Clinical genetics and dysmorphic children Flashcards Preview

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Flashcards in Clinical genetics and dysmorphic children Deck (25):
1

What % of Down syndrome is trisomy 21 and what are the others?

T21 - 95%
Translocation 3%
Mosaic 2%

2

Describe some dysmorphic features of Down syndrome

No epicanthic fold
Sandal gap toes
Simian palmar crease

3

What is trisomy 13 also called and what are the features?

13. Is patau syndrome
Microcephalic, small eyes, cleft lip/palate, polydactyly, scalp lesions,
Congenital heart/ renal.

4

What is trisomy 18 called and what are the features?

18- Edwards
Over-lapping fingers
Rocker-bottom feet
Heart/renal defects
Micrognathia
Low set ears

5

What is the karotype for turners syndrome and what are its features?

47 X0
Coarctation of the aorta
Wide nipples
Webbed neck
Infertility

6

What's the karyotype for klinefelters?

47XXY
Male, tall, female fat distribution, sterile, lower iq and speech delay

7

Which two syndromes do we see the deletion of 15q11-q13 but different outcomes?

Prader-willi (paternal)- obesity and learning difficulties
Angelman (maternal)- development delay, hyperactive, flaps hands, widely spaced teeth

This mode of inheritance is called imprinting

8

What is velocardiofacial syndrome?

Abnormal pharyngeal arch, e.g. Cleft
Cardiac abnormalities (outflow)
Deletion of 22q11.2

Shprintzen and digeorge are examples

Di George has: CATCH
C- cardiac abnormalities
A- abnormal facies
T- thymic aplasia
C- cleft palate
H- hypocalcemia/ hypoparathyriod

9

What's the carrier rate for CF gene in Caucasian population?

1/25 carrier (AR inheritance) incidence 1/2500

10

What are the important X-linked conditions to know about?

Haemophilia
Duchenne muscular dystrophy
Colour blindness
Fragile x (cgg triplet repeat)

11

What are the important AD linked genetic condictions?

Neurofibromatosis
Marfans
Huntingtons
Achondroplasia
Tuberous sclerosis

12

What can be used for rapid diagnosis of trisomy 21?

Fish - fluorescence in situ hybridisation
Prenatal and postnatal
When cells are in interphase

13

Risk of Down syndrome in a 40 year old?

1/100 (1/110)

14

What are acrocentric chromosomes? Which numbers are they?

Chromosomes where the centromere is located near one end and not in the middle.
13 14 15 21 and 22

Robersonian translocation can only happen on acrocentric chromosomes! E.g. 14:21, 21:21

15

What are the features of noonan syndrome?

Webbed neck, Pectus excavartum, short stature, pulmonary stenosis.

16

What are the features of Pierre-robin syndrome?

Cleft palate
Micrognathia
Posterior displacement of the tongue

17

What are the features of Williams syndrome?

Short stature
Learning difficulties
Friendly - extroverted - cocktail party
Transient hypercalcaemia
Supravalvular aortic stenosis

18

What Are the features of prader-Willi?

Obesity
Hypogonads
Hypotonia

19

What are the features of fragile x? What is the codon repeat?

Larning difficulties
Macrocephalic
Lond fsce
Large eArs
Macro-orchidism

CGG triplet repeats

20

What is 'anticipation' when referring to an AD inheritance?

Gets worse with each generation. More codon or nucleotide repeats.
E.g. Myotonic dystrophy

21

What gene is linked to achondroplasia and what is the inheritance pattern?

FGFR3 gene
Autosomal dominant

22

Which diseases are x-linked?

Duchene muscular dystrophy
Haemophilia
Colour blindness

23

What are the features of duchenne Muscular dystrophy?

Delayed walking, progressive weakness,
Proximal muscle weakness
Gower sign (pt 'walks' there hands up there body to go from squatting to upright)
High CK (creatinine kinases)

Gene -dystrophin gene Xp21


Starts from about 4, worsens, often can't walk by 12. Paralyses by about 20. Average Life expectancy 26.

24

Which syndrome has macrocephaly as a major characteristic?

Fragile x

25

What is potters syndrome?

Bilateral renal angenisis,
Oligohydramnious