Paeds Genetics Flashcards
what is trisomy 21 also known as
Down’s syndrome
what are the dysmorphic features of Down’s syndrome
brachycephaly (small head and flat back)
hypotonia (reduced muscle tone)
short neck
short stature
flattened face and nose
prominent epicanthic folds (folds of skin overlying medial portion of eye and eyelid)
upward sloping palpebral fissures (gaps between lower and upper eyelid)
single palmar crease
what are some complications of Down’s syndrome
learning disability
recurrent otitis media
deafness (due to recurrent glue ear and conductive hearing loss)
visual problems
hypothyroidism
cardiac defects (ASD, VSD, PDA and TOF)
atlantoaxial instability
leukaemia (especially AML)
dementia
what is the 1st line screening for Down’s syndrome
Combined test (most accurate test)
US measures nuchal translucency + maternal blood tests
result of combined test screening that suggests Down’s syndrome
Nuchal thickness >6mm
high beta-HCG levels
low pregnancy-associated plasma protein A (PAPPA)
when is 1st line screening for Down’s syndrome done
between 11 and 14 weeks
what is the triple test for Down’s syndrome
maternal bloods:
beta-HCG
alphafetoprotein
serum oestriol
when is the triple test screen done and what does it show for Down’s
14-20 weeks
high beta-HCG
low AFP
low oestriol
if screening shows increases risk, what testing is offered for Down’s
amniocentesis (done later in pregnancy)
chronic villus sampling (if earlier than 15 weeks)
what routine investigations are done for children with Down’s syndrome
Regular thyroid check (2 yearly)
echocardiogram to look for cardiac defects
regular audiometry for hearing impairment
regular eye checks
life expectancy for Down’s syndrome
60 years
what is Kleinfelter Syndrome
male has additional X chromosome
47XXY
features of Kleinfelter’s syndrome
features develop at puberty
taller height wider hips gynaecomastia weaker muscles small testicles reduced libido shyness infertility subtle learning difficulties
how is Kleinfelter’s managed
testosterone injections
IVF techniques
breast reduction surgery
what is Turner syndrome
Female has a single X chromosome
45 XO
features of Turner syndrome
short stature
webbed neck
high arching palate
downward sloping eyes with ptosis
broad chest with widely spaced nipples
cubits valgus (forearm is angles away from body)
underdeveloped ovaries
late or incomplete puberty
infertility
conditions associated with Turner syndrome
coarctation of the aorta
recurrent UTIs
recurrent otitis media
hypothyroidism
hypertension
obesity
diabetes
osteoporosis
management of Turner syndrome
growth hormone therapy - prevents short stature
oestrogen and progesterone replacement
fertility treatment
what is Marfan syndrome
autosomal dominant condition affecting fibrillin production
features of Marfan’s
tall stature long neck long limbs long fingers high arch palate hyper mobility pectus carinatum or pectus excavatum downward sloping palpebral fissures
what are the tests for achrodactyly (long fingers)
ask patient to cross thumb across palm - if it extends past the opposite edge of the palm its arachnofactyly
wrap thumb and finger around wrist - if they overlap its acrodactyly
conditions associated with Marfan’s
lens dislocation in eye joint dislocations scoliosis pneumothorax GORD mitral valve prolapse (with regurg) aortic valve prolapse (with regurg) aortic aneurysms
management
treat cardiac risk factors
physiotherapy
genetic counselling
yearly echocardiograms and ophthalmology review
what is fragile X syndrome
mutation in FMR1 gene on X chromosome
