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Genetics Final > Case #5 Translocational Down Syndrome > Flashcards

Case #5 Translocational Down Syndrome Flashcards

1
Q

Patient’s mother’s History

A

Shawana Ubo mother, 23 years old

Bbay girl that was 2500 grams, 30 week gestation

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2
Q

Baby Hx

A

decreased muscle tone
low birith weight
protential for developing respiratory issues b/c baby is not full term

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3
Q

Facial features

A

nasal root, flattened maxillary and malar region

produces characteristic appearance fo trisomy 21

Facial profile is flater than normal (middle and right image)
Hands and feet are short and rounded and may have a palmar (plantar) crease.

Hypotonia is present

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4
Q

Floppy Infant Syndrome (FIS)

A

consider it as a potential Dx

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5
Q

What diseases have infant hypotonia as a symtpom (8)

A
  1. Krabbe disease
  2. Prader-Willi Syndrome
  3. Aicardi syndrome
  4. Myasthenia gravis,
  5. Kernicterus
  6. Muscular Dystrophy
    7, Rett’s Syndrome
  7. Spinal muscular atorphy
  8. Marfan’s syndrome
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6
Q

Krabbe syndrome

A

CNS disorder;
globoid cell leukodystorphy
autosomal recessive

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7
Q

Prader-Willi syndrome

A

Chromosome 15q deletion

exhibits genetic imprinting (differnt phenotype with paternal versus maternal inheritance)

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8
Q

Aicardi syndrome

A

X-chromosome mutation

ass with absence of corpus callosum

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9
Q

Myasthania Gravis

A

autoimmunie disease of NMJ

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10
Q

Kernicterus

A

Bilirubin-induced brain dysfunction

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11
Q

Muscular Dystrophy

A

X-linked damage to skeletal muscle

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12
Q

Rett’s syndrome

A

Nuerodevelopmental disorder ass. with microencephaly, small hands and feet

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13
Q

Marfan’s Syndrome

A

autosomal dominant mutation in CT with mutaiton in FBN1 which assocaites with tumor necrosis factors B-1 (TNF-Beta)

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14
Q

Spinal Muscular Atrophy

A

Collection of genetic muscle mutations both autosoal and sex-liinked
most of thema re recessive in inheritance pattern

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15
Q

Baby Barika’s symptoms

A

dysmorphic features including upslanting palpebral fissures, epicanthal folds, poor moro reflex

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16
Q

What was Barika’s cardiac exam

A

prouces holocystolic murmur

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17
Q

What were Barika’s hands lke

A

short with wtout and stubby fingers

Prominant palmar crease

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18
Q

What are signs and symptoms caused by FAS (5)

A
  1. low birth weight
  2. small head circumference
  3. fialture to thrive
  4. organ dysfunction
  5. facial abnormalities, inclduing smaller eye openings, flattened cheekbones, and indistinct philtrum (underdeveleoped groove between ose and upper lip)
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19
Q

B/c of FAS, as child maturees, may exihibit

A

epilepsy
developmental delay
poor coordination/fine otor skills
poor socialization skills, such as difficulty buidlign and maintinta freinsdhips and relatting to groups

lak of imagination or curiosity

learnng difficulties including poor memeroy, inability to understand concepts sucha s time and money, poor language comprehension, poor problem-solicng skills

behavior prolbems including hyperactiivyt, inabiltiy to concentrate, scial withdrawal, subborness, impulsiveness, asnxiety

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20
Q

What is moro relex-

A

remove body weight of baby from pad, rleease head and allow it to fall back again, normal response is for baby to have startled look, arms shoudl move sideways with palms upa nd thumbs flexed, may cry for a minute, as reflex ends,infatn draws its arms back to body with elbows flexed, then rlexases

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21
Q

Absence moro reflex on both sides uggest

A

damage to brain or spinal cord

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22
Q

Absene on only one side

A

suggests ether broken clavicle or injruty to brachial plexus

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23
Q

What is a holosystolic murmur

A

murmur heard throughout all of systole and can be ass. with a mitral valve or tricupside valve regurgition or ventricular-septal defect

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24
Q

what is a TTE

A

transthoracic echocardiography (TTE) is a protable and noninvasive and provides rapid sonogram of heart

