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EMS - JL > 12,13,14 > Flashcards

12,13,14 Flashcards

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1
Q

What is androgenesis

A

reproduction dependent on father

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2
Q

What is pathenogenesis

A

Reproduction dependent on the mother

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3
Q

What does retention of a polar body result in

A

Parthenogenesis 46XX

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4
Q

What happens if you get an empty egg fertilised by a sperm

A

Sperm doubles up, androgenesis 46XX

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5
Q

What is a hydatidiform mole a result of

A

Androgenetic –> complete moles usually due to homozygous 46XX.
Get proliferation of abnormal trophoblast issue
May get MALIGNANT trophoblastic tumour

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6
Q

What does parthenogenesis result in

A

Benign ovarian teratomas
Derived from oocyte after their first or second meiotic division
Diploid –> varying features, mostly epithelial tissues. Lacks skeletal muscle, placenta, membranes etc.

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7
Q

Why do parthenogenic embryos die

A

Failure of development of extra embryonic structures e.g. trophoblast

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8
Q

When do androgenic embryos dei

A

At the 6 somite stage, good extra-embryonic membranes developed but poor embryo development

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9
Q

What is genetic imprinting

A

Genes imprinted with a memory of the maternal/paternal origin –> ensures functional non-equivalence of the genes

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10
Q

How is genetic imprinting encoded

A

EPIGENETIC - not in the DNA
Due to modifications during gametogenesis
Affects the expression of 100-200 genes

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11
Q

What is Angelman Syndrome

A

Maternal deletion in chromosome 15

Causes ‘puppet children’ –> facially dysmorphic (smiling/laughing), mental handicap, seizures and ataxia/jerky movement

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12
Q

Main causes of Angolan Syndroe

A

Deletion in maternal chromosome 15 (75%)
Uniparental disomy (1%) - both paternal genes
Mutation (2-5%) –> in the UBE3A gene that is only expressed on the maternal genes –> inactivated in paternal genes

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13
Q

What is Prader-Willi Syndrome

A 
Infantile hypotonia
Hyperphagia --> causes obesity
Hypogenitalism in males, cryptochidism
Small hands/feet
Mental handicap
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14
Q

Causes of Prader-WIlli syndrome

A

Deletion in paternal genes
Deletion in chromsome 15 (75%)
Uniparental disomy (25%)

UBE3A mutation in paternal gene has no effect as paternal version is inactivated anyway

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15
Q

Are DNA Methyltransferases reversible or irreversible

A

Usually reversible

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16
Q

Where does DNA methylation occur

A

At CG diculeotides - which are involved in gene regulation

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17
Q

Where do CpG islands usually occur

A

Unmethylated clusters usually in the promoters of genes allowing transcription to occur

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18
Q

What happens if there is methylation in CpG islands in gene promoter regions

A

Silences the transcription of the gene

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19
Q

Do imprinted genes show mono allelic expression

A

Yes

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20
Q

What do paternal genes drive

A

Drive foetal growth, high foetal fitness and high foetal mortality

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21
Q

What do maternal genes drive

A

Restrain foetal growth, high mortality, poor long term reproductive potential but better maternal survival rate and reproductive fitness

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22
Q

What is Beckwithh Wireman Syndrome

A

Where the paternal drive of genes wins
High birth weight, organomegaly, tumour risk, hypoglycaemia, sporadic, epigenetic abnormalities

FOETAL OVERGRWOTH

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23
Q

What is Russell - Silver Syndrome

A

Maternal drive wins –> growth retardation

Persistent post natal growth failure, triangular face, assymetry

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24
Q

What chromosome abnormalities cause BWS and RSS

A

Abnormalities in chromosome 11p15.5!

