Genetic Conditions Flashcards
Lecture 2
What is FXS caused by?
a single gene he end of some X abnormality - narrowing at the end of one of the X chromosomes
How is FXS a neurodevelopmental difference?
it CAUSES rather than is the difference itself
How many people does FXS affect?
1/4000 males
1/5000-8000 females
What are some physical features of people with FXS?
Broad forehead
elongated face
large ears
crossed eyes (strabismus)
arched palate
hyperextensible joints
hand calluses
enlarged testicles
low muscle tone
flat feet
What is a behavioural profile of FXS?
Social avoidance & anxiety
Hyperarousal to sensory stimuli
Distractability
Irritability
High activity level
Repetitive motor behaviours
Difficulty coping with change or unpredictable events
Language problems
What are the letters of genetic code?
A T C G
What is the FMR-1 Gene made of ?
CGG, repeated (if the number of repeats is too large the gene becomes faulty)
Who will definitely have FXS?
All men with the full mutation
When do women get FXS?
Only if one copy of the X chromosone is “switched on” in each cell, so only half usually (Carriers)
What is the prevelance of DS?
1/750-1000 live births
What is the physical profile of DS?
Facial - round face, flat facial profile, small chin, almond shaped eyes, flat nasal bridge, protruding tongue due to small oral cavity and enlarged tongue.
Also, short neck, broad head, shorter arms and legs, single palm crease.
What do up to 50% of people with DS have?
Congenital heart defects common
What other physical issues could people with DS might have?
Gastroesophageal reflux.
Sleep apnoea.
Thyroid dysfunctions
What is the average life expectancy for down syndrome?
58.6
What does Collacot say about adults with down syndrome?
DS are LOWER for agression, antisocial behaviour, property destruction, disturbing others at night, scattering objects, attention seeking, self-injury, untruthfulness, excessive activity, absconding, and excessive noise THAN other learning disabilities
Predisposition to depression
What is the neurological differences in DS?
Reduced size of the brainstem and cerebellum, and global differences, such as delayed myelination and a reduction in the number of cortical granular neurons - smaller hippocampus
What is the average IQ for FXS ?
40-60 Males, females are less affected by intellectual disability
What si the average IQ for DS?
40-60 but there is room for variability
What is receptive language?
comprehension of language (receiver).Includes listening/attending to message, understanding message.Can be tested using BPVS.
What is expressive language?
Expressive language = ability to produce language (sender).Includes verbal and written language.Tested using vocabulary subscale of WAIS/WASI.
Who performs with better selective attention?
FXS < DS < control groups.
Who performs with better divided attention?
FXS = DS < control groups.
Who performs with better sustained attention?
FXS = DS = poor attenders < good attenders.
Who performs better in the walk task?
FXS < DS = poor attenders < good attenders.
Who performs better in the same-opposite task?
DS < FXS < poor attenders < good attenders.
Who performs better overall with executive function?
FXS and DS pattern similar but FXS more impaired.Probable difficulties in inhibiting previously successful response.
Cornish 2004 - Key cognitive features in FXS
Primary deficit in behavioural inhibition
Difficulties attending to/processing of complex sequential information (tendency to repeat responses rather than switch).Tangential and perseverative language.
How common is Alzheimers in DS?
DS is associated with increased risk of early onset Alzheimers Disease: by age 60 approx. 75% of those with DS will have AD (Roizen & Patterson, 2003).
