Genetics and Behaviour Flashcards
Describe the genetics of Down syndrome
Trisomy 21
Maternally derived from non-disjunction
How can Down syndrome be diagnosed antenatally?
Thickened nuchal translucency
High serum bHCG
Low PAPP-A
Low unconjugated oestriol
What are the features of Down syndrome? (appearance and organ dysfunction)
- down slanting palpebral fissures
- epicanthic folds
- low set ears
- protruding tongue (not big)
- single palmar crease
- incurving little finger
- sandal gap deformity
- VSD, ASD, TOF, PDA
- duodenal atresia
- Hirschsprung
- respiratory infections
- thyroid dysfunction
- atlanto-axial instability
What tests need to be done on a neonate with Down syndrome?
Red reflex (high risk cataract) Hearing TFTs Ensure feeding ok (hypotonia and duodenal atresia) Echo
What are the genetics of Turner syndrome?
45X
What features in a newborn may point towards Turner syndrome?
Lymphoedema of hands and feet
Excessive skin at nape of neck
What are the features of Turner syndrome? (appearance and organ dysfunction)
SHORT + AMMENORRHOEA \+ webbed neck \+ wide spaced nipples \+ down slanting palpebral fissure \+ low set ears
Coarctation of the aorta and bicuspid aortic valve
What pharmacological therapy is given in Turner syndrome?
Growth hormone given before fusion of epiphyseal plates
Oestrogen therapy given in adolescence
What is the inheritance pattern of DMD?
X-linked recessive = only males
What investigations can aid a DMD diagnosis?
Creatinine kinase will be raised
Muscle biopsy
Genetic testing
Electromyography shows low frequency and amplitude
What are the signs and symptoms of DMD?
- Delayed gross motor development
- Pseudohypertrophy of the calf and tongue
- Gowers sign (walks hands up legs to stand)
- Waddling or tiptoe gait
Which muscles are affected first by DMD?
Proximal limb then distal limb then cardio-respiratory
How does DMD affect the respiratory, cardiac and GI systems?
Respiratory:
- hypoventilation in sleep
- inability to cough/ clear infections
Cardiac:
- cardiomyopathy
GI:
- pseudo obstruction
How is DMD managed?
Prednisolone can prolong ambulation for 2 years
- walking aids
- orthotics
- wheelchair
- Chest physio and tracheostomy
What does the term “manifesting carriers” describe?
Females that are carriers of an X-linked disorder may get mild symptoms due to inactivation of their other X
What is achondroplasia?
AD inherited condition leading to abnormal cartilage
Describe the appearance of someone with achonodroplasia
- Short limbs
- Macrocephaly
- Lumbar lordosis
- Large gap between middle and ring finger
What are the genetics of Klinefelter syndrome?
How is it treated?
47XXY
Testosterone injections
What are the features of Klinefelter syndrome?
At puberty:
- wide hips
- gynaecomastia
- small testis
- weaker muscles
What are the genetics of William syndrome?
Deleted genetic material on chromosome 7
What are the characteristics of William syndrome?
- friendly, trusting personality
- star shaped pattern on iris
- small chin
- wide mouth and spaced teeth
!! SUPRAVALVULAR AORTIC STENOSIS!!
!! HYPERCALCAEMIA!!
What are the genetics of Prader-Willi syndrome?
Loss of genetic material on the proximal arm of chromosome 15
What are the characteristics of Prader-Willi syndrome?
How is it managed?
- constant insatiable hunger = obesity
- hypotonia
- hypogonadism
Growth hormone to help with the muscle development
What is the inheritance pattern and features of Fragile-X?
X-linked
- delayed speech and language
- long face
- large ears
- large testis
What are the features of Noonan syndrome?
- short
- webbed neck
- wide spaced eyes and nipple
!!PULMONARY STENOSIS!!
What are the genetics and characteristics of Patau syndrome?
Trisomy 13
- small head and eyes
- cleft lip/palate
- polydactyly
What are the genetics and characteristics of Edward syndrome?
Trisomy 18
- low ears
- small chin
- rocker bottom feet
- overlapping fingers
What are the 3 core features of autism? Describe some classic features within these
Repetitive stereotyped behaviours
- fixation on an interest
- rocking and twisting
- unable to cope with change in routine
Problems with social interaction
- avoid eye contact
- unaware of social rules
- no emotional expression
Problems with communication
- echolalia
- delayed speech
What are some differentials for autism?
ADHD
OCD
Conduct disorder
Learning disability
What conditions can autism be associated with?
Epilepsy Hearing and vision problems ADHD, depression and anxiety Pica Constipation
How is autism managed?
Early Start Denver Model of behavioural therapy
Special schooling
SSRIs for repetitive stereotypes behaviour
Modified environment (lights and noise)
Family psychoeducation
How is Aspreger’s different from autism?
No impairment to language
IQ is average or above
Define the diagnostic criteria for ADHD
Inattentive/ hyperactive behaviours \+ Persistent in more than 1 setting \+ Behaviours considered more severe than comparable individuals
State some ADHD behaviours
Inattentive:
- Doesn’t finish tasks
- Poor concentration
- Poor organisation
- Forget things
Hyperactive:
- Speak over other people
- Fidgets
- Doesn’t wait their turn
- Temper tantrums and aggression
How is ADHD managed pharmacologically?
Methylphenidate
Methylphenidate:
a) baseline investigation
b) Monitoring
c) ADRs
a) ECG
b) height and weight, BP, HR, appetite
c) insomnia, HTN, reduced appetite, anxiety
Define a learning disability
Development of the mind arrests meaning things normally learned in the developmental period are not. This leads to impairment of skills and overall intelligence
Describe mild, moderate, severe and profound learning disabilities
Mild: academic difficulties but adequate language and social skills
Moderate: Communicates with limited language
Severe: Very simple communication with some motor impairment too
Profound: Severe motor and communication difficulties meaning they need help with self care
What are some causes of learning disabilities?
Hypoxia Meningitis Teratogenic drugs Autism Cerebral palsy Fragile X Prader-Wili
What is conduct disorder? State some behaviours seen in children with conduct disorder
A severe pattern of anti-social behaviour
- Aggression
- Run away and skip school
- Damage property
- Steal
