Smith-Magenis Syndrome

Question 1

What is the prevalence of SMS?

Answer 1

1 in 25,000-15,000 live births

Question 2

What are the two possible genetic bases for SMS?

Answer 2

• Deletion of chromosome 17 p11.2

- Mutation of gene RAI1

Question 3

Describe the physical phenotype of SMS.

Answer 3

Facial: prominent forehead, heavy brows, broad face, upward slanting eyes, broad nasal bridge, heavy jaw, flat head
Physical: short stature, short/broad hands, hoarse/deep voice
Health: Vision and hearing problems, scoliosis, peripheral neuropathy, infantile hypotonia

Question 4

Describe the behavioural phenotype of SMS

Answer 4

Sleep disturbance
Challenging behaviours
Unique stereotyped behaviours: Lick and flip, self-hug
Cognitive delay

Question 5

What is the average IQ?

Answer 5

40-50: moderate ID

Question 6

What are the cognitive weaknesses and strengths of SMS?

Answer 6

Strengths: LTM, visual attention
Weaknesses: STM, sequential processing

Question 7

What did Udwin et al. (2001) find to be lower in SMS?

Answer 7

Adaptive functioning: 70% adults could not dress/cook meal/do chores independently

Question 8

What is delayed longer in SMS: speech or motor?

Answer 8

Speech: weak expressive language vs. receptive

Question 9

What percentage have sleeping disturbances? Examples?

Answer 9

75%
Settling difficulties
Night-time waking
Daytime sleepiness

Question 10

What causes excessive daytime sleepiness in SMS?

Answer 10

• Inverted melatonin release pattern
• disrupts circadian rhythm
• No ‘clock’ gene to control rhythm

Question 11

What are the impacts of sleep disruption?

Answer 11

• Disruptive behaviours in day when sleepy

- Related to increased caregiver stress and parent-family problems

Question 12

What kinds of medication are given to SMS?

Answer 12

Melatonin/beta blockers = more sleep and lowers CB

Question 13

What stereotyped behaviours are common in SMS?

Answer 13

• teeth grinding
• insterting objects into mouth
• self-hugging
• lick and flip

Question 14

What challenging behaviours are common in SMS?

Answer 14

• SIB
• Agression
• Temper outbursts
• attention-seeking
• Impulsivity

Question 15

What is the prevalence of SIB in SMS?

Answer 15

67-96%

Question 16

What are the unusual types of SIB seen in SMS?

Answer 16

Pulling out nails and inserting object into body orifices

Question 17

What did Finucane et al. (2001) and Arron et al. (2011) find about SIB?

Answer 17

• The number of behaviours increases with age

- SMs is significant for every type of behaviour other than rubs/scratches self

Question 18

What is the prevalence of aggression in SMS?

Answer 18

70-87%

Question 19

What is unusual about attention seeking in SMS?

Answer 19

• Adult orientated
• Problematic for 80%
• Have special/favourite people

Question 20

Describe Taylor & Oliver, 2008.

Answer 20

• Gene-environment interaction in SMS
• 5 participants, 3-13y, observed in school
• SIB and aggressive behaviour significantly associated with low adult attention
• SIB/aggression followed by increase in attention

Question 21

What did Wilde et al. (2013) find about attention?

Answer 21

SMs children are less effective at responding to cues: fail to synchronise

Question 22

What is the prevalence of autism in SMS?

Answer 22

93%

Question 23

What is not part of SMs that is on the autistic triad of impairments?

Answer 23

Socialisation

Question 24

What is the neural correlate with impulsivity?

Answer 24

Atypical frontal lobe development