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Medical Genetics > Micro Del/Dup Syndromes > Flashcards

Micro Del/Dup Syndromes Flashcards

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1
Q

In most cases, interstitial deletions come about due to?

A

unequal crossover between homologous regions

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2
Q

What are LCR?

A

low copy repeat elements

so it is a stretch of duplicated DNA >1kb in size and shares a sequence similarity >90%

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3
Q

What causes Williams Syndrome?

A

Deletion of 7p11.23

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4
Q

What gene is mainly responsible for Williams Syndrome?

A

contiguous gene syndrome, Deletion of 7p11.23:

ELN: elastin (connective tissue protein that stores energy + resp for passive recoil)

(cousin WILLIAM is really good at ELa)

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5
Q

What are classic findings in Williams Syndrome at birth?

A

(contiguous gene syndrome, Deletion of 7p11.23; symp mainly due to ELN)

Birth:
- aortic narrowing (AKA supravalvular aortic stenosis) –> scarring process ; can lead to diverticula –> UTI + diverticulitis (in colon) ; also inc risk for peripheral pulm stenosis, hypertension, stroke
- hypercalcemia (irritable + hard to console, kidney stones, poor feeding)
(*hint = bones, stones, abdominal groans)
- facial characteristics –> “Elfin facies” course facial features

^this is like classic triad

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6
Q

Describe the facial features of Williams syndrome in more detail

A

(contiguous gene syndrome, Deletion of 7p11.23; symp mainly due to ELN)

  • so due to lack of connective tissue, develop coarse facial features and
  • periorbital puffiness/hooded eyes
  • Stellate irises (star/flare pattern)
  • Epicanthal folds
  • Medial eyebrow flare
  • Shallow nasal bridge with upturned, square or bulbous nose
  • Long, flat philtrum
  • Large (patulous) lips, especially lower
  • Wide spaced, peg shaped teeth
  • “Jowly” appearance
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7
Q

Describe other findings associated with Williams Syndrome aside from classic traid

A

(contiguous gene syndrome, Deletion of 7p11.23; symp mainly due to ELN)

  • Dev delay
  • ID (75% w IQ <70)
  • outgoing personality and want to engage in convo (“cocktail personality”)
  • increased verbal skills
  • poor visuospacial skills (like if draw house - parts are on dif parts of the page)
  • ADHD, OCD, trouble regualting emotions
  • short stature
  • low tone
  • hypothyroidism
  • trouble sleeping
  • chronic constipation
  • progressive hearing loss
  • sens to sound
  • strabismus, hyperopia
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8
Q

What is the management for Williams Syndrome for infants-toddlers?

A

(contiguous gene syndrome, Deletion of 7p11.23; symp mainly due to ELN)

  • serum Ca (sample from urine) every 4-6 mo until 2yo
  • thyroid function test annually until 3yo
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9
Q

What is the management for Williams Syndrome for all ages that take place annually?

A

(contiguous gene syndrome, Deletion of 7p11.23; symp mainly due to ELN)

  • medical eval
  • vision screening - monitor for refractive errors + stabismus
  • hearing eval
  • monitor BP in both arms
  • measure CA/creatine ratio in random spot urine & urinalysis
  • cardio eval - annually for 0-5yo, then once every 2-3 years
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10
Q

What is the management for Williams Syndrome for that take place every 2 years?

A

(contiguous gene syndrome, Deletion of 7p11.23; symp mainly due to ELN)

  • serum conc of Ca
  • thyroid function + TSH level
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11
Q

What is the management for Williams Syndrome that take place every 10 years?

A

(contiguous gene syndrome, Deletion of 7p11.23; symp mainly due to ELN)

  • renal + bladder US (looking for kidney stones + diverticulitis)
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12
Q

What is the management for Williams Syndrome for adults?

A

(contiguous gene syndrome, Deletion of 7p11.23; symp mainly due to ELN)

  • oral glucose tolerance test (OGTT) starting at 20y to eval for diab mellitus
  • eval for mitral valve prolapse, aortic insufficiency, hypertension, long QT interval, arterial stenosis
  • eval for cataracts
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13
Q

What is the cause of Smith Magenis Syndrome?

