Brainscape's Knowledge GenomeTM

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


See full index

T1 - Phase 1 - Integrated (II) > Endo/Repro - Genetics - Autosomes; Sex Chromosomes; Uniparental Disomy > Flashcards

Endo/Repro - Genetics - Autosomes; Sex Chromosomes; Uniparental Disomy Flashcards

1
Q

What are the three categories of genetic disorder?

A
  • Chromosomal
  • Metabolic
  • Syndromic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define: mosaicism.

A

An individual with two genetically distinct cell lines coming from a single zygote

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

True/False.

Mosaicism results from a meiotic non-disjunction event occuring in the pre-zygotic phase.

A

False.

Mosaicism results from a mitotic non-disjunction event occuring in the post-zygotic phase.

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

Define: nondisjunction.

A

The failure of chromosomes to separate during meiosis I or mitosis (or sister chromatids during meiosis II)

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

What is here described?

The failure of two homologous chromosomes to separate during meiosis I, or two chromatids of a chromosome to separate in meiosis II or mitosis resulting in one daughter cell with two homologous chromosomes and the other with none.

A

Nondisjunction

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

What are three infant S/Sy that indicate you might need to check for chromosomal abnormalities?

A
  • Growth restriction
  • Structural abnormalities (especially >1)
  • Developmental delay, or mental retardation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What type of genetic disorder is characterized by some mixture of the following?

  • Growth restriction
  • Structural abnormalities, especially more than one
  • Developmental delay, or mental retardation
A

Chromosomal abnormalities

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

What are two common causes of trisomies?

A
  • Nondisjunction (often due to advanced maternal age)
  • Translocation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the most common form of chromosomal translocation?

A

14;21 Robertsonian translocation

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

What risk of Down syndrome does a woman’s pregnancy carry if the woman is 20?

35?

40?

49?

A
  1. 06%
  2. 3%
  3. 0%
  4. 1%
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

If a woman has given birth to a child with Down syndrome, is there a difference to future pregnancies whether the Down syndrome was caused by trisomy 21 or 14;21 Robertsonian translocation?

A

Yes.

If trisomy 21:

there is a 1% risk until about age 40 (then normal age risks)

If 14;21 Robertsonian translocation:

– de novo: not significantly higher

– maternal carrier: 10-15%

– paternal carrier: 3- 5%

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

What percentage of Down syndrome cases are due to trisomy 21?

What percentage are due to translocations?

What percentage are due to trisomy mosaicism?

A

95%

4%

1%

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

What is the genetic cause of the vast majority of cases of Down syndrome?

A

Trisomy 21 (95%)

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

What are the classical S/Sy of Down syndrome?

A

Mental retardation,

hypotonia, protruding tongue, short stature,

upslanting palpebral fissures, epicanthal folds,

transverse palmar crease, clinodactaly of 5th finger

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

What intestinal and ocular signs are often present in Down syndrome?

A

Intestinal: duodenal atresia

Ocular: speckled iris (Brushfield spots)

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

What cardiac complications often exist in patients with Down syndrome?

A

Atrio-ventricular canal;

VSD

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

True/False.

Individuals with Down syndrome are at a higher risk for Alzheimer’s disease, leukemia, hypothyroidism, and cataracts.

A

True.

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

What is the genetic cause of Edward’s syndrome?

A

Trisomy 18

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

What is the genetic cause of Patau syndrome?

A

Trisomy 13

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

How long do patients with Edward’s syndrome typically live?

A

< 1 year

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

List a few of the common S/Sy of Edward’s syndrome.

How long do these patients typically live?

A

Microcephaly, prominent occiput, low set ears,

clenched hands (index finger overlies 3rd finger)

< 1 year

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

What non-neurological organ system is often severely affected in patients with Edward’s syndrome?

A

>90% have congenital heart disease

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

How common is Down syndrome?

How common is Edward’s syndrome?

How common is Patau syndrome?

A

1/1000

1/10,000

1/15,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the life expectancy for an individual with Down syndrome?

What is a common cause of death?

A

60s

congenital heart disease

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the life expectancy for an individual with Patau syndrome?

A

~85% are < 1 year;

rarely, some may reach adulthood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Describe some of the visible clinical features of Patau syndrome.

A

Cleft lip/palate (midline usually): 70%;

abnormal ears, scalp defects;

polydactyly;

omphalocele

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Describe some of the non-visible clinical features of Patau syndrome.

A

Holoprosencephaly, mental retardation;

congenital heart abnormalities;

single umbilical artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are some of the heart abnormalities associated with Patau syndrome?

A

VSD

PDA

ASD

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Which autosomal monosomies are survivable?

A

None

(unless mosaic with a normal cell line)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is it called if an individual receives an extra 23 chromosomes from one of their parents?

A

Triploidy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

True/False.

Triploidy in humans is an example of genetic imprinting, depending on whether the error was received from the father or the mother.

