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M2M2 > Down Syndrome > Flashcards

Down Syndrome Flashcards

1
Q

Causes of Down Syndrome

95% of cases

A

Trisomy 21

i.e. parents have normal chromosomes

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2
Q

If Down Syndrome results from Trisomy 21, where the parents have normal chromosomes, what is the recurrence risk?

A

1/100 + risk of maternal age

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3
Q

What is responsible for the minority of Down Syndrome cases (3-4%)?

A

Unbalanced translocation between chromosome 21 and another acrocentric chromosome

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4
Q

Which are the acrocentric chromosomes?

A

13, 14, 15, 21, 22

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5
Q

If Down Syndrome is due to unbalanced translocation, what becomes exceedingly more important?

A

To check karyotype of parents

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6
Q

What is the least common type of Down Syndrome?

A

Mosaic Trisomy 21 (mixture of normal and cells containing 21)
1-2% patients
Phenotype tends to be more mild

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7
Q

DS
Prenatal counseling
What causes DS?
What increases risk?

A

Error of Nondysjunction

Increasing risk with maternal age

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8
Q

DS
Prenatal screening
1st trimester

A

Ultrasound measurement of nuchal folds + beta-hCG + PAPP-A
(pregnancy associated plasma protein A)

Detection rate - 82-87%

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9
Q

DS
Prenatal screening
2nd trimester

A

quad screen

  • beta-hCG
  • AFP (alpha-fetoprotein)
  • unconjugated estriol
  • inhibin level

Detection rate = 80%

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10
Q

DS prenatal screen
The 1st trimester screen usually has a 82-87% detection rate, and the 2nd trimester screen usually has an 80% detection rate; what do they have combined?

A

95%

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11
Q

If you suspect DS based on 1st or second trimester screening, how can you confirm?

A

By chromosome analysis via amniocentesis or CVS (chorionic villus sampling)

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12
Q

DS and Cell free DNA

A

Screens maternal serum for fetal cells - not perfect - false positive and false negatives associated with this screen

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13
Q

DS (Trisomy 21) is the most common chromosomal abnormality seen in liveborn infants, what is it’s estimated incidence?

A

1/700 births

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14
Q

What three kinds of trisomy may be seen in liveborn infants?

A

13, 18, 21

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15
Q

Is trisomy 21 the most common chromosomal abnormality

A

No! Not if you are being picky about the wording… it is not the most common chromosomal abnormality but it is less life threatening than abnormalities that cause pre-term death, thus it is the most common in birth

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16
Q

Features of infants with DS
Common physical features at birth

Are growth parameters abnormal?

A

No, growth parameters are usually normal

17
Q

DS physical features @ birth

ENT and Eyes

A

midfacial hypoplasia (small midface)

upslanting palpebral fissures

epicanthal folds (skin covering inner corner eyelid)

small ears

large appearing tongue (too small compartment)

18
Q

DS physical features @ birth

Muscles and appendages

A

low muscle tone, increased joint motility

short fingers, transverse palmar crease, Vth finger incurving (clinodactyly), increased space between toes 1 and 2

19
Q

DS Common Medical Issues

Cardiac Issues

A

Seen in approximately 50%

All types of anomalies may be present but AV canal is common

Echocardiogram in the newborn period is recommended

20
Q

DS Common Medical Issues
Gastrointestinal
Infants

A

10-15% of infants have structural anomalies
Esophageal atresia - esophagus end in blind ended pouch rather than connecting to stomach
Duodenal atresia - closure of a portion of the lumen of duodenum
Hirschsprungs - ganglion cells of intestine absent - inhibited paristalsis

21
Q

DS Common Medical Issues

GI in Children

A

Feeding Problems - very common
Constipation - very common
GERD - Very common
Celiac Disease - recommended screening is TTG + IgA

22
Q

DS Common Medical Issues

Ophthalmologic

A

Blocked tear ducts - can lead to conjunctivitis
myopia
lazy eye
Nystagmus
Cataracts - may present in newborn or infancy

23
Q

Nystagmus -

A

repetitive uncontrolled movements of the eye

24
Q

What ophthalmologic test is imporant for DS in infancy?

A

Light Reflex

25
Q

DS Common Medical Issues

ENT

A

Chonic ear infections
Deafness - both sensorineural and conductive
Chronic nasal congestion
Enlarged tonsils and adenoids

26
Q

Consequence of enlarge tonsils and adenoids in DS?

A

Obstructive apnea - preschool age is common time to present with this problem - also issue in older children who develop obesity

27
Q

Down Syndrome

Endocrine and Autoimmune Problems

A

Thyroid disease - most commonly hypothyroidism (1/4 but adolescence), which may be congenital or acquired

Insulin dependent diabetes

Alopecia Areata

Reduced fertility (but normal puberty)

28
Q

Can DS have babies?

A

Not males

Rare instances females

29
Q

DS Orthopedic Problems

A

Hips
Joint subluxation
Atlantoaxial subluxation

subluxation = incomplete or partial dislocation

30
Q

DS Hematologic Issues

A

Myeloproliferative disorder in the newborn (looks preleukemic)

increased risk for leukemia - 12-20x

iron deficiency anemia - usually attributable to feeding deficiencies

31
Q

DS Developmental Issues

A

Hypotonia effects gross motor development (baby walks @1 DS baby walks 2-5)

Spectrum of intellectual disability - average is mild moderate disabilities

Speech problems
- importance of sign language

32
Q

What do we mean when we say mild intellectual disability in DS?

A

Average IQ about 50

33
Q

DS Neurologic Problems

A

Hypotonia - spectrum from mild to severe

Seizures, especially infantile spasms

34
Q

DS Psychiatric issues

A

Depression
Early Alzheimer’s
Autism 1/10 patients

35
Q

DS transition to adult care issues

A

Adult providers suck (basically)

36
Q

DS and independence

A

Independence and self help skills is sometime more important than academic

Appropriate social skills can be taught

Communication skills are key to success

Patient should try to learn main disabilities / problems / medications / allergies

37
Q

DS and Genetic Research

A

“Down Syndrome Region” on chr21q
Mouse model - chromosomes 16 and 10 (similar behavior to 21 in humans)
Down syndrome and autism: why does this happen?
Increased incidence of autoimmune disorders

M2M2 (27 decks)

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