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Isaak: Genetics MBS > Lecture 9: Cytogenetics I > Flashcards

Lecture 9: Cytogenetics I Flashcards

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1
Q

What is the karyotype for Trisomy 13?

A

47,XX,+13 (female)

47,XY,+13 (male)

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2
Q

What is the eponym for Trisomy 13?

A

Patau

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3
Q

What are the clinical features of Trisomy 13?

A
  • Midline deformations
  • Microcephaly
  • CHD
  • Scalp defects (cutis aplasia)
  • Holoprosencephaly
  • Microphtalmia
  • Cleft palate
  • Polydactyly
  • Renal anomalies
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4
Q

List all three trisomies in order of their incidence rates.

A

Trisomy 13: 1-2 in 10,000 (low)

Trisomy 18: 1-2 in 6,000 (medium)

Trisomy 21: 1 in 700 (high)

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5
Q

What is the prognosis for Trisomy 13?

A

Poor, 95% die in the first six months.

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6
Q

What is the karyotype for Trisomy 18?

A

47,XX,+18 (female)

47,XY,+18 (male)

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7
Q

What is the alternative name for Trisomy 18?

A

Edwards

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8
Q

What are the clinical features of Trisomy 18?

A
  • Small size
  • Small head circumference
  • Congenital heart defects
  • Overlapping fingers
  • Rocker bottom feet
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9
Q

What is the prognosis for Trisomy 18?

A

Poor, 95% die within 12 months.

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10
Q

What is the karyotype for Trisomy 21?

A

47,XX,+21 (female)

47,XY,+21 (male)

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11
Q

What is the alternative name for Trisomy 21?

A

Down

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12
Q

What are the clinical features of Trisomy 21?

A
  • Flat facial profile
  • Upslanted palpebral fissures
  • Anomalous auricles
  • Nuchal skin fold
  • Single palmar crease
  • Clinodactyly
  • Hypotonia
  • Hyperflexible joints
  • Intellectual Disability
  • Sandle gap
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13
Q

What is the prognosis for Trisomy 21?

A

Live into 50s/60s.

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14
Q

What is the karyotype of Turner Syndrome?

A

45,X

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15
Q

What are the clinical features of Turner Syndrome?

A
  • Lymphedema in infancy
  • Bicuspid aortic valve
  • Coarctation of aorta
  • Short stature
  • Gonadal regression (streak ovaries)
  • Low posterior hairline
  • Webbed neck
  • Widely spaced nipples
  • Horseshoe kidney
  • Cubitus valgus of elbow
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16
Q

What is the prognosis for Turner Syndrome?

A

Good, however the vast majority are lost as SABs. Only few live.

17
Q

What is the karyotype for Klinefelter Syndrome?

A

47,XXY

18
Q

What are the clinical features of Klinefelter Syndrome?

A
  • Tall stature
  • Long limbs
  • Learning disabilities
  • Gynecomastia (post-puberty)
  • Small testicles
  • Infertility
19
Q

What are the clinical features of 47,XXY males?

A
  • Normal physical appearance
  • Stature is above average
  • Intelligence is usually normal
  • IQ scores are often 10-15 points below that of siblings
  • Emotional immaturity and impulsive behavior
20
Q

What are the clinical features of 47,XXX females?

A
  • Physical appearance is usually normal
  • IQ is generally 10-15 points below that of siblings
  • Verbal language is often delayed
  • Women with 47,XXX karyotypes usually have normal fertility but there is an increased incidence of fertility problems compared to the normal population.
21
Q

Monosomy

A

Occurs from non-disjunction; the cell is shorted one chromosome.

22
Q

Trisomy

A

Occurs from non-disjunction; the cell gains a chromosome.

23
Q

When does heterodisomy (UPD) occur?

A

M1 block

24
Q

When does isodisomy (UPD) occur?

A

M2 block

Isaak: Genetics MBS (10 decks)

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