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GIM Flashcards

1
Q

Analyse entire genomes across individuals, to identify genetic factors influencing response to a drug

A

Pharmacogenomics

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2
Q

Analysing an individuals genetic makeup to identify genetic factors influencing response to a drug

A

Pharmacogenetics

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3
Q

4 conditions with an X linked mode of inheritence

A

Duchenne muscular dystrophy
Fragile X syndrome
Red/green colour blindness
Haemophilia

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4
Q

3 conditions with an autosomal dominant mode of inheritence

A

Myotonic dystrophy
Marfan syndrome
Huntington’s disease

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5
Q

3 conditions with autosomal recessive mode of inheritence

A

Haemachromatosis
Sickle Cell disease
CF

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6
Q

An example of a conditions with a mitochondial mode of inheritence

A

Maternally inherited diabetes and deafness

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7
Q

2 conditions with a XL-dominant mode of inheritence

A

Rett Syndrome

Fragile X syndrome

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8
Q

3 conditions with an XL recessive mode of inheritence

A

Red/green colour blindness
Haemophilia
Duchenne muscular dystrophy

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9
Q

Describe the presentation of fragile X syndrome in males and females

A

Variable expressivity in females, fully expressive in males

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10
Q

Consanguinity increases the risk of conditions that are inherited in what way?

A

Autosomal recessive

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11
Q

3 tests you can carry out to diagnose CF

A 
Sweat test (increase in Cl- in sweat)
Molecular genetic testing
Immunoreactive trypsin (IRT) increases in CF
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12
Q

What genetic testing would you if you were suspecting chromosomal imbalance i.e. recurrent miscarriages, abnormal phenotype

A

array CGH

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13
Q

What genetic test would you use to confirm arrayCGH findings?

A

FISH or qPCR

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14
Q

What genetic test would you use to diagnose Huntingtons?

A

PCR

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15
Q

What number of CAG repeats is abnormal and results in the formation of protein aggregates in brain cells, causing progressive cell death?

A

Over 40 CAG repeats

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16
Q

How do you describe the fact that HD becomes progressively worse with each consequtive generation?

A

Anticipation

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17
Q

How would you prepare an arrayCGH test and what sized imbalances would you discard?

A

3ml blood in EDTA
1ml lithium heparin
Discard imbalances if

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18
Q

How do you describe the ‘derivative chromosome’?

A

The chromosome with the distal segment deleted

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19
Q

Sizes of 1Mb, Gb and Kb

A

1000 bases= 1Kb
1000Kb=1Mb
1000Mb=1Gb

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20
Q

What does array CGH detect?

A

Chromosomal imbalances but not balanced rearrangements

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21
Q

What genetic test is best for large translocations?

A

G banding

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22
Q

Wolf Hirshorn Syndrome

A

der(4) t4;8

Second most common recurrent chromosomal translocation

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23
Q

Mendelian

A

AD, AR, X linked and Mitochondrial inheritence patterns

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24
Q

Complex

A

Inherited but not mendelian

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25
Q

Polygenic

A

Multiple genes

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26
Q

Multifactorial

A

Multiple factors (genes and environment)

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27
Q

Sequencing 1 gene at a time

A

Sanger sequencing

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28
Q

Sequencing many genes/the entire genome at once

A

Next generation sequencing

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29
Q

A comprehensive database of human genes, genetic traits and disorders. Provides evidence about specific genes in the affected region.

A

OMIM

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30
Q

Consanguinity increases the risk of a birth defect to what? What is normal?

A

Increases to 5-6% from 2-3%

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31
Q

3 ways to determine whether a multifactorial disease has a genetic component

A

Familial clustering
Twin studies
Adoption studies

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32
Q

How do you determine whether a disease has an element of familial clustering?

