Flashcards in Genetics and syndromes Deck (56):
What is the genetic defect in Down's syndrome?
mostly translocation and mosaicism
What are the clinical features of Down syndrome that can be seen at birth?
flat nasal bridge
up slanting palpebral fissures
low set small ears
single palmar crease
incurved 5th finger
What medical problems is down syndrome associated w ?
CHD (VSD, PDA, AVSD)
What are medical signs found later in Down syndrome?
Hearing impairment (secretory otitis media)
visual: cataracts, squint, myopia
risk of pneumonia
How is Down syndrome diagnosed antenatally?
Combined test (11-13+6 weeks):
Nuchal translucency (thickened is associated w DS)
pregnancy associated plasma protein A (low indicates DS)
Then to confirm if higher risk:
• Chorionic villus sampling
What genetic abnormality is found in Patau syndrome?
What are clinical features seen in Patau syndrome?
What is the prognosis of Patau syndrome?
almost all die by age 3
What ,medical problems are associated w patau?
cardiac and renal
What genetic abnormality is seen in Edward's syndrome?
What gender is Edward's syndrome more common in?
What are some of the physical features of Edward's syndrome?
low set ears
clubfoot (rocker bottom feet)
What medical problems are associated w Edward's syndrome?
What is the outlook for babies born with Edward's syndrome?
most die by the first year
half by 2m
what is the genetic abnormality seen in Prader-Willi syndrome?
lack of paternal 15q
What are some of the clinical features seen in prader-willi syndrome?
obesity - can't stop eating
What is the genetic abnormality associated w Angelman syndrome?
lack of maternal 15q
What are the clinical features of angelmans?
delayed development - severe LD
ataxic jerky movements
frequent laughter and smiling
may not talk
What is involved in the management of angelmans?
AEDs - valproate and clonazepam
scoliosis back brace or surgery
What is the genetic abnormality found in fragile x syndrome?
trinucleotide repeat expansion of CGG
What are the physical features of fragile X syndrome?
large low set ears
long thin face
high arched palate
What gender if fragile X syndrome more common?
females mild-normal phenotype
How is a diagnosis of fragile X syndrome made antenatally?
chorionic villus sampling or amniocentesis
What are the signs of and medical associations of fragile x syndrome?
hypotonia (delayed motor milestones)
autism is more common
mitral valve prolapse
What is a possible treatment of fragile x syndrome? What is it indicated for?
minocycline for. general behaviour improvement
What is the genetic abnormality found in Klinefelter's syndrome?
extra X chromosome in males
What re the clinical features of klinefelter's syndrome?
What are clinical features found in adults w klinefelters
gynaecomastia + infertility + hypogonadism + azoospermia
What are individuals w klinefelters at an increased risk of ?
increased risk of leg ulcers, osteoporosis and breast cancer
What is the treatment of klinefelter?
testosterone from puberty onwards to help development of secondary sexual characteristics and reduce long term risk of osteoporosis
What is the genetic abnormality found in Turner syndrome?
there is one X chromosome in the female
or a deletion of the short arm of one X chromosome
What are the features of Turner syndrome found in fetuses?
what are some of the features found in neonates w turner syndrome?
widely spaced nipples
short 4th metacarpal
What are some of the late signs of Turner syndrome?
ovarian defects causing infertility
wide carrying angle of arm
What is the treatment of Turner syndrome?
oestrogen - development of secondary sexual characteristics
What is the genetic anomaly in Noonan syndrome?
autosomal dominant mutation
What are the cardiac problems associated w Turner syndrome?
bicuspid aortic valve
coarctation of aorta
What are the physical features of Noonan syndrome?
flat nose bridge
What are some of the medical problems associated w Noonan syndrome?
pulmonary valve stenosis
What is the genetic abnormality associated w William's syndrome?
deletion of 26-28 genes on chromosome 7
What are the physical features of Williams syndrome?
small upturned nose
What are some of the medical conditions associated with Williams syndrome?
supravalvular aortic stenosis
mild mod LD
transient neonatal hypercalcaemia
What is muscular dystrophy?
group of inherited conditions w muscle degeneration often progressive
What is the most common muscular dystrophy?
Duchenne muscular dystrophy
What type of genetic disorder is DMD?
X linked recessive
Explain the pathophysiology behind DMD
mutations in dystrophin gene (Xp21.2)
loss of dystrophin so muscles get replaced by fibroadipose tissue
What age does DMD most commonly present?
wHat is the typical presentation of DMD?
Gower's manoeuvre - using hands to climb up legs
What abnormalities are found at birth in DMD?
what are late effects of DMD?
pseudohypertrophy of calves - unable to walk by 10-14 yrs
resp impairment and infections
orthopaedic - tendon contractures, scoliosis, osteoporosis
What are possible investigations for DMD?
increased serum creatinine kinase
muscle biopsy - abnormal fibres surrounded by fat and fibrosis tissue
Can also be diagnosed prenatally
What is the management of DMD?
1. Exercise to maintain muscle
2. Passive stretching and night splints (prevent contractors)
3. orthoses to prolong walking
4. Truncal brace, moulded sear, surgical rod for scoliosis
5. Overnight CPAP
6. Prednisolone slows decline in muscle strength
what is the median age of death of dMD>?
How does Beckers MD differ to Duchenne?
some functional dystrophin is produced so produces features like it but slower progression
what is the average age of onset of backers MD?