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25
What is the clinical trial called?
Biology Study of Transient Myeloproliferative Disorder (TMD) in cChildren with Down Syndrome
26
What is the rationale of clinical trial
Studying the genes expressed in sampels of blood from patients with DS may help doctors ID biomarkers related to cancer
27
Purpose of clinical trial
to looka t blood samples from newborns with DS. Necessary to est database of ino of inants iwth gentic disorder only, cancer only, and comorbi presentation of both diseases
28
How long does genetic testing last
a couple days to proecss
29
What is incidence of Tirsomy 21
Most common autosomal disorder- 1/700-1000 live births
30
What is the majority of cases of DS caused by
nondisjuntion 47, XX, +21 47, XY, +21
31
Who was the disorder named after
John Langdon Down
32
when dd he discoer it
describedd cohort of children with mental retardation that had very similar morphological characteristics in 186 first named them mongoloids
33
WHen does trisomy 21 occur (translocation)
error or nondisjunction occurs in teh egg or sperm cell that becomes the zygote and leads to TRISOMY 21, error is at very beginning of development, every cel that comes from this zygote will hvae an extra chromosome 21
34
what is Robertsonian Translocation?
rare cause of DS, unbalanced occurs beween two ACROCENTRIC chromosomes and fusion of two long arms of each chromosome occurs with loss of short arms (not deleterious)
35
What kind of "muaiton" did Shawana have?
Balanced translocation most common between 14 and 21
36
How did Barika get DS
Mom's 14,21 + normal 21 from EACH parent (2 21s), then chidl will have DS
37
What is inheritance pattern> Chance inheriting 14,21 translocation? Chance of developing DS
Offspring has 50% chance of inheriting 14.21 translocatino from affected parent 25% chacne offpsring ris for developing DS
38
Can children be phenoyptially norma?
if mother passes along her nomral 14 if mother passes her 14,21 without passing along an additioanl chromosome 21
39
What is the mutated gene refereed to
14q21q (two q arms)
40
what is MOSAIC type of DS
nondisjucntion of 21 occurs very early in MITOTIC division AFTER FERTILIZATION so only one of the two cell lines shows a trisomy for Chromsoome 21 Therefore, peopel with DS have 2 cell lines- one with normal nmber chromosomes, and one iwth extra #21
41
How is Mosaic DS Dx?
detected by blood test at birth or during AMNIOCENTESIS or CVS duing pregnancy Typically chromosomes in 20 different cells are counted If 2+ / 20 cells are normal (have 46 chromosomes) and others have extra #21 (total of 47 chrosomeoms) , bab is said to have mosaic DS
42
What happens if mosiacism is supected
Cytogenetiist ( chromosome specialist) will suualy count extra cells to confirm Dx
43
What is a cytogenetecisst
chromosome specialist
44
How is Mosaicism described? What if there are a total of 50 cells. 10 cells are normal cell lines and 40 have extra number 21 chorosomes
The level of mosaisicm is said to be 80% or 40/50 !
45
How accurate is percentage mosaism. Are biopsies usually done
while % is usually determiend by blood cells, % may be different in other tissues or parts of the body! (i.e. 80% can actually have full trisomy in skin or brian cell) Biopsies are not usually done b/c theya re invasive and usually dont give any inof bout how a eprson with mosaic DS will ultimately funciton
46
what is the GENE-DOSAGE EFFECT of Trisomy 21 mechanims
DS pehonotype is caused by increased expression of specific genes
47
What does extra copy f proximal part of 21q.22.3 lead to
gives rise to phenotype of DS including mental retardation, facial features, hand anomalies, and cardiac defects
48
What is the "DS Critical Region"
theory that only a small protion of the chrosoome actually needed to be triplicated to get effects seen in DS not a small isolated spot, but likely several ares that are not necesarly side by side
49
HOw many genes does Chrosome 21 have
200-250 genes salles chrosome in teh body in ter so number of genes
50
GEnes that may contribute to variable pheontype in DS include
``` Superoxide Dismutase (SOD1) COL6A1 ETS2 CAF1A Cytathione BEta Synthase (CBS) DYRK CRYA1 GART IFNAR ``` APP, GLUR5, S100B, TAM, PFKL
51
Has any gene been fully linked to any feature ass iwth DS>
NO!
52
SOD1
overexpresion may cause premature again and dec fucntion of immune system role in Senile Dementia of Alzheimers type or decresed cogntion is sitll speculative
53
COL6A1
over expression may be the cause of heart defect
54
ETS2
over expression may be the cause of Sk abnormalities
55
CAF1a
overexpression may be detrimental to DNA synthesis
56
CBS (Cystathione Beta Synthase)
overexpression may disrupt metabolism and DNA repair
57
DYRK
overexpression may be cause of mental retardation
58
CRYA1
over expression may be cause of cataracts
59
GART
overexpression may be cause of cataracts
60
IFNAR
gene of expression of Interferon, over expressio may interefire with immune system as well as other organ ystems
61
what are most common cardiac defects
Endocardial Cushion defect ventricular septal defect tetralogy of allot
62
GI defects ass with DS
duodenal atresai (closure or absenec) annular pancreas Hirschpung disease
63
Long term consequence of DS
higher risk of leukemia, hypothyroiism, cervical spine instability
64
What IQ do they have?
20-35, severe 35-50 moderate 50-70 mild
65
Is there a cure of DS
no AAP.org- american acadamey of pediatrics
66
How to manage if hchld has it
screen children for cardiac defects GI defects Hearing and vision loss hypothyroidsim
67
What kind of prenatal screenign can be done?
1st trimester with combo of fetal ultrasound to meausre nuchal translucency Blood tests to measure levels of pregnancy-ass. plams protein A (PAPP-A) HCG
68
What kind of creenign can be done at 15-20 week gestation
quad screenign consisting of alpha fetal protein, estriol HCG inhibin A amniocentesis of CVS can be performed to acheive a definitieve diagnosis
69
Social implications of having DS or being a caregiver
yep

Genetics Final (8 decks)

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