Paeds: Genetics Flashcards
what is Down’s Syndrome caused by?
trisomy 21
what are the dysmorphic features of Down’s syndrome? (8)
- hypotonia
- Brachycephaly (small head with a flat back)
- short neck
- short stature
- flattened face + nose
- prominent epicanthic folds
- upwards sloping palpable fissures
- single palmar crease
complications of Down’s syndrome (9)
- learning disability
- recurrent otitis media
- deafness: eustachian tube abnormalities –> glue ear + conductive hearing loss
- visual problems: myopia, strabismus + cataracts
- hypothyroidism
- cardiac defects: ASD, VSD, PDA, ToF
- atlantoaxial instability
- leukaemia more common
- dementia more common
3 antenatal screening tests for Down’s screening
- 1st line: Combined test
- Triple test
- Quadruple test
what is the combined test?
performed between 11-14w gestation
US + beta-HCG + PAPPA
US: Down’s if nuchal thickness >6mm
beta-HCG: higher result indicates a greater risk
Pregnancy-associated plasma protein-A: lower result indicates a greater risk
what is the triple test
performed between 14-20w gestation
Beta-HCG: higher result indicates a greater risk
Alpha-fetoprotein: lower result indicates a greater risk
Serum oestriol: lower result indicates a greater risk
what is the quadruple test?
performed between 14-20w gestation
Beta-HCG + AFP + serum oestriol + inhibin-A
inhibin-A: higher result indicates a greater risk
what is offered if the risk score for the fetus having Down’s syndrome is > 1 in 150
the woman is offered amniocentesis or chorionic villus sampling
this involves taking a sample of the fetal cells –> karyotyping
what does chorionic villus sampling involve?
an US guided biopsy of the placental tissue
done before 15w
what does amniocentesis involve?
US guided aspiration of some amniotic fluid using a needle + syringe
this is done after 15w once there is enough amniotic fluid to make it safer to take a sample
what is non-invasive prenatal testing (NIPT)?
gradually being rolled out in the NHS. Not definitive test but gives good indication of whether fetus is affected.
blood test from mother. DNA fragments analysed, some of which will come from the placental tissue and represent the fetal DNA
Mnx of Down’s
involve members of the MDT:
- occupational therapy
- speech + language
- physio
- dietician
- paediatrician
- GP
- health visitors
- cardiologist
- ENT
- audiologist
- optician
- social services
- additional support w/ education needs
- charity: Down’s Syndrome Association
name 4 routine follow up investigations that are important for children with Down’s syndrome
1) 2-yearly thyroid checks
2) echocardiogram: cardiac defects
3) audiometry
4) eye checks
what is the average life expectancy for someone with Down’s syndrome
60 years
what is Klinefelter syndrome
occurs when a male has an additional X chromosome making them 47 XXY
features of Klinefelter syndrome
males appear normal until puberty:
- taller height
- wider hips
- gynaecomastia
- weaker muscles
- small testicles
- reduced libido
- shyness
- infertility
- subtle learning difficulties (esp affecting speech + language)
mnx options for Klinefelter syndrome
- testosterone injections
- advanced IVF techniques: have the potential to allow fertility
- breast reduction surgery
MDT:
- speech + language therapy
- occupational therapy
- physiotherapy
- educational support
In Klinefelter syndrome there is a slight increased risk of? (4)
- breast cancer compared with other males
- osteoporosis
- diabetes
- anxiety + depression
What is Turner’s syndrome?
when a female has a single X chromosome making them 45XO
what are the 3 classic features in Turner’s syndrome?
- short stature
- webbed neck
- widely spaced nipples
name the features of Turner’s syndrome? (9)
- short stature
- webbed neck
- widely spaced nipples
- high arching palate
- downward sloping eyes w/ ptosis
- cubitus valgus
- underdeveloped ovaries w/ reduced function
- late or incomplete puberty
- most women are infertile
Turner’s syndrome
what is cubitus valgus
abnormal feature of the elbow
when the arm is extended downwards with the palms facing forward
the angle of the forearm at the elbow is exaggerated, angled away from the body
Turner’s syndrome
associated conditions (9)
- recurrent otitis media
- recurrent UTIs
- coarctation of the aorta
- hypothyroidism
- hypertension
- obesity
- diabetes
- osteoporosis
- various specific learning disabilities