Down's syndrome Flashcards
What is Down’s syndrome due to?
Three copies of chromosome 21
What is another term for Down’s syndrome?
Trisomy 21
What varies between individuals with Down’s syndrome?
The extent to which the person is affected and the associated conditions they have
What facial features do people with Down’s syndrome have?
- Upslanting palpebral fissures
- epicanthic folds
- Brushfield spots in iris
- protruding tongue
- small low-set ears
- round/flat face
What do people with Down’s syndrome have in their iris?
Brushfield spots
What are additional features of Down’s syndrome?
flat occiput single palmar crease Pronounced 'sandal gap' between big and first toe hypotonia congenital heart defects duodenal atresia Hirschsprung's disease
What is atlantoaxial instability?
Excessive movement at the junction between the atlas (C1) and axis (C2) as a result of either a bone or ligament abnormality
Where is the sandal gap?
Between big and first toe
What is the commonest congenital heart defect associated with Down’s syndrome?
Endocardial cushion defect
What is another term for endocardial cushion defect?
Atrioventricular septal canal defects
What are other possible cardiac defects that can occur with Down’s syndrome?
- ventricular septal defect
- secundum atrial septal defect
- tetralogy of Fallot
What cancer are people with downs more at risk of?
Acute lymphocytic leukaemia
Alzheimer’s disease
What are later complications of Down’s syndrome
learning difficulties short stature repeated respiratory infections (+hearing impairment from glue ear) hypothyroidism atlantoaxial instability
What upper respiratory tract infections are people with Down’s syndrome more at risk of?
Glue ear
How is fertility affected in people with Down’s syndrome?
- males are almost always infertile-impaired spermatogenesis
- Females are usually subfertile- problems with pregnancy
What is now the standard test for Down’s syndrome?
Combined test
When is the Combined test carried out?
Between 11 - 13+6 weeks gestation.
What is the combined test?
Ultrasound
Maternal blood test
What does the ultrasound measure?
Nuchal translucency
What is the combined blood test used to measure?
Beta‑human chorionic gonadotrophin (beta-HCG)
Pregnancy‑associated plasma protein‑A (PAPPA).
Nuchal translucency
What results from the combined test would indicate Down’s syndrome?
- High B-HCG
- Low PAPPA
- Thickened nuchal translucency
If a women booked in to get tested for Down’s syndrome later, what tests would you do?
Quadruple test
When can the quadruple test be preformed?
15-20 weeks
What does a quadruple test involve?
Testing maternal blood
What would you test the maternal blood for in a quadruple test?
- Beta-HCG
- Alpha-fetoprotein (AFP)
- Serum oestriol (female sex hormone)
- Inhibin-A.
What results from a quadruple test would indicate Down’s syndrome?
- High Beta-HCG
- Low Alpha-fetoprotein (AFP)
- Low Serum oestriol (female sex hormone)
- High inhibin-A
What do the screening tests provide?
A risk score for the fetus having Down’s syndrome.
What is classed as a high chance?
When the risk of Down’s is greater than 1 in 150
What is classed as a low chance?
When the risk of Down’s is less than 1 in 150
What is usually offered the fetus has a high chance of Down’s syndrome?
Non-invasive prenatal screening test (NIPT)
What are some routine follow up investigations that are important for children with Down’s syndrome?
- Regular thyroid checks (2 yearly)
- Echocardiogram to diagnose cardiac defects
- Regular audiometry for hearing impairment
- Regular eye checks
What is the average life expectancy for someone with Down’s syndrome?
60 years old
What would you look for in maternal blood for NIPT?
Small DNA fragments that circulate in the blood of a pregnant woman (cell free fetal DNA, cffDNA)
What is the name of the name of teh small DNA fragments that circulate in the blood of a pregnant woman?
Cell free fetal DNA, cffDNA
