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genetics 1 > Bocian Clinical Syndromes > Flashcards

Bocian Clinical Syndromes Flashcards

1
Q

What is triploidy

A

69 chromosomes

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2
Q

Describe the chromosome constitution of triploidy

A

69,XXY - 60%
69, XXX - 35%
69, XYY - 5%

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3
Q

Describe the etiology of triploidy

A

Most (65%) due to dispermy
Many (25%) due to fertilization with a diploid sperm (mitotic failure during meiosis)
Some (10%) due to fertilization with a diploid egg (failure to shed a polar body)

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4
Q

Two types of Trisomy 21 genotype

A

47, XY, +21

47, XX, +21

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5
Q

Down Syndrome is names for?

A

Dr. Langdon Down

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6
Q

Symptoms of Down Syndrome

A

Intellectual disabilities, usually mild to moderate

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7
Q

Typical physical features of down syndrome (6)

A
  1. Up-slanting eyes
  2. Small ears
  3. Thin, down-turned lips
  4. Short, broad hands
  5. Single transverse palmar crease
  6. 5th finger—single crease or short middle phalanx (middle segment)
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8
Q

Describe the tone of Down Syndrome

A

Hypotonia (“low tone;” poor muscle tone; “floppiness”)

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9
Q

Down syndrome organ dysfunction?

A

Congenital heart disease (45%)

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10
Q

Lifespan for Down syndrome

A

Essentially normal lifespan if there is no serious heart disease or other complication

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11
Q

Three types of chromosome abnormality in Down Syndrome

A

Nondisjunction
Translocation
Mosaicism

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12
Q

Describe Down Syndrome Nondisjunction

A

Nondisjunction (3 separate copies of chromosome 21)

a) Most patients (95%) have trisomy due to nondisjunction

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13
Q

Describe Down Syndrome translocation

A

Relatively few patients (3%) have translocations; t(14;21) is the most common—half are inherited,
half are de novo (occur for the first time in the patient); must do parents’ karyotypes to determine recurrence risk

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14
Q

Describe Down Syndrome Mosaicism

A

Relatively few patients have mosaicism (2%)

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15
Q

Describe recurrence risk of Down Syndrome

A

Recurrence risk depends on the mechanism (i.e., nondisjunction vs. de novo translocation vs. inherited translocation) and, in cases of nondisjunction, on the mother’s age at the time of the affected baby’s birth

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16
Q

Trisomy 13 is called?

A

Patau syndrome

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17
Q

Genotype for Trisomy 13

A

47, XY, +13

47, XX, +13

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18
Q

Abnormalities of Trisomy 13

A

Multiple anomalies: cleft lip ± cleft palate, polydactyly (extra fingers or toes),
microphthalmia (small eyes), omphalocele, cardiac anomalies, renal anomalies, etc.

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19
Q

Intellectual level of Trisomy 13

A

Severe intellectual disabilities

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20
Q

Lifespan of Trisomy 13

A

Severely shortened lifespan (few reach past 6 months)

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21
Q

Recurrence risk of Trisomy 13

A

Recurrence risk depends on the mechanism (i.e., nondisjunction vs. de novo translocation vs. inherited translocation) and, in cases of nondisjunction, on the mother’s age at the time of the affected baby’s birth

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22
Q

Trisomy 18 is also called?

A

Edwards syndrome

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23
Q

Trisomy 18 genotype

A

47, XY, +18

47, XX, +18

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24
Q

Abnormalities of Trisomy 18

A

Clenched hand position and typical facial features

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25
Q

Intellectual level of Trisomy 18

A

Profound intellectual diability

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26
Q

Lifespan of Trisomy 18

A

Severely shortened lifespan, most die before 1 year

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27
Q

Recurrence risk of Trisomy 18

A

Recurrence risk depends on the mechanism (i.e., nondisjunction vs. de novo translocation vs. inherited translocation) and, in cases of nondisjunction, on the mother’s age at the time of the affected baby’s birth

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28
Q

Genotype of Turner syndrome

A

45,X

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29
Q

Gender of Turner syndrome

A

Occurs only in females

30
Q

Phenotype of Turner syndrome

A

Physically and behaviorally female, even though they have only one “sex” chromosome

31
Q

Intelligence of Turner syndrome

A

Normal intelligence

32
Q

Stature of Turner syndrome

A

Short stature

33
Q

Describe gonads in Turner syndrome

A

Ovarian dysgenesis (“streak ovaries”) and infertility in most

  1. Premature ovarian degeneration accounts for infertility
  2. Most will not undergo puberty without hormone replacement
34
Q

Describe abnormalities of Turner syndrome

A

Fetal and congenital edema, cystic hygroma (a fluid-filled sac, usually over the neck), cardiac anomalies, renal anomalies, pedal edema (puffy feet) in the newborn

35
Q

Most Turner syndrome have genotype

A

45,X

36
Q

Recurrence of Turner syndrome

A

Unlikely

37
Q

Klinefelter syndrome genotype

A

47,XXY

38
Q

Gender of Klinefelter

A

Occurs only in males

39
Q

Phenotype of Klinefelter

A

Physically and behaviorally male

40
Q

Describe abnormalities of Klinefelter

A

Small testes without sperm; gynecomastia (breast enlargement); poor pubertal development
without hormone replacement; tend to have relatively long limbs