A

Deletion of 17p11.2

main effect due to RAI1 (retinoic acid-induced gene 1)

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14
Q

What are the classic findings in Smith Magenis Syndrome?

A

(Deletion of 17p11.2 – main effect due to RAI1 (retinoic acid-induced gene 1))

  • short statue
  • dev delay
  • congenital anom (heart)
  • self-injurious behavior (onychotillomania (pulling fingernails) + polyembolokoilomania (sticking things in orifices))
  • *note- they may not register pain well - so they may stick things in places or eat really hot things for sensory seeking behavior)
  • reversal of melatonin cycle
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15
Q

What are some additional findings in Smith Magenis Syndrome?

A

(Deletion of 17p11.2 – main effect due to RAI1 (retinoic acid-induced gene 1))

  • 50% have heart defects - screen w Echo
  • 20-30% have seizures - clincially observe
  • Mod ID
  • Autistic char
  • short stature (admin GH is not a for this treatment)
  • scoliosis
  • hearing, vision problems
  • renal anomalies - renal US
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16
Q

What causes Potocki-Lupski?

A

Duplication of 17p11.2

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17
Q

What 2 of these syndromes are reciprocal to one another?

A

Smith Magenis + Potocki Lupski

18
Q

What are the classic findings in Potocki Lupski?

A

(Duplication of 17p11.2)

  • even though it is a dup, it can be pretty severe
  • hypotonia + FTT
  • severe heart defects –> aortic root dilation
  • significant behavioral problems + mod ID
  • sleep disordered breathing
  • swallowing disorders
  • speech delay

note - there are cases where parents are affected, and we do not know it bc mild

19
Q

What are some facial features of Potocki Lupski?

A

(Duplication of 17p11.2)

  • this can really vary pt to pt
  • cannot always identify these as new patients
  • some may have high arched eyebrows, broad forehead, shorter philtrum
20
Q

What are management guidelines for Potocki Lupski?

A

(Duplication of 17p11.2)

  • heart anom like aortic root dilation –> Echo every 2-3y
  • scoliosis eval
  • sleep disordered breathing –> sleep study + maybe swallow study
  • PT/OT/ST as needed
  • Renal US
  • Hearing and vision eval
21
Q

What is the cause of Rubenstein Taybi?

A

Deletion of 16p13.3

CREBBP gene most important

  • 5-10% –> microdel
  • 50-70% –> CREBBP seq
  • 5-8% –> EP300 gene (that interacts w CREBBP on chr22)

(The 16yo CRaB’s BP was so high, he was RUBy red)

22
Q

What are the main physical findings with Rubenstein Taybi?

A
  • ptosis
  • prominent nose & flat philtrum
  • long columella (hangs over below the nostrils)
  • prominent chin
  • microcephaly
  • short stature
  • keloid scars
  • hypertrichosis
  • wide thumbs, radially deviated (70-97%)
  • wide first toes (87-100%)

facial findings can be subtler, but usu the fingers/toes are more noticeable

23
Q

What are some clinical features (non-physical) associated with Rubenstein Taybi?

A
  • IUGR
  • ID (IQ 25 - 79)
  • 90% language delay (they are usu non-verbal)
  • hypotonia + gross motor delay
  • MRI abnorm:
    – 74% corpus callosum
    – 63% periventricular white matter
    – 58% dysmorphic cerebellar vermis
    – 32% olfactory bulb hypoplasia
  • 24-58% heart abnorm
  • 24% hearing loss
  • feeding problems
  • kidney abnorm
  • keloid scars
  • hypertrichosis
  • immune dysfunction (72% recurrent/severe infections, 12% autoimmune)
  • neural crest derived tumors (can be all over, like neuroblastoma, oligodendroglioma, meningioma, pheochromocytoma, etc)
24
Q

What is an important management guideline to keep in mind for Rubenstein Taybi?

A
  • US in newborn in case there is tethered cord
  • no cancer or immune sys screening currently
  • and also to follow w Neuro, Growth, Opthal, Audio, Pulm, Cardio, GI, GU, Ortho, Dental
25
Q

What is the cause of Langer Giedion?

A

deletion of 8p24

26
Q

What are the two distinct syndromes of Langer Giedion?