A

Lambda s is the relative risk to the 2nd sibling= risk to sibling/risk to general population

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33
Q

lambda s

A

The relative risk to the 2nd sibling

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34
Q

Problems with twin studies

A

Not all monozygotic twins have equal environmental sharing in utero
Dizygotic twins can share more than 50% of their genes

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35
Q

Population Attributable Risk

A

Compare variation in human DNA sequence with disease/trait in patients and controls. Do genetic variants confer susceptibility to complex phenotypes?

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36
Q

What type of disease is associated with a genetic mutation that has a high effect but rare in the population

A

Mendelian

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37
Q

What type of disease is associated with a gene that has a less effect (additive) but common in the population?

A

Multifactorial

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38
Q

1mb regions around the mutation are identical to the common ancestor-variants near the mutation present in cases, not controls.

A

Linkage disequilibrium

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39
Q

Give 4 examples of polygenic diseases

A

Type II Diabetes
Schizophrenia
Age related macular degeneration
Alzheimer’s disease

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40
Q

DNA repair and carcinogen metabolism

A

Caretaker genes

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41
Q

Cell cycle control, programmed cell death

A

Gatekeeper genes

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42
Q

Degeneration of the macula in age related macular degeneration is characterised by early deposition of what?

A

Drusen

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43
Q

Risk factors for age related macular degeneration

A

Genetic-CFH, ARMS2

Environment-Smoking (major effect), light exposure

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44
Q

Light exposure and smoking increases the risk of age related macular degeneration by what amount?

A

70% increase in risk

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45
Q

What does the Manhatten Plot show you?

A

High case;control ratio for variant indicates increased susceptibility to disease

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46
Q

To what degree does familial clustering have an effect with regards to alzheimer’s disease?

A

Lambda s=3-10

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47
Q

Describe the genetic inheritence pattern of alzheimers

A

Early onset form is genetically heterogenous

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48
Q

In early onset alzheimer’s, there is a mutation in what gene and what are these genes normally responsible for?

A 
Presenilin 1 (PSEN1) and 2 (PSEN2)
They encode proteases with gamma secretase activity responsible for preteolytic cleavage of amyloid b A4 precursor protein
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49
Q

Describe a susceptibility allele for Alzheimers

A

A form of ApoE has a large effect on susceptibility to Alsheimers

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50
Q

Which forms of ApoE are protective or increase the susceptibility for alzheimers?

A

ApoE2-protective
ApoE3
ApoE4-Increased susceptibility (risk factor for late onset alzheimers)

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51
Q

How many ‘hits’ are required for a sporadic mutation?

A

No inherited mutation so 2 ‘hits’ required

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52
Q

Give an example of a gatekeeper gene

A

TP53

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53
Q

What type of gene control surrounding stromal environment

A

Landscapers

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54
Q

Give 4 examples of tumour suppressor genes

A

APC
BRCA1/2
TP53
Rb

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55
Q

Regulate cell growth and differentiation. Gain of function increases the risk of mutations

A

Oncogene

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56
Q

Give 2 examples of oncogenes

A

Growth and signal transduction factors

RET gene

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57
Q

Familial cancers mostly show what mode of inheritence?

A

Autosomal Dominant

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58
Q

Incorrect amino acid

A

Missense

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59
Q

Incorrect stop codon

A

Nonsense

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60
Q

Frameshift

A

Splice site, large deletions/duplications, translocation

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61
Q

Diagnostic genetic testing

A

Performed on DNA of affected relative to identify the family mutation

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62
Q

Predictive genetic testing

A

Once the mutation is identified, testing for specific mutation may be offered to other relatives

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63
Q

Rare childhood occular cancer- familial cancer

A

Retinoblastoma

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64
Q

The mutation for retinoblastoma affects what gene? Which cancers are typical in patients with retinoblastoma?

A

Rb1 gene

Retinal cancers and osteosarcoma

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65
Q

FAP accounts for what percentage of bowel cancers and what is the prognosis and preventative treatment? FAP arises from a mutation in what gene?