A

True.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the genetic cause and effect if an individual receives an extra 23 maternal chromosomes (triploidy)?

A
  • Digyny (triploid zygote –> haploid sperm and diploid egg)
  • Small placenta, very growth-restricted fetus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the genetic cause and effect if an individual receives an extra 23 paternal chromosomes (triploidy)?

A
  • Dispermy, paternal nondisjunction
  • Large hydropic placenta (incomplete mole);

3,4 syndactyly, macrocephaly, deformed face, other malformations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Which is more useful in chromosomal analysis, prometaphase or metaphase analysis?

Why?

A

Prometaphase;

improved band resolution + detection of smaller deletions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

A newborn presents with a small face, large nose, and large mouth. The patient shows poor motor tone and is making a high-pitched ‘mewling’ like that of a cat.

What is the diagnosis? What is the cause?

A

Cri-du-Chat syndrome;

microdeletion on chromosome 5p

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Describe Cri-du-Chat syndrome.

A

Affected chromosome: 5p

characteristic newborn cry like a cat;

small face, large nose, large mouth;

failure to thrive, developmental delay, hypotonia

37
Q

Describe the presence of fetal testis on development of the Wolffian or Mullerian ducts.

A

Leydig cells –> testosterone –> mesonephric (Wolffian) differentiation

Sertoli cells –> MIF –> paramesonephric (Mullerian) degeneration

38
Q

What structures are formed due to the effects of fetal testosterone?

What structures are formed due to the effects of fetal dihydrotestosterone?

A

Epididymus, vas deferens, seminal vesicles;

penis, prostate, scrotum

39
Q

Describe the effects of fetal ovaries on development of the Wolffian or Mullerian ducts.

A

Mesonephric (Wolffian) degenerate (due to the lack of testosterone);

paramesonephric (Mullerian) develop (due to the lack of MIF)

40
Q

What adult structures develop from the paramesonephric (Mullerian) ducts?

A

The upper 1/3 of the vagina,

the uterus,

the Fallopian tubes

41
Q

Define: Lyonization.

A

At ~2 weeks post-fertilization, one X chromosome in each cell of the female embryo becomes inactive

42
Q

What process is defined below?

At ~2 weeks post-fertilization, one X chromosome in each cell of the female embryo becomes inactive

A

Lyonization

43
Q

Define: gonadal dysgenesis.

A

Poorly developed or streak gonads due to various causes

44
Q

What term describes the following:

an individual born with both ovarian and testicular tissue.

A

True hermaphroditism

45
Q

List the genetic makeup of each of the following cases:

Kleinfelter’s syndrome

Turner’s syndrome

Trisomy X

Androgen insensitivity

A

47, XXY

45, XO

47, XXX

46, XY

46
Q

What is male pseudohermaphroditism?

A

An XY male with externally ambiguous or feminine genitalia

47
Q

What is female pseudohermaphroditism?

A

An XX female with externally ambiguous or masculine genitalia

48
Q

Classic Turner’s syndrome involves complete loss of what?

A

An X chromosome

(45,X0)

49
Q

Turner’s syndrome can also result from a loss of the X p arm or q arm. Describe the differences.

A

46, XX, Xp-: short stature; congenital malformations

46, XX, Xq-: gonadal dysfunction

50
Q

What medication(s) can be given to treat Turner’s syndrome?

A

Estrogen, progesterone, growth hormone

51
Q

True/False.

Turner’s syndrome leads to the following S/Sy:

cystic hygromas, short stature, cardiac and renal abnormalities, mental retardation, lack of development of secondary sexual characteristics.

A

False.

Turner’s syndrome leads to the following S/Sy:

cystic hygromas, short stature, cardiac and renal abnormalities, average intelligence (no mental retardation), lack of development of secondary sexual characteristics.

52
Q

What is the mechanism of Kleinfelter’s syndrome?

A

Meiotic nondisjunction

53
Q

Describe the development, puberty, and fertility of an individual with Kleinfelter’s syndrome.

A

Development: Normal (tall, thin); IQ slightly less than normal; behavioral problems

Puberty: Small testis; hypogonadism, gynecomastia

Reproduction: Infertile (hylanized tubules; azoospermia)

54
Q

How is Kleinfelter syndrome treated?

A

Testosterone replacement

55
Q

Describe the development and fertility of a 47, XYY male.

A

Development: Normal male; tall; behavioral problems

Fertility: normal

56
Q

What is the cause of 47,XYY defects?

A

Paternal nondisjunction

57
Q

Describe the development and fertility of a 47,XXX individual.

A

Development: Normal female; development: tall; low IQ

Reproduction: Many infertile

58
Q

What is the cause of androgen insensitivity syndrome?

A

No androgen receptor in target cells

59
Q

How do individuals with androgen insensitivity syndrome present at birth?

What is their karyotype?

A

As females;

46,XY

60
Q

Describe the developmental effects of androgen insensitivity syndrome.

