Genetics Flashcards

1
Q

How is Marfan’s inherited

A

autosomal dominant

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2
Q

Which gene is mutated in Marfan’s

A

missense mutation in chromosome 15q21
Codes for fibrillar FBN 1

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3
Q

Clinical presentation of marfan’s

A

Tall
Down slanting palpebral fissures
Aorta root dilatation and dissection
Mitral valve prolapse
spontaneous pneumothorax

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4
Q

How is CF inherited

A

Autosomal recessive disorder of exocrine gland function

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5
Q

What gene is mutated in CF

A

CFTR gene found on chromosome 7

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6
Q

Function of CFTR

A

ATP responsive chloride ion channel
Inhibits epithelium Na channels

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7
Q

How dose mutation of CFTR cause CF symptoms

A

Resp. epithelium fai to secrete Chloride ions and hyper absorbs Na ions and water -> dehydration of airway surface

surface becomes sticky
Cillia can’t work probably - bacteria grow

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8
Q

Pancreas in CF

A

Enzymes are produced but can’t be released due to defects in channels -> causing dehydration of pancreatic secretions

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9
Q

Presentation of CF in newborn

A

Positive new born screening test
meconium ileum
jaundice
pseudo-barter syndrome (hypochloremaic, hypokalaemia alkalosis)
hypoalbuniemia

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10
Q

Other presentation of CF

A

Recurrent chest infections - teenages pseudomonas
Bronchiectasis
steathorrea
faltering growth
diabetes
Nasal polyps
Distal intestinal obstruction
Infertility - 99% of males

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11
Q

Newborn screening test in relation to CF - what is raised

A

immunoreactive trypsin - raised in first 6 weeks of life with CF

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12
Q

Other Ix for CF

A

Sweat test - chloride ions >60 is diagnostic
Molecular gene testing

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13
Q

Treatment for CF

A

Chest physio - minimum twice daily
hypertonic 7% saline
long-term nebuliser ABX - colomycin / tobramycin
Proph. oral antibiotics
Creon
Calcium replacemnet

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14
Q

How many people carry CF mutation

A

one in 25

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15
Q

Galactosemia features

A

Jaundice - conjugated
Hepatomegaly
Oil-drop cataracts

Ass. coagulopathy and E.Coli sepsis in neonates

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16
Q

How Is galactosemia inherited

A

autosomal-recessive

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17
Q

What gene has a mutation in galactosemia

A

mutations and deficiency of galactose-1-phosphate uridyltransferase GALT enzyme

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18
Q

What function can’t happen in galactosemia

A

Can’t metabolise galactose or lactose

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19
Q

Management of galactoseamia

A

Lifelong diet modification
lactose and galactose free diet

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20
Q

What are Trisomy 18 (Edwards syndrome) dysmorphic features

A

Large occiput
rocker-bottom feet
Overlapping digits

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21
Q

Newborns with Trisomy 18 features

A

Micrognathia
IUGR
Hypertonia
small mouth

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22
Q

Trisomy 18 ass. features

A

cataracts
DDH
congenital heart disease - ventricular septal defects
diaphragmatic hernia
Renal abnormalities - horseshoe kidney

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23
Q

What is Tay-Sachs disease?

A

neurodegenerative lysosomal storage disorder

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24
Q

How is Tay-Sachs disease inherited?

A

autosomal-recessive disorder

More common in Ashkenzai Jewish descent - 1/250 to 1/300

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25
Q

How is CAH inherited

A

Autosomal recessive

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26
Q

What does Gilbert syndrome cause?

A

Isolated unconjugated high bilirubin
Normal LFT’s
No heamolysis

Autosomal recessive

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27
Q

What mutation is found in Gilbert’s Syndrome

A

UGT1a1 gene located on 2q37

Reductive in production of enzyme UDP-UGT which is responsible for the conjugation of bilirubin

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28
Q

What is most common cause of Prader-willi syndrome

A

deletion of paternal chromosome 15q11-q13

maternal uniparental disomy 15

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29
Q

Presentation of Prader-Willi syndrome

A

severe neonatal hypotonia
Difficulties feeding
Weight gain
Short stature - growth hormone defiency
Facial features - narrow forehead, almond shaped eyes, thin upper lip, down turned mouth
Hypogonadism
Hypothyroidism
Learning disabilities

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30
Q

What do you need to test for diagnosis of Prader-Willi syndrome

A

DNA methylation analysis

31
Q

What type of genetic mutation is in myotonic dystrophy

A

trinucleotide nuclear expansion

32
Q

What gene is involved in Retts Syndrome

A

MECP2

33
Q

How is nuerofibromatosis type 1 inherited

A

Autosomal dominant
Half are de novo mutation

34
Q

Presentation of NM1

A

Cafe au lait
Axillary / groin freckles
Lisch nodules- raised tan coloured haemartomas of the iris
ossesous lesions
hTN
Neurofibromas - more common in adolescents and adults
Cognitive impairment

35
Q

Differences between NF1 and NF2

A

NF2 never has cafe-au lait spots
axillary and groin freckles not common in nF2
Lish nodes diagnostic of NF1
Neurofibromas in NF1, NF2 swahanomas and neurilemmonas
NF2 not ass. with cognitive impairment

36
Q

How are mutations in mDNA inherited?

