Paeds: Downs Syndrome

Question 1

Incidence

Answer 1

1 in 600,000 live births (incidence increases with advancing maternal age

Question 2

Cause

Answer 2

The great majority (95%) of babies aith Down syndrome have trisomy 21, usually due to non-disjunction during maternal oogenesis.
~2% are the result of a robertsonian translocation
~2% are mosaic, with a normal cell line as well as the trisomy 21 cell line

Question 3

Clinical features

Answer 3

• Usually presents at birth
• Generalized hypotonia and marked head lag
• Facial features
• Flat occiput and short neck
• Typical limb features
• Mildly short stature
• Intellectual impairments becomes apparent. IQ scores range from 25 to 70
Social skills often exceed other intellectual skills

Question 4

Facial features

Answer 4

•	Small low-set ears
•	Up slanting eyes 
•	Prominet epicanthic folds
•	A flat facial profile
•	Protruding tongue
Later brushfields spots apparent in the iris (whitish spots)

Question 5

Typical limb features

Answer 5

Short broad hands (brachydactyly), short incurved little fingers (clinodactyly), single transverse palmar crease, and a wide ‘sandal’ gap between the first and second toes.

Question 6

Associated conditions

Answer 6

• -40-50% have congenital heart disease, most commonly atrioventricular spetal defect (AVSD), ASD, VSD, Fallot tetralogy
• GI problems: duodenal atresia, anal atresia, HSD
• Increased risk of infection
• Developmental hip dysplasia
• Eczema
• Deafness: both sensorineural and conductive
• Cataracts
• Leukaemia (1%)
Acquired hypothyroidism

Question 7

Diagnosis

Answer 7

Chromosome analysis showing an additional chromosome 21 via interphase FISH

Question 8

Management Cardiac

Answer 8

Assessment

Question 9

Management

Orthopaedics

Answer 9

Hip US

Physiootherapy to improve tone and posture

Question 10

Management Audiology and opthamology

Answer 10

Audiology and ophthalmic review 1-2 years

Question 11

Management Genetic counselling

Answer 11

Not required if the cause is non-dysfunctional trisomy 21 or Mosaic trisomy 21
But this is very important if the karyotype shows a translocation

Question 12

Management

Support organisation

Answer 12

Downs Association

Question 13

Management Long term followup

Answer 13

Ideally by by a multidisciplinary team led by a paediatrician with special expertise, such as developmental paediatricin, working in a child developmental centre

Question 14

Management Haematology

Answer 14

Routine TFT annually

Question 15

Education

Answer 15

Almost all children with Down syndrome are now educated in a mainstream school with appropriate educational support

Question 16

Prognosis

Answer 16

If deaths from congenital cardiac disease are excluded, life expectancy is well in to adult life, although somewhat shortened as almost all develop Alzheimers disease by age 40 yrs
Majority of adults can live semi-independently with supervision.