A

Accounts for 1% bowel cancers
100% risk bowel cancer if untreated
Colonoscopies=preventative treatment
APC tumour suppressor gene

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66
Q

HNPCC accounts for what percentage of bowel cancer? What is the prognosis?
The mutation is present in what gene?
Preventative measures?
How is it diagnosed?

A

Accounts for 2-3%
60-80% risk of bowel adenoma or cancer from mid 20s onwards.
Mismatch repair genes MLH1 (50%), MSH2 (40%), MSH6 (10%) or PMS1/2
Colonoscopy every 18-24 months from around 25 years
Diagnosed using the Amserdam Criteria of HNPCC

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67
Q

Breast/ovarian cancers arise from a mutation in which genes?

A

BRCA1/BRCA2- tumour suppressor genes

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68
Q

A mutation in BRCA1/2 increases the risk of getting breast cancer by what?

A

80% risk of breast cancer

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69
Q

A mutation in BRCA1 increases the risk of getting ovarian cancer by what?

A

40%

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70
Q

A mutation in BRCA2 increases the risk of getting ovarian cancer by what?

A

10-20%

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71
Q

LI fraumeni syndrome is a mutation in what gene?

A

p53

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72
Q

What cancers do you most commonly get if you have Li Fraumeni Syndrome?

A

Breast, sarcoma, brain etc

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73
Q

Metaphase chromosome analysis e.g. G banding

A

Conventional cytogenetics

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74
Q

Molecular resolution at all stages in the cell cycle-FISH, microarray CGH, next generation sequencing, MLPA

A

Molecular cytogenetics

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75
Q

What is more detrimental, loss or excess?

A

Loss

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76
Q

What is more detrimental, sex chromosome imbalances or autosomal imbalances

A

Autosomal imbalances

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77
Q

Trisomy or monosomy

A

Aneuploidy

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78
Q

Triploidy or tetraploidy

A

Polyploidy

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79
Q

Aneuploidy and diploidy (normal)

A

Mosaicism

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80
Q

Increasing maternal and paternal age has what effect on numberical chromosome abnormalities

A

Maternal- increase in aneuploidy

Paternal- no significant risk

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81
Q

What is the result of non dysjunction at meiosis 1?

A

2 disomic gametes, 2 nullisomic gamets

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82
Q

What is the result of non dysjunction at meiosis 2?

A

2 normal gametess, 1 nullisomic gamete, 1 disomic gamete

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83
Q

Trisomy 21 increases your risk of what conditions?

A

Leukaemia, Alzheminers, hypothyroid, obesity/coeliac, arthritis, hearing loss, seizures

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84
Q

Trisomy 18

A

Edward’s syndome

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85
Q

Trisomy 13

A

Pataum syndrome

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86
Q

Describe the features of trisomy 18

A

10% survive >1yr. Microcephaly, cleft lip and palate. Clenched hands, overlapping fingers, rockerbottom feet, severe metnal retardation, umbilical or inguinal hermia, CHD, kidney and eye problems

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87
Q

Describe the features of patau syndrome (rarest out of the 3)

A

Mental retardation, severe microcephaly, deafness, heart problems, polydactyly

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88
Q

Is there an age related risk with regards to sex chromosom aneuploidy?

A

No

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89
Q

Supermale

A

XXY

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90
Q

Superfemal

A

XXX

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91
Q

Characteristics of Turner’s syndrome

A

Infertility. Lymphatic obstruction, Short, coarctation of aorta.

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92
Q

Characteristics of Klinefelter’s syndrome

A

Infertility/hypogonadism. 80% XXY, 20% mosaic/variant. Gynacomastia (20x Increase in breast cancer), long arms and legs.

