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Flashcards in Genetics and syndromes Deck (56):
1

What is the genetic defect in Down's syndrome?

trisomy 21
mostly translocation and mosaicism

2

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

3

What medical problems is down syndrome associated w ?

Hirschsprung's disease
Duodenal atresia
CHD (VSD, PDA, AVSD)

4

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

5

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

6

What genetic abnormality is found in Patau syndrome?

Trisomy 13

7

What are clinical features seen in Patau syndrome?

microcephaly
exomphalos
cleft lip/palate
polydactyly
small eyes
scalp defects

8

What is the prognosis of Patau syndrome?

almost all die by age 3

9

What ,medical problems are associated w patau?

cardiac and renal

10

What genetic abnormality is seen in Edward's syndrome?

trisomy 18

11

What gender is Edward's syndrome more common in?

females

12

What are some of the physical features of Edward's syndrome?

micrognathia
low set ears
overlapping fingers
clubfoot (rocker bottom feet)

13

What medical problems are associated w Edward's syndrome?

severe LD
VSD

14

What is the outlook for babies born with Edward's syndrome?

most die by the first year
half by 2m

15

what is the genetic abnormality seen in Prader-Willi syndrome?

lack of paternal 15q

16

What are some of the clinical features seen in prader-willi syndrome?

obesity - can't stop eating
hypogonadism
hypotonia
reduced IQ

17

What is the genetic abnormality associated w Angelman syndrome?

lack of maternal 15q

18

What are the clinical features of angelmans?

delayed development - severe LD
ataxic jerky movements
frequent laughter and smiling
flapping hands
may not talk

19

What is involved in the management of angelmans?

AEDs - valproate and clonazepam
scoliosis back brace or surgery
Orthoses
SALT

20

What is the genetic abnormality found in fragile x syndrome?

X-linked
trinucleotide repeat expansion of CGG

21

What are the physical features of fragile X syndrome?

large low set ears
long thin face
high arched palate
macroorchidism

22

What gender if fragile X syndrome more common?

males
females mild-normal phenotype

23

How is a diagnosis of fragile X syndrome made antenatally?

chorionic villus sampling or amniocentesis

24

What are the signs of and medical associations of fragile x syndrome?

hypotonia (delayed motor milestones)
autism is more common
mitral valve prolapse
learning difficulties
behavioural problems

25

What is a possible treatment of fragile x syndrome? What is it indicated for?

minocycline for. general behaviour improvement

26

What is the genetic abnormality found in Klinefelter's syndrome?

extra X chromosome in males
47 XXY

27

What re the clinical features of klinefelter's syndrome?

clumsiness
LD

28

What are clinical features found in adults w klinefelters

tall
long limbs
gynaecomastia + infertility + hypogonadism + azoospermia

29

What are individuals w klinefelters at an increased risk of ?

increased risk of leg ulcers, osteoporosis and breast cancer

30

What is the treatment of klinefelter?

testosterone from puberty onwards to help development of secondary sexual characteristics and reduce long term risk of osteoporosis

31

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

32

What are the features of Turner syndrome found in fetuses?

generalised oedema
nuchal thickening

33

what are some of the features found in neonates w turner syndrome?

peripheral oedema
webbed neck
short stature
widely spaced nipples
short 4th metacarpal

34

What are some of the late signs of Turner syndrome?

ovarian defects causing infertility
hypothyroidism
moles
wide carrying angle of arm
delayed puberty

35

What is the treatment of Turner syndrome?

growth hormone
oestrogen - development of secondary sexual characteristics

36

What is the genetic anomaly in Noonan syndrome?

autosomal dominant mutation

37

What are the cardiac problems associated w Turner syndrome?

bicuspid aortic valve
coarctation of aorta

38

What are the physical features of Noonan syndrome?

short stature
webbed neck
flat nose bridge
pacts excavatum

39

What are some of the medical problems associated w Noonan syndrome?

pulmonary valve stenosis
ASD

40

What is the genetic abnormality associated w William's syndrome?

deletion of 26-28 genes on chromosome 7

41

What are the physical features of Williams syndrome?

short stature
small upturned nose
full lips
small chin
long philtrum
puffy eyes

42

What are some of the medical conditions associated with Williams syndrome?

supravalvular aortic stenosis
mild mod LD
transient neonatal hypercalcaemia

43

What is muscular dystrophy?

group of inherited conditions w muscle degeneration often progressive

44

What is the most common muscular dystrophy?

Duchenne muscular dystrophy

45

What type of genetic disorder is DMD?

X linked recessive

46

Explain the pathophysiology behind DMD

mutations in dystrophin gene (Xp21.2)
loss of dystrophin so muscles get replaced by fibroadipose tissue

47

What age does DMD most commonly present?

1-6yrs

48

wHat is the typical presentation of DMD?

waddling gait
Gower's manoeuvre - using hands to climb up legs

49

What abnormalities are found at birth in DMD?

none

50

what are late effects of DMD?

pseudohypertrophy of calves - unable to walk by 10-14 yrs
nocturnal hypoxia
resp impairment and infections
cardiomyopathy
orthopaedic - tendon contractures, scoliosis, osteoporosis

51

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

52

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

53

what is the median age of death of dMD>?

31

54

How does Beckers MD differ to Duchenne?

some functional dystrophin is produced so produces features like it but slower progression

55

what is the average age of onset of backers MD?

11yrs

56

What is LE of bEckers MD?

late forties to normal