Autosomal deletions and duplications Flashcards

1
Q

Prader WIlli

A

Chromosome 15 (q11-13) on paternal chromosome is affected (deleted or not expressed)

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2
Q

PWS incidence

A

M:F= 4:3

-1/10000-1/25000

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3
Q

PWS chromosome

A

15q11-12 paternal

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4
Q

characteristics of PWS in babies

A
  • hypotonia
  • lethargy
  • hypogonadism
  • breech
  • failure to thrive
  • sleepiness
  • triangular mouth
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5
Q

HYperphargia in PWS

A

-80%!

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6
Q

Characteristics of PWS in adults

A
  • obesity
  • hypotonia
  • infertility
  • hypogondism
  • sparse pubic hair
  • LD/borderline intellectual functioning
  • extreme flexibility
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7
Q

PWS physical appearance

A
  • prominent nasal bridge and forehead
  • small hnds and feet
  • almond shaped eyes
  • flattened face
  • thin upper lip
  • downturned mouth
  • lack of sexual development
  • striae
  • delayed motor development
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8
Q

IQ in PWS

A
  • IQ below 70 in over 90%

- autistic feautres reported in 15%

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9
Q

Angelman syndrome

A
  • deletion of 15q12 of maternal origin

- 80% due to deletion of maternally derived chromosome 15

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10
Q

Angelman

A

`15q12 deletion maternal

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11
Q

Angelman prevalence

A

-rare, 1/20,000-1/30,000

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12
Q

Features of Angelman

A
  • happy
  • paroxysmal laughter
  • hand flapping
  • clapping
  • ataxia
  • severe/profound LD
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13
Q

Facial features in Angelman

A
  • fair hair
  • blue eyes
  • microcehaly
  • flattened occiput
  • long face
  • prominent jaw
  • wide mouth
  • widely spaced teeth
  • thin upper lip
  • pointed chin
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14
Q

Epilepsy and Angelman

A
  • 90%

- EEG has highly characteristic changes as early as 3

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15
Q

Williams syndrome

A
  • rare
  • characterised by elfin appearance
  • deletion of 26 genes from the long arm of chromosome 7
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16
Q

Williams occurrence

A

-occurs in around 1/7500 and 20,000

17
Q

Presentation of Williams

A
  • irritable
  • feeding problems
  • failure to thrive
  • developmental delay
  • growth retardation
  • 60% have high calcium
  • mild to moderate LD
18
Q

Characteristic features of William’s syndrome

A
  • short stature
  • growth retardation
  • elfin face
  • hoarse voice
  • renal and CV abnormalities
  • thyroid abnormalities
  • hypercalcaemia
  • anxious, fearful. hypersensitive
  • good verbal skills
  • can be very friendly
19
Q

Cri-du-CHat

A
  • partial deletion at 5p15.2
  • 85% deletions arise spontaneously
  • majority are paternal origin
20
Q

Cri-du-chat genetics

A

-5p15.2 deletion

21
Q

Incidence of cri du chat

A

1/15,000 to 1/50000

-more common in females

22
Q

Characteristics of cri du chat

A
  • high pitched cry
  • pronounced microcephaly
  • round face with hypertelorism
  • epicanthal folds
  • slanting palpebral fissures
  • broad flat nose
  • low set ears
  • micrognathia
  • dental malocclusion
  • severe to profound LD
23
Q

Behavioural problems in Cri du CHat

A
  • seen in large amounts but may improve with age
  • self-injury, stereotypies, tantrums
  • severe-profound LD
24
Q

Smith-Magenis

A

complete or partial deletion of 17p11.2

25
Q

Smith-Magenis incidence

A

1;25,000

26
Q

LD and Smith-Magenis

A
  • 75% have mild/moderate LD

- severity of impairment correlates with the size of the 17p11 deletion

27
Q

Characteristic features of Smith Magenis

A
  • flattened mid face
  • abnormal upper lip
  • short hands and feet
  • simian crease
  • protruding tongue
  • high arched palate
  • small toes
  • hoarse deep voice
28
Q

DI George syndrome

A
  • 22q11.2 deletion

- velocardiofacial syndrome

29
Q

Di George syndrome

A
  • caused by microdeletion of chromosome 22 (22q11.2)
  • 90% cases denovo
  • 10% have ab affected parent
30
Q

Prevalence of Di George

A

1/4000

31
Q

LD in Di George

A

-over 50% have mild to moderate LD

32
Q

Heart features in Di George

A
  • tetralogy of Fallot
  • VSD
  • interrupted aortic arch
  • pulmonary atresia
33
Q

Facial features in Di George

A
  • microcephaly
  • cleft palate
  • small mouth
  • long face
  • prominent tubular nose
  • nasal speech
  • narrow palpebral fissure
  • small optic discs
34
Q

Other features in Di George

A
  • hypocalcaemia (60%)
  • seizures
  • short stature
  • hearing problems
  • renal problems
  • inguinal/umbilcal hernia
  • hypospadias
  • long thin hands
35
Q

Behavioural problems in Di George

A
  • schizophrenia-like psychosis
  • blunted affect
  • most individuals have problems with social interaction
36
Q

Rubinstein-Taybi syndrome

A
  • microdeletions in 16p12.3
  • very rare
  • 1/125,000-300,000
37
Q

Characteristics of Rubinstein-Taybi

A
  • short stature
  • moderate-severe LD
  • distinctive facial features
  • broad thumbs and first toes
  • feeding difficulties in infancy
  • congenital heart disease
  • EEG abnormalities
  • seizures
38
Q

Behavioural features in Rubinstein-Taybi

A
  • friendly disposition
  • self-stimulatory activities
  • intolerant of loud noises