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93
Q

How does turner’s/klinefelters’ affect the persons IQ

A

Doesn’t affect it

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94
Q

What are the 3 types of triploidy

A

Digyny
Diplospermy
Dispermy

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95
Q

Digyny

A

1 egg with disomy, 1 sperm

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96
Q

Diplospermy

A

1 egg, 1 sperm with disomy

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97
Q

Dispermy

A

1 egg, 2 sperm

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98
Q

Characteristics of double paternal

A

Large placenta

Some growth delay

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99
Q

Characteristics of double maternal

A

Tiny placenta
Significant growth delay
‘head saving macrocephaly’

100
Q

Describe the way in which a molar pregnancy comes about

A

Haploid sperm+empty egg>haploid zygote>diploid zygote (‘doubling up’)>massive cystic placenta

101
Q

What is another way of describing mosaicism

A

Mitotic not dysjunction

102
Q

What is the end result of non dysjunction at 2nd mitotic division

A

25% monosmy
25% trisomy
50% normal disomy

103
Q

What does trisomic rescue mean?

A

A cell with trisomy spontaneously loses 1 chromosome to become disomy

104
Q

What are 5 consequences of mosaicism

A 
Variable phenotype, lethality
Non identical twin
Tissue specific lateral asymetry
Uniparental disomy
Recurrence risk (if gonadal)
105
Q

What are the 2 major types of chromosome change?

A

Balanced an unbalanced

106
Q

What are the 2 types of balanced chromosome rearrangements

A

Translocation and Inversion

107
Q

What are the 2 types of translocation chromosome rearrangements

A

Reciprocal

Robertsonian

108
Q

Reciprocal translocation

A

break and exchange. More common. 5-10% phenotype risk. Reproductive risk.

109
Q

Robertsonian translocation

A

Whole arm fusion of acrocentric chromosomes (13,14,15,21,22)

No phenotype/reproductive risk

110
Q

What are the 2 types of inversions

A

Pericentric and paracentric

111
Q

Pericentric inversion

A

2 breaks in differen arms of chromosome. Rotate 180 degrees then regions

112
Q

Paracentric inversion

A

(2 as i.e. the same letter) Both breaks in same half

113
Q

What is the most common cause of unbalanced chromosome rearrangements

A

Copy number variation- overall net cytogenetic gain and/or loss.

114
Q

What are the 2 main type of unbalanced chromosome rearrangements?

A

Deletions and duplications

115
Q

What are the 2 types of deletions

A

Interstitial deletion

Terminal deletion

116
Q

Segment lost in the middle of the chromosome

A

Interstitial deletion

117
Q

Segment lost at the end of the chromosome

A

Terminal deletion

118
Q

What are the 2 types of duplications?

A

Direct

Inverted

119
Q

Low copy repeats

A

Small areas of DNA with 99% homology with other sections of DNA. Results in wrong alignment during pairing in mitosis. Not completely random cause of deletion.duplications.

120
Q

Ring Chromosome

A

Breakage at both ends of the same chromosome. Terminal ends then join to make a ringed structure.

121
Q

Replication occurs during which phase of the cell cycle?

A

The S phase

122
Q

Why is DNA more stable than RNA?

A

It doesn’t have an -OH group attached to its 2nd carbon.

123
Q

What do you call the stand of DNA that acts as the template for the mRNA?

A

Antisense strand- the sense strand makes sense of the antisense strand

124
Q

How many bases are in a double stranded DNA per haploid genome?

A

3,000mb

125
Q

Which chromosome is the biggest?

A

1

126
Q

What percentage of DNA is non coding?

A

90%

127
Q

How many protein coding genes are there?

A

20,000

128
Q

Average gene size

A

50-100kb

129
Q

Average mRNA size

A

2kb

130
Q

Which part of the DNA is the coding region?

A

Exons

131
Q

Non repetitive sequences

A

Genes

132
Q

Repetitive sequences

A

Interspersed repeats e.g. Alu repeats and satellite DNA

133
Q

What parts of DNA replication occurs int he cytoplasm?

A

Translation, post-translational modification

134
Q

Alternaive splicing

A

a regulated process during gene expression that results in a single gene coding for multiple proteins.

135
Q

What are the 2 main mechanisms of alternative splicing?