41
Q

Virility of Klinefelter

A

Almost all are sterile

42
Q

Intellectual level of Klinefelter

A

earning disabilities,speech delays, and behavior disorders are common

However, Data from postnatal diagnoses are artificially biased toward abnormality

43
Q

Recurrence risk of Klinefelter

A

Recurrence risk depends on the mother’s age at the time of the affected baby’s birth

44
Q

Describe 47, XXX gender

A

Physically and behaviorally female

45
Q

Appearance of 47, XXX

A

Normal appearance

46
Q

Intelligence of 47, XXX

A

Often low-normal intelligence or mild M.R., but many are normal; speech delays, and/or behavior
difficulties common

However, Data from postnatal diagnoses are artificially biased toward abnormality

47
Q

Empiric risk for trisomies is based on? Exceptions?

A

Empiric recurrence risk for trisomies (but not for XYY, Turner syndrome, or structural chromosomal anomalies) is based on the mother’s age at the time of the affected baby’s birth

48
Q

Cri du Chat is known as? Example of?

A

del 5p (Cri du Chat syndrome) – example of a deletion syndrome in which the deletion may be visible microscopically or may be submicroscopic

49
Q

Typical feature of del 5p?

A

Cat-like cry in infancy

50
Q

Intelligence of del 5p?

A

Intellectual disabilites

51
Q

Williams syndrome is an example of?

A

example of a microdeletion syndrome that is always submicroscopic

52
Q

Describe the microdeletion in Williams syndrome. What does it include?

A

Microdeletion of chromosome 7q11.23, including the elastin gene

53
Q

Describe the phenotype of Williams disease

A

Characteristic facial features

Heart defects common (certain types more common than others)

Hypercalcemia (abnormally high calcium in the serum)

54
Q

Describe the behavior of Williams syndrome

A

Characteristic behavioral/neurodevelopmental phenotype
1. Mild-moderate intellectual disabilities (language ability much better than cognitive ability)
2. Distinctive friendly, loquacious personality
F. Recurrence is uncommon (<1%); rarely, the deletion

55
Q

Describe the tone of Prader-Willi syndrome

A

Severe congenital hypotonia (born with very low muscle tone; “floppy”)
1. Causes early, severe feeding difficulties

56
Q

Behavior of Prader-Willi

A

Typical behavioral phenotype

1. As the hypotonia improves, they develop hyperphagia (severe overeating) and obesity

57
Q

Physical features of Prader-Willi

A

Mild, recognizable facial features

  1. Relatively small hands and feet
  2. Hypogenitalism (more recognizable in males)
  3. Short stature
  4. Cognitive impairment, usually mild intellectual disabilities
  5. Behavioral disorders
58
Q

Describe the etiology of Prader-Willi

A

Cytogenetic or molecular abnormality at 15q11-q13 with abnormal DNA methylation analysis

a) Deletion involving the paternally-inherited 15q
b) Maternal uniparental disomy (i.e., both #15’s were inherited from the mother and none from the father)

59
Q

Describe recurrence of Prader-Willi

A

Rare
Higher risk if imprinting control element is at fault
Lesser risk if chromsomal translocation has occured
Minimal risk if from a deletion or uniparental disomy

60
Q

Tone of Angelman syndrome

A

Jerky, “puppet-like” gait; poor balance

61
Q

Physical characteristics of Angelman

A

Microcephaly

Seizures

62
Q

Intellectual level of Angelman

A

Severe intellectual diabilities

63
Q

Behavior of Angelman?

A

Appear unusually happy

64
Q

Etiology of Angelman

A

Cytogenetic or molecular abnormality at 15q11-q13 with abnormal DNA methylation study
a) Deletion involving the maternally-inherited 15q
b) Paternal uniparental disomy for #15 (5%) (i.e., both #15s were inherited from the father and
none from the mother)

65
Q

Angelman mutation?

A

7% or so have mutation in UBE3A gene

66
Q

Recurrence risk of Angelman

A

Depends on mechanism

67
Q

DiGeorge/Velocardiofacial syndrome is known also as?

A

22q11.2 deletion syndrome

68
Q

Characteristics of DiGeorge

A

Markedly variable physical features, but some common patterns

  1. Cleft palate
  2. Heart anomalies common, especially defects of conotruncal development of isolated conotruncal cardiac anomalies
  3. Often have characteristic facial features; a variety of other anomalies
  4. Immune deficiencies
  5. Hypocalcemia (abnormally low serum calcium); due to hypoparathyroidism (poor function of the parathyroid gland, which regulates calcium level)
69
Q

Intelligence of DiGeorge

A

Learning disabilities or mild or moderate intellectual disabilities common, but many have normal
intelligence

70
Q

Recurrence risk of DiGeorge

A

Recurrence risk depends on whether the deletion was inherited or occurred de novo in the patient

Need to test parents even if normal (7% have deletion)

genetics 1 (7 decks)

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