A
  1. Trichorhinophalangeal Syndrome (Tricho: Hair; Rhino: Nose; Phalangeal: Fingers)
  2. Hereditary Multiple Osteochondromas
    - TRPSII=TRPSI+HMO
    - TRPS gene. EXT1 gene
27
Q

What are the main physical findings of Langer Giedion?

A

Trichorhinophalangeal Syndrome
- Hair –> sparse, coarse, tendency to baldness bc falls out easily
- Nose –> broad columella (“pear-shaped”), hypoplastic nostrils
- Fingers (and toes) –> brachydactyly, cone shaped epiphyses (think X-ray pic)
- short stature
- IQ usu normal or a little lower

  • bone abnorm (in fingers + elsewhere) can lead to pain, hip dysplasia, joint replacement
28
Q

What are some findings of Langer Giedion aside from TRPS?

A
  • so from the HMO (hered mult osteochondromas) –> multiple exostoses + enchondromata
  • think of it as a growth of a bone coming off another bone, and it protrudes out
  • ^ lead to disfiguration, joint limitation, some pain
  • usu not cancerous
29
Q

What are management guidelines of Langer Giedion?

A

(deletion of 8p24; TRPS gene. EXT1 gene)

  • manage symptoms –> Ortho for pain or functional issues
  • Eval for spinal stenosis as needed (looking for osteochondromas protruding into spinal canal + nerve pain)
  • Skel x-rays to eval extent of findings
30
Q

What is the cause of Miller Dieker?

A

deletion of 17p13.3

31
Q

What are the main findings of Miller Dieker + genes assocaited?

A

(deletion of 17p13.3)

  • Lissencephaly (‘smooth brain’ meaning no grooves in cortex bc not enough cortex devleoping) –> PAFAH1B1
  • Epilepsy, dysmophism, congenital abnorm (cleft palate, tethered cord) –> YWHAE &/or CRK
  • Dev level = 3-5 month old
32
Q

What are the dysmorphic features associated w Miller Dieker + genes associated?

A

(deletion of 17p13.3; lissencephaly from PAFAH1B1)

  • tall, large, square forehead
  • wrinkling forehead
  • flattened midface
  • low set posteriorly rotated ears
  • hypertelorism
  • short, upturned nose
  • prominent lateral nasal folds
33
Q

What is the management for Miller Dieker?

A

(deletion of 17p13.3)

  • Dev support
  • airway mangement
  • feeding support
  • constipation meds
  • hearing + visual screens
34
Q

What is the FISH probe to detect 22q11.2 del syndrome?

A

TUPLE1

35
Q

How common is 22q11.2 del syndrome?

A

1/1000

36
Q

What is the key gene affected in 22q11.2 del syndrome?

A

TBX1

37
Q

What percentage of 22q11.2 del syndrome is inherited?

A

10%

38
Q

What are the main findings in 22q11.2 del syndrome?

A
  • clinical constellation of findings –> all due to brachial arch derivatives
  • micrognathia
  • cleft palate
  • parathyroid hypoplasia –> low Ca levels
  • thymic aplasia –> low T-cell levels
  • cardiac defect –> TOF, interrupted aortic arch, transposition of the great arteries
  • sim to retinoic acid embryopathy
39
Q

What are 2 other names for 22q11.2 del syndrome?

A
  • DiGeorge
  • VCL - VeloCardioFacial (bc Velo = velopharyngeal insufficiency (nasal speech), Cardio = heart defect, Facial = common facial feat like cleft lip and micrognathia)
  • these were both existing terms before the del was found
40
Q

What are some additional common findings with 22q11.2 del syndrome?

A
  • dysmorphism
  • learning disabilities
  • hypernasal speech
  • hypocalcemia
  • thyroid abnormalities
  • psych disorders (schiz, anx, dep, etc.)
  • cardiovascular malformations
  • renal anomalies
  • strabismus
  • cranial nerve defects (hearing loss, facial palsy)
  • recurrent infections
  • obesity
41
Q

What are some notable outcomes with 22q11.2 del syndrome?

A
  • risk of death = 4% dep on cardiac condition
  • usu live into adults
  • immune defect usu improves, but can sometimes present as Severe Combined Immunodeficiency (SCID)
  • hypocalcemia –> can present as seizures or muscle spasms

Medical Genetics (14 decks)

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