A

Development: Feminization; incomplete adrenarche; amenorrhea; small clitoris/labia;

lower 2/3 of the vagina; absent uterus and tubes and mesonephric structures

61
Q

What is the risk of gonadal neoplasia in an individual with androgen insensitivity syndrome?

A

2 - 5%

62
Q

What is the risk of poorly differentiated gonadal tissue in an intraabdominal environment?

A

Increased risk of gonadal carcinoma

63
Q

What should occur if a 46,XY individual has any form of gonadal dysgenesis?

A

Surgical removal of gonadal tissue

64
Q

What do 46,XY/45,X0 and 46,XX/45,X0 karyotypes describe?

A

Male and female forms of mosaic Turner’s syndrome

65
Q

What karyotype is known as a ‘super male’?

What karyotype is known as a ‘super female’?

A

XYY

XXX

66
Q

What gene determines sexual differentiation?

A

SRY

67
Q

What is Fragile X syndrome?

What is the genetic defect?

Which parent is more likely to pass on / worsen this defect?

A

X-linked mental retardation;

CGG repeats in the FMR1 gene;

maternal

68
Q

What are two disorders displaying anticipation?

A

Fragile X syndrome;

Huntington’s disease

69
Q

In working up potential Fragile X syndrome, how can genetic testing be performed?

A

a) Southern analysis — separates trinucleotide repeat segments based on size

b) PCR — will give size of mutation (best for premutations)

Best to do both

70
Q

Define: infertility.

A

(1) Inability to achieve conception or (2) inability to sustain a pregnancy through to live birth

71
Q

What are a few chromosomal abnormalities associated with infertility?

A
  • Turner’ syndrome
  • Kleinfelter’s syndrome
  • X chromosome abnormalities
  • Y chromosome microdeletions
  • Translocations (reciprocal and Robertsonian)
72
Q

True/False.

Some genes are expressed preferentially in either the parental or maternal genotype.

A

True.

73
Q

How is genetic imprinting regulated?

A

Epigenetics (extrinsic to changes in primary nucleotide sequence)

  • DNA methylation
  • Histone modification
  • Non-coding RNAs
74
Q

Define: genetic imprinting.

A

The differential modification of the maternal and paternal genetic contribution to the zygote

75
Q

Define: uniparental disomy.

A

The inheritance of a pair of chromosomes from one parent with no copy of that chromosome from the other parent.

76
Q

Give the term described below.

The inheritance of a pair of chromosomes from one parent with no copy of that chromosome from the other parent.

A

Uniparental disomy

77
Q

Describe the subtype of uniparental disomy below:

Isodisomy

A

Two copies of the same homolog from one parent

78
Q

Describe the subtype of uniparental disomy below:

Heterodisomy

A

One copy of each homolog from the same parent

79
Q

Describe the subtype of uniparental disomy below:

Segmental UPD

A

A segment of a chromosome is present from the same parent

80
Q

Describe trisomy rescue as a cause of uniparental disomy.

A
81
Q

True/False.

All of the following are potential causes of uniparental disomy:

  • Trisomy Rescue
  • Monosomy Rescue
  • Gametic Complementation
  • Somatic Crossing-over
  • Robertsonian Translocation
A

True.

82
Q

70% of cases of Prader-Willi syndrome are caused by a deletion of:

25% of cases of Prader-Willi syndrome are caused by:

5% of cases of Prader-Willi syndrome are caused by:

A

Paternal chromosome 15 genetic material

maternal uniparental disomy of chromosome 15

imprinting center defects

83
Q

What is the basic etiology of Prader-Willi syndrome?

A

Loss of function of a group of genes normally expressed on the paternal chromosome 15

84
Q

What is the basic etiology of Angelman syndrome?

A

Loss of function of a group of genes normally expressed on the maternal chromosome 15

85
Q

What syndrome is caused by a loss of function of a group of genes normally expressed on the maternal chromosome 15?

What syndrome is caused by a loss of function of a group of genes normally expressed on the paternal chromosome 15?

A

Angelman syndrome;

Prader-Willi syndrome

86
Q

Describe the clinical features of Prader-Willi syndrome.

A

Neonatal hypotonia, intellectual impairment, short stature, small hands and feet, hypogonadism, behavior problems, obesity

Facial features: narrow bifrontal diameter, short upturned nose, triangular mouth, thin upper lip, almond-shaped eyes

87
Q

Describe the clinical features of Angelman syndrome.

A

Severe intellectual impairment, seizures, ataxia, paroxysms of laughter, absent speech, wide mouth with protruding tongue, widely spaced teeth

88
Q

70% of cases of Angelman syndrome are caused by a deletion of:

3-7% of cases of Angelman syndrome are caused by:

5-11% of cases of Angelman syndrome are caused by a mutation in what gene?

3% of cases of Angelman syndrome are caused by:

A

Genetic material on the maternal chromosome 15

Paternal uniparental disomy

UBE3A

Imprinting center defect

T1 - Phase 1 - Integrated (II) (23 decks)

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