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25
What drives fetal growth
IGF2 --> normally expressed on the paternal side
26
What are the impacts of hypomethylation on chromosome 11
Decreases IGF2 --> causes RSS
27
What are the impacts of hypermethylation on chromosome 11
Increases IGF2 --> causes BWS
28
When does imprint switching occur
Must remember during somatic development Forget at gametogenesis New parental imprint is established --> essential for normal growth and development
29
What chromosome is PGK1 on
X chromosome
30
Why does X inactivation occur
Ensures male and females have equivalent doses of genes on chromosomes
31
How does X-Inactivation occur
EPIGENETIC SILENCING
32
Why is X-inactivation different to imprinting
Whole X-chromosome is silenced Random choice of chromosome silenced Occurs early in embryogenesis in the blastocyst --> get patches of cells with different X-chromsomes inactivated
33
Why do you get tortoiseshell cats
Different X-inactivation in groups of cells
34
What is hypohydriotic ectodermal dysplasia
Female carrier of X-linked mutation Due to X-inactivation get patches of skin with/without sweat glands Test with starch/iodine
35
Are females epigenetic mosaics
Yes due to patches of cells with different X's inactivated Hence female carriers of X-linked mutations such as Haemophilis and Duchennes have some functional and some abnormal cells --> consequence is variable and unpredicatable
36
What is pharamcokinetics
What the body does to a drug
37
What is pharamcodynamics
what the drug does to the body
38
what is stratified medicine
selecting therapies for groups of individuals with shared biological characteristics
39
What is personalised medicine
therapies tailored to individuals
40
Are SNPs usually functionally significant?
NO - but if proline produced causes kinks in protein which is bad
41
What is the normal response rate to cancer drugs
Approx 20% due to genetic Varaition
42
What does Thiopurine Methytransferase do? (TPMT)
Inactivates certain drugs --> mutations in it mean azothiprine (immunosuppressant) and 6-metacarptopirone and 6-thioguanine (chemo) aren't inactivated hence you get toxic products Mutation means higher drug toxicity as not inactivated
43
Whos is TPMP 3A common in
White anglo saxons.
44
Who is TMPT 3C common in
African americans
45
What are n-acetyltransferases?
Liver enzymes that deactivate drugs by acetylation Mutations mean you can get slow or fast acetylators!
46
What drugs do n-acetyltransferases inactivate
Isonizaid (for TB) Sulfasalazine (for Crohns) Hydralazine (hypertension
47
Who does fast acetylators arise in>
Nomadic populations with high meat eating diet
48
What is succinylcholine
Muscle relaxant used in anaesthesia (stops breathing) | Related to curare in poison darts
49
Mutation in what gene alters succinylcholine activity
Mutation in BCHE gene decreases bubrylcholinesterase activity This enzyme normally deactivates succinylcholine Hence mutation prolongs succinylchlines effects --> can lead to death if no ventilation
50
What does mitochondrial MT-RNR1 gene encode
Encodes mitochrondiral 12s RNA
51
What is amino glycoside induced hearing loss
G to A mutation, changes the mitochondrial rRNA structure to resemble E.Coli 165 Amino glycosides more likely to bind to this rRNA --> increases the risk of hearing loss at a younger age
52
Is amino glycoside hearing loss maternally or paternally inherited?
Maternally as it is on mitochondrial RNA
53
What mutations affect warfarin metabolism
VKORC1 and CYP2C9 mutations
54
What do 20% of breast cancer overexpress
HER-2 (Human epidermal growth factors receptor 2)
55
What can we treat HER-2 overexpression with
Trastozumav - a monoclonal antibody to HER-2
56
What mutation is seen in 50% of melanomas
``` BRAF mutation (BRAF is a serine protein kinase) Valine to glutamic acid mutation ```
57
What can we treat BRAF Mutation in melanoma with
Vemurafonib! But can have adverse effects in those without the mutation!
58
What is Huntingtons Diesease
A progressive neurogenerative disorder Affects movement Depresses mood Loss of cogntiion, function, memory loss
59
When does huntingtons generally onset
35-44
60
How is HUntingons inherited
Autosomal dominant - complete penetrance | HTT Gene on chromosome 4 --> contains a series of CAG nucleotide repeats
61
What is Huntingtons caused by
An expansion of CAG nucleotide repeats on chromosome 4
62
How many CAG nucleotide repeats is needed to cause Huntingtons
Over 40 usually
63
What does CAG encode
Glutamic Acid
64
How does CAG nucleotide repeats cause the huntingtons disease
Abnormal proteins with increased glutamic acid Form PolyQ cellular protein aggregates Basal ganglia affected especially caudate nucleus
65
Are triplet repeat disorders associated with anticipation?
Yes --> they are unstable and prone to expand
66
Which diseases in anticipation are linked to gender?
``` Huntingtons - paternal Myotonic Dystrophy (AD) - maternal Fragile X (XL recessive) - maternal means more likely to expand if you inherit it from the mmother ```
67
What is the link between CAG nucleotide repeats and age of onset
Higher number of CAG nucleotide repeats causes lower age of onset BUT applies to population as a whole but huge variation in individuals so can't predict individually
68
Do we offer testing on under 18s for Huntingtons
No - only prenatal and if positive then must have an abortion
69
What is the treatment for Huntingtons
Symptomatic treatment only No prevention or cure Testing does NOT save lives but allows people to prepare

EMS - JL (10 decks)

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