A

Exon skipping

Mutually exclusive exon choice

136
Q

Exon skipping

A

Exons may be spliced together in a variety of patterns. Diversity of genome is increased due to this process.

137
Q

Mutually exclusive exon choice

A

2 exons within the same gene are put side by side as a result of exon duplication in evolution

138
Q

Describe the mechanisms by which pseudogenes arise

A

Ancestral gene>duplication>divergence>pseudogene

139
Q

A non functional gene

A

Pseudogene

140
Q

Processed genes

A

mRNA is transcibred and re-integrated into the host genome. Introless copies of genes which occasionally remain functional

141
Q

An example of a processed gene that remains functional

A

PGK2

142
Q

Give 2 exampels of repetitive DNA

A

Satellite DNA

Interspersed Repeats

143
Q

Satellite DNA

A

Large blocks at centromeres e.g. alphoid DNA

144
Q

Alphoid DNA

A

171bp repeat

145
Q

Interspersed repeats

A

Scattered around genome e.g. alu repeats.

146
Q

Alu repeats

A

500,000 copies, 3,000bps, 5% genome

147
Q

Duchenne muscular dystrophy is what type of mutation

A

Deletion

148
Q

Charcot marie tooth disease (nerve disorder) is what type of mutation?

A

Duplication

149
Q

Haemophilia A is what type of mutation

A

Gross rearrangement

150
Q

Describe the mutation in haemophilia A

A

Coded for by F8C gene- intrachromosomal recombination results in an inversion of the segment of the repeat copies
F8C gene is chopped in 2- no longer functions

151
Q

Polymorphism

A

Common silent mutation. Splice site mutations, outside exon, likely to be pathogenic

152
Q

Describe the hypermutability fo CpG dinucleotides

A

CG dinucleotides are particularly susceptible to DNA mutation;
1. methyloation of cystein
2. deamination of methylcysteine- very like thymine
3. mismatch repair proteins struggle to pick this up
Account fo 1/3rd mutation

153
Q

Mutational heterogeneity

A

Mand different mutations can cause the same disease

154
Q

Loss of function mutations are often recessive or dominant?

A

recessive

155
Q

Gain of function mutations are often recessive or dominant?

A

dominant

156
Q

An example of a gain of function mutation

A

achondroplasia-FGF-R3 gene upregulated-ngative regulator effect on bone growth

157
Q

Give 2 examples of trinucleutide repeat expansions

A 
Polyglutamine repeats (CAG)
Large, non coding repeat expansion
158
Q

Give examples of conditions that arise due to polyglutamine repeats

A

Neurodegenerative disorders e.g. Huntington’s, spinocerebellar ataxias

159
Q

Give examples of large, non coding repeat exampnsions

A

Fragile X syndrome-transcriptional silencing with CGG repeats.

160
Q

how many CGG repeats count as a full mutation in fragile X syndrome?

A

more than 200

161
Q

Congenital malformations account for what percentage of births?

A

2-3%

162
Q

Characteristics of Kabuki syndrome

A 
Learning difficulties
50% congenital heart defect
Hearing impairment
Poor growth
Cleft palate
Eversion of lateral 1/3rd eyelid
Premature breast development
Finger pads
163
Q

Characteristics of Di George syndrome

A 
Learning difficulties
75% hypocalcaemia
Seizures
Immunodeficiency
Renal malformations
Cleft palate
Velophalangeal insufficiency-sounds like you have a cold
164
Q

Characteristics of achondroplasia

A

AD
Foramen magnum compression/hydrocephalus
Rhizometric limb shortening (prox. limbs) short stature

165
Q

Characteristics of treacher collins syndorme

A

AD
Cleft palate
Hearing impairment

166
Q

Charactersitics of Waardenburg Syndrome

A 
Sensorineural hearing loss
Congenital malformations (Hirschsprung's/VSD)
Iris heterochromia
Premature greying
Areas of skin hyperpigmentation
167
Q

