Trisomy 21 Flashcards

1
Q

What is Down syndrome also known as?

A

Down syndrome is also known as Trisomy 21.

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2
Q

What is the incidence of Down syndrome in live births?

A

The incidence is approximately 1:800 - 1:1000 live births.

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3
Q

How does the risk of Down syndrome correlate with maternal age?

A

The incidence is approximately 1:800 - 1:1000 live births.

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4
Q

How does the risk of Down syndrome correlate with maternal age?

A

The risk increases with increasing maternal age, with a risk of 1:400 at 35 years and 1:60 at 42 years.

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5
Q

Despite the increased risk with maternal age, who gives birth to most infants with Down syndrome?

A

Despite the increased risk with maternal age, most infants with Down syndrome are born to mothers under 30 years old.

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6
Q

What is the primary genetic mechanism responsible for Down syndrome?

A

Non-disjunction, which accounts for 95% of cases.

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7
Q

What is the percentage of Down syndrome cases caused by translocation?

A

Translocation accounts for approximately 4% of Down syndrome cases.

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8
Q

How might translocation influence the risk of Down syndrome in future pregnancies?

A

Translocation can be heritable and may influence the risk of Down syndrome in future pregnancies.

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9
Q

What is the percentage of Down syndrome cases caused by mosaicism?

A

Mosaicism accounts for about 1% of Down syndrome cases.

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10
Q

Genetics

A

Non- dysfunction
Translocation
Mosaicism

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11
Q

Clinical features most commonly found in newborn infants

A
  • Hypotonia.
  • Upslanting palpable fissures.
  • Flat nasal bridge.
  • Brachcephaly (short, wide head).
  • Short neck.
  • Protruding tongue.
  • Single palmer crease.
  • Clinodactyly (incurved fifth finger).
  • Sandle gap.
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12
Q

Cardiac complications

A

40-50% have cardiac abnormalities of which AVSD and VSD are the
most common

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13
Q

GIT complications

A

: Duodenal atresia (double bubble on AXR) is the most common.

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14
Q

Endocrine complications

A

Hypothyroidism can be present but is more common later in childhood.

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15
Q

All infants with suspected Down syndrome should have
the following

A
  • Full karyotype (unless done antenatally).
  • Thyroid test (unless cord thyroid done).
  • Cardiac evaluation (even if asymptomatic).
    Notes_on_the_newborn_infant.indd 137 2018/09/05 16:00
    138 Down Syndrome (Trisomy 21)
  • Follow-up for development, vision, hearing etc.
  • Counselling for parents.
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16
Q

Trisomy 13 (Patau) and Trisomy 18 (Edward) are the other two syndromes with an
extra chromosome, but these infants are usually born with multiple abnormalities
and seldom survive longer than a few months.

A

Trisomy 13, also known as Patau syndrome, and Trisomy 18, also known as Edwards syndrome.

17
Q

How do infants with Trisomy 13 and Trisomy 18 typically present?

A

These infants are usually born with multiple abnormalities.

18
Q

What is the typical prognosis for infants with Trisomy 13 and Trisomy 18?

A

Infants with Trisomy 13 and Trisomy 18 seldom survive longer than a few months.