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Flashcards in genetics and syndromes Deck (47)
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1
Q

genetics downs

A

trisomy 21

2
Q

features downs

A

hypotonic, flat occiput, single palmar crease, uncurved fifth finger, wide sandal gap between big and second gap

3
Q

what % have congenital heart disease in downs

A

30%

4
Q

what % downs patients live to >50

A

50%

5
Q

typical facial appearances downs

A

round face, flat nasal bridge, upslanted palpebral fissures, epicanthic folds, brushfield spots in iris, small mouth and protruding tongue, small ears, flat occiput and 3rd fontanelle

6
Q

other anomalied Downs

A

short neck, duodenal atresia, hirschsprung disease, delayed motor milestones, LD, small stature, incr susceptibility to infection, hearing, visual, incr leukaemia and tumours, incr atlanto axial instability, incr risk hypothyroid and coeliac, epilepsy, alzheimers

7
Q

what can the extra chromosome 21 be due to

A

meiotic non disjunction, translocation, mosaicism

8
Q

what is a miotic non disjunction

A

most- error at meiosis. related to maternal age. can occur in spermatogenesis. pair of chromosome 21s fail to separate so one gamete has 2 lots of chromosome 21

9
Q

if had one child with trisomy 21 due to non disjunction what is the risk of recurrence

A

1 in 200 if

10
Q

what translocation occurs in trisomy 21

A

robertsonian translocation.

11
Q

risk of recurrence downs if translocation

A

10-15% if mother is the carrier, 2.5% if father. if neither carries- risk of recurrence

12
Q

what % people carrying turners miscarry

A

> 95% end in early miscarriage

13
Q

features turners

A

lymphoedema of hands and feet in neonate, spoon shaped nails, short stature, neck webbing, wide carrying angle, widely spaced nipples, congenital heart defects, delayed puberty, ovarian dysgenesis, hypothyroid, renal anomallies, pigmented moles, recurrent otitis media

14
Q

treat turners

A

GH, oestrogen replacement

15
Q

what is mosaicism

A

non disjunction occurs during mitosis after zygote formation. some cells are normal and some arent

16
Q

does the risk of turners increase with increasing maternal age

A

no

17
Q

what is turners

A

female partly or completely missing an X chromosome

18
Q

what is PKU

A

phenylketonia. deficiency of the enzyme phenylalanine hydroxylase so get hyperphenylalanaemia

19
Q

features PKU

A

6-12m. infantile spasms, developmental delay, demyelination, decr IQ, fair heir, eczema, fits, musty urine. detected by Guthrie screening

20
Q

inheritance PKU

A

autosomal recessive

21
Q

effects of maternal PKU on the baby

A

facial dysmorphism, microcephaly, growth retardation, decr IQ

22
Q

treatment PKU

A

dietary restriction- on dietary phenyalanine.

23
Q

inheritance neurofibromatosis

A

autosomal dominant. up to 50% new mutations

24
Q

features neurofibromatosis

A

6+ cafe au lait spots, axillary freckling, firm nodular neurofibrommata palpable on peripheral nerves, Lisch nodules, bony lesions

25
Q

inheritance achondroplasia

A

autosomal dominant. 80% new mutations

26
Q

features achondroplasia

A

short stature from marked shortening of limbs, frontal bossing and large head, gross motor skills develop later. bow legs, incr lumbar lordosis

27
Q

complications achondroplasia

A

hydrocephalus, tibial bowing, joint hypermobility, foramen magnum compression, otitis media

28
Q

what happens in noonan

A

point mutation. autosomal dominant. males and females affected

29
Q

features noonan

A

wide spaced eyes, web neck, short stature, pulmonary stenosis, hypertrophic cardiomyopathy, VSD/ASD, bruising, down slanting eyes, IQ decr

30
Q

what is neurofibromatosis type 1

A

von recklinghausen, with cafe au lait etc

31
Q

what is neurofibromatosis type 2

A

bilateral acoustic neuroma and other CNS tumours

32
Q

inheritance tuberous sclerosis

A

autosomal dominant.

33
Q

features tuberous sclerosis

A

adenoma sebaceum on face, infantile spasms, LD, ashen leaf patches which fluoresce in UV light

34
Q

genetics of digeorge

A

22q11.2

35
Q

features DiGeorge

A

absent thymus, anaemia, decr GH, cleft palate, heart defects, cognitive defects

36
Q

what happens in Prader willi

A

loss of paternal - chromosome 15.

37
Q

features prader willi

A

blue eyes, blond hair, hypersomnolence. passive, autistic, introverted, unstable moods

38
Q

genetics edwards syndrome

A

trisomy 18

39
Q

features edwards syndrome

A

rockerbottom feet, rigidity with limb flexion, odd low set ears, receding chin, proptosis, cleft lip/palate, microcephaly and micrognathia

40
Q

genetics pataus syndrome

A

trisomy 13

41
Q

genetics klinefelters

A

one or more extra X chromosome. 47 XXY.

42
Q

features klinefelters

A

tall stature and long legs, small testes, gynaecomastia, LD. treat: testosterone

43
Q

features pataus

A

growth retardastion, micropthalmia, cleft lip and palate, cutis aplasia, polydactyly

44
Q

how is karyotyping done

A

FISH- fluorescent in situ hybridisation. if the piece of DNA is there (what looking for) then the probe will stick to it and flash

45
Q

what is microarray or CGH array

A

reference genomic DNA- green. test sample genomic DNA red. if same will go yellow, if patient has only one copy will be more green (losses) if patient has extra part of chromosome will be more red (gains)

46
Q

advantages microarray

A

higher pick up rate, faster, cheaper, reduces need for severl FISH tests which need to know what suspicions have to do it

47
Q

problems of microarray

A

variants of unknown significance. unexpected findings