Genetics and Behaviour

Question 1

Describe the genetics of Down syndrome

Answer 1

Trisomy 21

Maternally derived from non-disjunction

Question 2

How can Down syndrome be diagnosed antenatally?

Answer 2

Thickened nuchal translucency
High serum bHCG
Low PAPP-A
Low unconjugated oestriol

Question 3

What are the features of Down syndrome? (appearance and organ dysfunction)

Answer 3

• 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

Question 4

What tests need to be done on a neonate with Down syndrome?

Answer 4

Red reflex (high risk cataract)
Hearing
TFTs
Ensure feeding ok (hypotonia and duodenal atresia) 
Echo

Question 5

What are the genetics of Turner syndrome?

Answer 5

45X

Question 6

What features in a newborn may point towards Turner syndrome?

Answer 6

Lymphoedema of hands and feet

Excessive skin at nape of neck

Question 7

What are the features of Turner syndrome? (appearance and organ dysfunction)

Answer 7

SHORT + AMMENORRHOEA 
\+ webbed neck
\+ wide spaced nipples
\+ down slanting palpebral fissure
\+ low set ears 

Coarctation of the aorta and bicuspid aortic valve

Question 8

What pharmacological therapy is given in Turner syndrome?

Answer 8

Growth hormone given before fusion of epiphyseal plates

Oestrogen therapy given in adolescence

Question 9

What is the inheritance pattern of DMD?

Answer 9

X-linked recessive = only males

Question 10

What investigations can aid a DMD diagnosis?

Answer 10

Creatinine kinase will be raised
Muscle biopsy
Genetic testing
Electromyography shows low frequency and amplitude

Question 11

What are the signs and symptoms of DMD?

Answer 11

• Delayed gross motor development
• Pseudohypertrophy of the calf and tongue
• Gowers sign (walks hands up legs to stand)
• Waddling or tiptoe gait

Question 12

Which muscles are affected first by DMD?

Answer 12

Proximal limb then distal limb then cardio-respiratory

Question 13

How does DMD affect the respiratory, cardiac and GI systems?

Answer 13

Respiratory:

• hypoventilation in sleep
• inability to cough/ clear infections

Cardiac:
- cardiomyopathy

GI:
- pseudo obstruction

Question 14

How is DMD managed?

Answer 14

Prednisolone can prolong ambulation for 2 years

• walking aids
• orthotics
• wheelchair
• Chest physio and tracheostomy

Question 15

What does the term “manifesting carriers” describe?

Answer 15

Females that are carriers of an X-linked disorder may get mild symptoms due to inactivation of their other X

Question 16

What is achondroplasia?

Answer 16

AD inherited condition leading to abnormal cartilage

Question 17

Describe the appearance of someone with achonodroplasia

Answer 17

• Short limbs
• Macrocephaly
• Lumbar lordosis
• Large gap between middle and ring finger

Question 18

What are the genetics of Klinefelter syndrome?

How is it treated?

Answer 18

47XXY

Testosterone injections

Question 19

What are the features of Klinefelter syndrome?

Answer 19

At puberty:

• wide hips
• gynaecomastia
• small testis
• weaker muscles

Question 20

What are the genetics of William syndrome?

Answer 20

Deleted genetic material on chromosome 7

Question 21

What are the characteristics of William syndrome?

Answer 21

• friendly, trusting personality
• star shaped pattern on iris
• small chin
• wide mouth and spaced teeth

!! SUPRAVALVULAR AORTIC STENOSIS!!
!! HYPERCALCAEMIA!!

Question 22

What are the genetics of Prader-Willi syndrome?

Answer 22

Loss of genetic material on the proximal arm of chromosome 15

Question 23

What are the characteristics of Prader-Willi syndrome?

How is it managed?

Answer 23

• constant insatiable hunger = obesity
• hypotonia
• hypogonadism

Growth hormone to help with the muscle development

Question 24

What is the inheritance pattern and features of Fragile-X?

Answer 24

X-linked

• delayed speech and language
• long face
• large ears
• large testis

Question 25

What are the features of Noonan syndrome?

Answer 25

- short - webbed neck - wide spaced eyes and nipple !!PULMONARY STENOSIS!!

Question 26

What are the genetics and characteristics of Patau syndrome?

Answer 26

Trisomy 13 - small head and eyes - cleft lip/palate - polydactyly

Question 27

What are the genetics and characteristics of Edward syndrome?

Answer 27

Trisomy 18 - low ears - small chin - rocker bottom feet - overlapping fingers

Question 28

What are the 3 core features of autism? Describe some classic features within these

Answer 28

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

Question 29

What are some differentials for autism?

Answer 29

ADHD OCD Conduct disorder Learning disability

Question 30

What conditions can autism be associated with?

Answer 30

``` Epilepsy Hearing and vision problems ADHD, depression and anxiety Pica Constipation ```

Question 31

How is autism managed?

Answer 31

Early Start Denver Model of behavioural therapy Special schooling SSRIs for repetitive stereotypes behaviour Modified environment (lights and noise) Family psychoeducation

Question 32

How is Aspreger's different from autism?

Answer 32

No impairment to language | IQ is average or above

Question 33

Define the diagnostic criteria for ADHD

Answer 33

``` Inattentive/ hyperactive behaviours + Persistent in more than 1 setting + Behaviours considered more severe than comparable individuals ```

Question 34

State some ADHD behaviours

Answer 34

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

Question 35

How is ADHD managed pharmacologically?

Answer 35

Methylphenidate

Question 36

Methylphenidate: a) baseline investigation b) Monitoring c) ADRs

Answer 36

a) ECG b) height and weight, BP, HR, appetite c) insomnia, HTN, reduced appetite, anxiety

Question 37

Define a learning disability

Answer 37

Development of the mind arrests meaning things normally learned in the developmental period are not. This leads to impairment of skills and overall intelligence

Question 38

Describe mild, moderate, severe and profound learning disabilities

Answer 38

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

Question 39

What are some causes of learning disabilities?

Answer 39

``` Hypoxia Meningitis Teratogenic drugs Autism Cerebral palsy Fragile X Prader-Wili ```

Question 40

What is conduct disorder? State some behaviours seen in children with conduct disorder

Answer 40

A severe pattern of anti-social behaviour - Aggression - Run away and skip school - Damage property - Steal