Down Syndrome Flashcards
Define Down Syndrome
Also known as trisomy 21 - genetic condition - considerable phenotypic variation in terms of severity.
What is the relevant epidemiology of Down syndrome?
Common chromosomal disorder
Inc with maternal age - gamete non-dysjunction
Affects 1 in 800 births worldwide.
This is around 1 in 1,000 pregnancies and 1 in 336 births in the UK
What are the three main genetic underpinnings of down syndrome?
Gamete non-dysjunction (failure for chrosomes to seperate) - 95% cases, in with maternal age
Robertsonian translocation - familial
Mosiac - 1%, variable expression of phenotype
What are the key clinical features of down syndrome?
Hypotonia and hyperflexibility
Facial features - upward slatning palpebral fissures, epicanthal folds, protruding tongue, small low set ears with adherent earlobes, hypoplastic nasal bridge, small oral cavity
Single palmar crease
Short stature
Learning difficulties.
How is the ENT affected in down syndrome?
Increased suspectibility to otitis media
Obstructive sleep apnoea
Hearing loss - conductive and sensorineural
What are the affects of down syndrome on the cardiovascular system?
Congenital heart disease in 50%
VSD
Isolated secundum atrial septal defects
Tetralogy of fallot
What are the opthalmological complications of down syndrome?
Cataracts
Refractive errors
Strabismus
What endocrine disorder can be associated with down syndrome?
Thyroid disease
What gastrointestinal complications are commonly associated with Down Syndrome?
Hirschprung disease
Congenital duodenal or oesophageal atresia
Meckels diverticulum
GORD
Coeliac disease
What is the link between down syndrome and alzheimers?
Dementia commonly develops in age 30-40yrs
What are the haematologic complications in Down Syndrome?
Impaired immunity - inc suspectibility to infections
AML
Acute lymphoblastic leukemia
Transient myeloproliferative disorder (resolved by 2months)
What is the combined test for Down Syndrome?
10-14w gestation
Nuchal translucency (>3mm)
Serum free beta-hcg (raised) and serum PAPP-A (low)
What is the quadruple test for down syndrome?
14-20w gestation
Blood test - free betahCG (high), alpha fetoprotein (low), inhibin A (high) and unconjugates estriol (low)
Less accurate than the combined test
What is non-invasive prenatal testing for down syndrome?
Blood test
no risk of miscarriage
More accurate than combined or quadruple
What is the risk of down syndrome in a positive screening test?
Greater or equal to 1 in 150
What is offered to women with a positive down syndrome screening test?
CVS - between 10-14 w gestation
Amniocentesis - after 15w gestation (miscarriage risk <0.5)
How can down syndrome be diagnosed in neonates?
Chromosomal karyotype - trisomoy 21
What screening for complications do newborn with down syndrome undergo?
Echo
Radiographic swallow assessment
Red reflex - cataracts
TSH and T4 for thyroid
FBC - polycythaemia or MPD
Screening for coeliac disease
Hearing test
What health check ups and early intervention programmes exist for down syndrome?
Annual hearing checks
Annual TFTs and FBCs for thyroid disease and anaemia
Coeliac screening
Weight and height monitoring
What management may be involvement in down syndrome?
Physio and OT - fine and gross motor
SaLT
Educational support
Management of complications (cardio or gastro surgery)
What is the prognosis for Down syndrome?
Leading cause of death = infections
Congenital heart disease and early onset dementia
Median age of death is mid-50s