A

Mother inheritance

37
Q

How are mutations in nDNA inherited?

A

Follow autosomal dominant / autosomal recessive / X linked pattern

38
Q

Age of onset of mDNA mutations

A

adults

39
Q

Age of onset of nDNA mutations

A

children

40
Q

Is lactic acidosis more common to be seen in mDNA or nDNA mutations

A

mDNA

41
Q

What to primary mitochondria disorders lead to ?

A

Decrease in ATP production
Increase in reactive oxidative spieces (ROS) = leads to state of oxidative stress

Increase ROS damage mtDNA and nDNA, protein and lipid oxidation have bad affect on multiple organ systems

42
Q

What does array comparative genomic hybridisation (aCGH) look for?

A

Chromosomal copy number variations
Compares patient DNA to control DNA
Detects deletions and duplications

43
Q

What does fluorescence in situ hybridisation FISH look for?

A

Allows for targeted investigation of copy number variations and structural rearrangements

Only detects abnormalities in region targeted by chosen probe

44
Q

Trisomy 13 - Patau syndrome features

A

Closely-spaced eyes
Midline cleft lip and palate
Holoprosencephaly
Polydactyly
Cardiac abnormalities

45
Q

What mutation causes DiGeorge syndrome?

A

Deletion at 22q11 region of one copy of chromosome 22

Majority of cases De Novo
Autosomal dominant

46
Q

Name conditions that are inherited in Autosomal dominant method?

A

Myotonic dystrophy
Achondroplasia
Tuberous sclerosis
NF1
Marfans syndrome

47
Q

Name conditions that are Imprinting disorders

A

Beckwith-Wiedemann syndrome
Angelman syndrome
Prader-Wili syndrome
Albight’s hereditary oestodystropgy

48
Q

DiGeorge syndrome characteristics

A

Short stature
transient neonatal hypocalcemia
Cleft palate
Abnormalities with T cell function
TOF

49
Q

Cause of DiGeorge syndrome

A

deletion of 22q11

De Novo

50
Q

Cause of Angelman Syndrome

A

Paternal uniparental disomy of chromosome 15
Gene codes for UBE3A

Inherits both copies from Dad - none from mum

51
Q

Angelman Syndrome characteristics

A

Ataxia
Happy disposition
Wide mouth
Microcephaly

52
Q

Beckwith-Wiedemann Syndrome

A

Abnormalities at the imprinted 11p15 growth regulatory region

Paternal uniparental disomy at chromosome 11p15

53
Q

Beckwith-Wiedemann Syndrome features

A

pre- post natal overgrowth
neonatal hypoglycaemia
coarse facial features
exomphalos
earlobe creases

Increase risk of wilms tumour

54
Q

How is Lesch-Nyhan syndrome inherited

A

X-linked disorder

55
Q

Features of Lesch-nyhan syndrome

A

Gout
gross motor delay
self-mutilating behaviour

56
Q

What happens in Lesch-nyHan syndrome

A

Over production of uric acid

57
Q

Features of William’s syndrome

A

Mild microcephaly
Learning disabilities
Talkative - can usually hide degree of difficulty

58
Q

What is HLA b27 related with?

A

Reactive arthritis
Ank spondylitis

59
Q

What is HLA B47 associated with?

A

21 hydroxylase defiency

60
Q

What is HLA CW6 associated with?

A

psoriasis

61
Q

What is HLA DR2 associated with?

A

multiple sclerosis
SLE

62
Q

Criger- Najjar signs

A

severe unconjugate hyperbole

63
Q

What mutation is found in Criger-Najjar syndrome

A

mutations in UGT1A1

Leads to enzyme defect involved in converting unconjugated to conjugated

Autosomal recessive

64
Q

What is first line test for global development delay

A

microarray

65
Q

Incontinentia pigmenti

A

X-linked dominant
Linear cuteanous lesion that start blistering rash at birth - > become wart like growth and hypigmentation

66
Q

What is anticipation

A

Increase length of unstable area in gene - longer unstable area of gene, more severe and earlier disease progression

Myotonic dystrophy

67
Q

What gonadal mosaicism

A

Parents have mutation in germ cells and not in somatic cells

Achondroplasia
Osteogenesis imperfecta
Duchenne muscular dystrophy

68
Q

Fragile X - trinucleotide expansion

A

cytosine-guanine - guanine C-G-G

69
Q

Why does SMA occur

A

degeneration of alpha motor neurones in anterior spinal horn of spinal cord

deletion or mutation in SMN1 gene

Autosomal recessive

70
Q

Di George Syndrome - Catch 22

A

Cardiac
Abnormal facies
Thymic aplasia
Cleft palate
Hypocalcaemia / hypoparathyroidism

Microdeletion of 22q11.2

71
Q

Southern blotting

A

Presence of absence of specific DNA fragments in mixture of DNA

72
Q

Noonan sydnrome mutation

A

PTPN11

73
Q

Cri-du-CHat

A

High pitch scream

5p deletion

74
Q
A