Smith-Magenis Syndrome Flashcards
What is the prevalence of SMS?
1 in 25,000-15,000 live births
What are the two possible genetic bases for SMS?
- Deletion of chromosome 17 p11.2
- Mutation of gene RAI1
Describe the physical phenotype of SMS.
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
Describe the behavioural phenotype of SMS
Sleep disturbance
Challenging behaviours
Unique stereotyped behaviours: Lick and flip, self-hug
Cognitive delay
What is the average IQ?
40-50: moderate ID
What are the cognitive weaknesses and strengths of SMS?
Strengths: LTM, visual attention
Weaknesses: STM, sequential processing
What did Udwin et al. (2001) find to be lower in SMS?
Adaptive functioning: 70% adults could not dress/cook meal/do chores independently
What is delayed longer in SMS: speech or motor?
Speech: weak expressive language vs. receptive
What percentage have sleeping disturbances? Examples?
75%
Settling difficulties
Night-time waking
Daytime sleepiness
What causes excessive daytime sleepiness in SMS?
- Inverted melatonin release pattern
- disrupts circadian rhythm
- No ‘clock’ gene to control rhythm
What are the impacts of sleep disruption?
- Disruptive behaviours in day when sleepy
- Related to increased caregiver stress and parent-family problems
What kinds of medication are given to SMS?
Melatonin/beta blockers = more sleep and lowers CB
What stereotyped behaviours are common in SMS?
- teeth grinding
- insterting objects into mouth
- self-hugging
- lick and flip
What challenging behaviours are common in SMS?
- SIB
- Agression
- Temper outbursts
- attention-seeking
- Impulsivity
What is the prevalence of SIB in SMS?
67-96%
What are the unusual types of SIB seen in SMS?
Pulling out nails and inserting object into body orifices
What did Finucane et al. (2001) and Arron et al. (2011) find about SIB?
- The number of behaviours increases with age
- SMs is significant for every type of behaviour other than rubs/scratches self
What is the prevalence of aggression in SMS?
70-87%
What is unusual about attention seeking in SMS?
- Adult orientated
- Problematic for 80%
- Have special/favourite people
Describe Taylor & Oliver, 2008.
- 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
What did Wilde et al. (2013) find about attention?
SMs children are less effective at responding to cues: fail to synchronise
What is the prevalence of autism in SMS?
93%
What is not part of SMs that is on the autistic triad of impairments?
Socialisation
What is the neural correlate with impulsivity?
Atypical frontal lobe development
