Genetics and syndromes Flashcards
What is the genetic defect in Down’s syndrome?
trisomy 21
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 flat occiput protruding tongue single palmar crease sandal-toe deformity incurved 5th finger
What medical problems is down syndrome associated w ?
Hirschsprung’s disease
Duodenal atresia
CHD (VSD, PDA, AVSD)
What are medical signs found later in Down syndrome?
delayed milestones short stature low IQ Hearing impairment (secretory otitis media) visual: cataracts, squint, myopia Atlanta-axial instability risk of pneumonia ALL subfertility Alzheimers
How is Down syndrome diagnosed antenatally?
Combined test (11-13+6 weeks):
Nuchal translucency (thickened is associated w DS)
serum B-HCG
pregnancy associated plasma protein A (low indicates DS)
Then to confirm if higher risk:
• Chorionic villus sampling
• Amniocentesis
What genetic abnormality is found in Patau syndrome?
Trisomy 13
What are clinical features seen in Patau syndrome?
microcephaly exomphalos cleft lip/palate polydactyly small eyes scalp defects
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?
trisomy 18
What gender is Edward’s syndrome more common in?
females
What are some of the physical features of Edward’s syndrome?
micrognathia
low set ears
overlapping fingers
clubfoot (rocker bottom feet)
What medical problems are associated w Edward’s syndrome?
severe LD
VSD
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
hypogonadism
hypotonia
reduced IQ
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 flapping hands may not talk
What is involved in the management of angelmans?
AEDs - valproate and clonazepam
scoliosis back brace or surgery
Orthoses
SALT
What is the genetic abnormality found in fragile x syndrome?
X-linked
trinucleotide repeat expansion of CGG
What are the physical features of fragile X syndrome?
large low set ears
long thin face
high arched palate
macroorchidism
What gender if fragile X syndrome more common?
males
females mild-normal phenotype