyonization

A

True

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19
Q

45, X:

A

Turner’s

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20
Q

45, XX t(14;21)

A

phenotypically normal

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21
Q

46, XX

46, XY

A

normal

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22
Q

46, XX, t(14,21), +21

A

Down’s

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23
Q

47, XXY

A

Klinefelters

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24
Q

What is the worst Robinsonian translocation?

A

21 for 21

fusion of chromosome 21

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25
Q

Where does the nondisjunction that creates 47 XYY occur?

**NOT Klinefelters (47 XXY)

A

Male Meiosis II

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26
Q

Nondisjuction in Male Meiosis I will result in:

Nondisjuction in Male Meiosis II will result in:

**sex chromosomes

A

Kleinfelters (XXY)

XYY (or XXX)

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27
Q

7 reasons to have a Karyotype?

A

Ambiguous genitalia (growth, development)

Dysmorphic features

Stillbirth/neonatal death

Fertility problems

Family history

Neoplasia

Pregnancy in advanced maternal age

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28
Q

When is genetic testing for minors usually ok?

A

Conditions manifesting before 18

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29
Q

Mechanism of Type I Osteogenesis Imperfecta W/O Dentinogenesis imperfecta:

A

Haploinsufficiency

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30
Q

Mechanism of Type I Osteogenesis Imperfecta With Dentinogenesis Imperfecta:

A

Dominant Negative

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31
Q

T/F

Type I Osteogenesis Imperfecta With DI (as opposed to without DI) are more likely to have fractures at birth

A

True

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32
Q

What resource is to be used for a patient that needs genetic testing?

A

Genetic Testing Registry

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33
Q

A son has a trait more commonly affecting females - what is the recurrence risk?

(2 things)

A

More than if female was affected

Greater if you have a daughter

34
Q

How many chromosomes in Triploidy?

A

69

35
Q

What is the most common mechanism that produces Triploidy (69 chromos)?

A

2 sperm fertilize ovum

36
Q

What is the Prognosis for Triploidy (60 chromos)?

A

Babies born but don’t live long

37
Q

How many chromosomes in Tetraploidy?

A

92

38
Q

What is the Karyotype in tetraploidy?

A

92, XXXX

or

92, XXYY

39
Q

What is the usual mechanism that creates Tetraploidy?

A

Failure early division/cleavage in zygote

40
Q

What is the Prognosis for Tetraploidy (92 chromos)?

A

Embryos can form - no babies viable

41
Q

How does Tetraploidy compare to Triploidy?

incidence

A

3x Less common

42
Q

How does Triploidy compare to Tetraploidy in terms of incidence?

A

3x More common

43
Q

A phenotype produced by exposure to an environmental agent…

(this can look like a genetic disorder)

A

Phenocopy

44
Q

When multiple genes contribute to a phenotype…

diabetes

A

Polygenic

***each has small contribution

45
Q

When both Genes and the Environment can contribute to a phenotype…

A

Multifactorial

46
Q

What are 3 factors that contribute to the recurrence risk of a multifactorial trait like clefting?

A

Number affected individuals in Family

Severity

If individual is of sex Least affected, recurrent risk higher

47
Q

What is the one major way genetic testing is different from other types of tests?

A

Implications for Family Members

48
Q

Whole Exome sequencing focuses on…

A

Exons

49
Q

What bill prevents genetic discrimination?

*in terms of job attainment and Health insurance

A

GINA

Genetic Info Nondiscrimination Act

50
Q

T/F

Robertsonian translocations are between metacentric chromos

A

False

*acrocentric

51
Q

T/F

Balanced translocation carriers are at risk to have unbalanced offspring

A

True

*often how identified

52
Q

T/F

A 14,21 Robertsonian translocation will have 1/2 unviable gametes

A

True

53
Q

T/F

The normal X will be turn on in a woman with translocation between autosome and X chromosome.

A

False

***apparently bad chromo will take over

54
Q

What is the most likely way a female expressed X-linked recessive disorder?

What is the least likely?

A

Skewed X inactivation

Mutation pseudoautosomal region Y (females don’t have Y)

55
Q

T/F
Skewed X expression, Uniparental disomy, Turner’s, Consanguinity, and Balanced translocation from Autosome to X can all uncover X-linked recessive in Females

A

True

56
Q

Most common mechanism in PWS and AS?

A

Deletion

57
Q

RR if UPD is mechanism of PWS or AS?

A

less than 1/1000

58
Q

RR if inherited methylation defect is mechanism for PWS or AS?

A

50%

59
Q

Prader-Wili Syndrome, which results from either father’s 15 deletion or Uniparental Disomy from mother, is also…

A

Contiguous gene syndrome

60
Q

PWS results from absence of ____ contribution of chromo 15.

AS results from absence of _____ contribution of chromo 15.

A

Father’s

Mother’s

61
Q

Angelman Syndrome can result from a mutation is _______.

A

Single gene

62
Q

What test provides the highest detection rate for PWS and AS?

What test detects deletions?

A

Methylation

FISH

63
Q

If deletion is the mechanism for PWS or AS, what is the recurrence risk?

A

less than 1/1000

64
Q

Compulsive eating and developmental delay are seen in what Syndrome?

A

Prader-Willi

65
Q

Seizures, Ataxia, and an inability to talk are seen in what Syndrome?

A

Angelman

66
Q

If PWS and AS are seen in the same family, what is the most likely mechanism?

A

Translocation

67
Q

T/F

PWS and AS are the best examples of Imprinting in humans

A

True

68
Q

Triploid have how many chromosomes?

Any viable?

Mechanism?

A

69

Die as newborn

2 sperm, 1 ovum

69
Q

Tetraploid fetuses have how many chromosomes?

Viability?

Mechanism?

A

92

No live births

Early cleavage failure

70
Q

p. Gly180Arg:
p. Gly180*
p. Gly180Gly
p. Gly180Serfs*4

A

Missense

Nonsense

Silent

Frameshift

71
Q

T/F

Whole exome sequencing detects mutations in coding exons

A

True

72
Q

Human disorder = Male Calico Cat

A

Klinefelter’s

73
Q

Different Clinical phenotypes caused by mutations in the Same Gene is…

A

Clinical Heterogenicity

74
Q

T/F

Mito DNA links a woman to all her children and her daughter’s descendants

A

True

75
Q

Fragile X:

Huntington’s:

Freidreich ataxia:

Myotonic dystrophy

A

5’ UTR

1st Exon

Intron

3’ UTR

76
Q

What is the only Autosomal Recessive disorder currently known to be caused by a Trinucleotide repeat?

A

Freidreich Ataxia

77
Q

If a disorder has 1000’s of repeats it does not occur in the _______.

If a disorder has hundreds of thousands of repeats, it can be detected with _______

A

Coding region

Southern Blot

78
Q

T/F

Minors are only tested for disorders occurring in childhood

A

True

79
Q

What major disorder is due to a missense mutation - one AA for another?

A

Sickle Cell Anemia

80
Q

Would a pt with know sickle cell go through chromosome analysis?

A

No.

Cause knows - no need

81
Q

Different mutations, same locus, similar phenotype:

Different phenotypes, mutations in same gene:

Different mutations, different gene (locus), similar phenotype:

Different expressions of mutant allele:

A

Allelic heterogeneity

Clinical heterogeneity

Locus heterogeneity

Variable expressivity

Tim's Cards (140 decks)

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