Characterisitsic of William’s syndrome

A

Learning difficulties ‘cocktail party’ speech
Supravalvular aortic stenosis
Peripheral pulmonary artery stenosis
Hypercalcaemia

168
Q

Characteristics of Beckworth Widermann Syndrome

A

Exomphalmos (weakness of abdominal wall surrounding umbilicus) Noenatal hypoglycaemia Increased risk of Wilm’s tumour (nephrobastoma) Large tongue, ear pits/creases, hemihypertrophy (one side of the body is larger than the other)

169
Q

Characteristics of Peutz Jegher’s syndrome

A

GI polpys

170
Q

The most common chromosomal disorder

A

Down’s syndrome

171
Q

Describe the distribution of pigmentary mosaicism

A

Pigmented patches that may follow baschko’s lines

172
Q

Give 3 examples of whole genome testing

A

G banding, next generation sequencing, microarrays

173
Q

Give 4 examples of targeted testing

A

FISH, MLPA, QF-PCR, or qPCR

174
Q

Metaphase chromosomal analysis by light microscopy e.g. G banding

A

Congentional cytogenetics

175
Q

Chromosome analysis at the molecular resolution at all stages of the cell cycle e.g. FISH, array CGH

A

Molecular Cytogenetics

176
Q

Describe the process of G banding

A

Cell culture>mitotic arrest>harvest cells>trypsin digestion>DNA stain (Giermsa or Leishman’s)

177
Q

What are 3 types of probe for FISH

A

Unique sequence
Centromere
Paints

178
Q

What type of probe is used to identify deletions/duplications?

A

Unique sequences

179
Q

What type of probe is used to identify the total no. of copie e.g. trisomy

A

Centromere

180
Q

What type of probe is used to identify translocations

A

Paints

181
Q

What is the clinical presentation of an increased copy number of CCL3LI

A

Decreased susceptibility to HIV

182
Q

What is the clinical presentation of an increased copy number of FCGR3B

A

Descreased susceptibility to inflammatory autoimmune disorders

183
Q

Currently the most importnat genome test; compares relative amounts of DNA in sample and control

A

Microarray CGH

184
Q

What does a haploinsufficiency score tell you in a microarray CGH?

A

Tells you whether an imbalance is pathogenic

185
Q

How would you prepare the blood sample for a microarray CGH?

A

3ml blood in EDTA
1-2ml Lithium heparin
Control DNA from same sex

186
Q

How do you determine regions for potential copy number changes?

A

More than 3 oligonucleotides required for any call

More than 150kb is significant

187
Q

How are the results from next generation sequencing displayed, to show dosage changes?

A

Displayed as a karyogram

188
Q

When might you use quantitative fluorescent PCR?

A

In prenatal sampling when looking for aneuploidy. Relies on differences between maternally and paternally derived alleles.

189
Q

If a mother has a balanced reciprocal translocation, how would the chromosomes pair at meiosis?

A

In a pachytene cross structure (quadrivalent)

190
Q

If reciprocally translocated chromosomes pair in a pachytene cross, what is the chance of the child inheriting unbalanced translocations?

A

50%

191
Q

give an example of a disease that arises from unbalanced separation of reciprocally translocated chromosomes at meissis

A

Wolff Hirshom syndrome (t4;11)

192
Q

When would you perform amniocentesis?

A

16 weeks

193
Q

When do you do chorionic villus sampling?

A

12 weeks

194
Q

When do you do non invasive prenatal testing?

A

12 weeks

195
Q

Nuchal thickening greater than what, increases the risk of Down’s syndrome?

A

greater than 3.5mm

196
Q

How do you calculate the combined risk for Down’s syndrome?

A

Nuchal thickening and serum screen

197
Q

What proportion of down’s syndrome foetuses sponstaneously abort post 16 weeks?

A

25%

198
Q

Primary genetic test for trisomy 21

A

Amniocentesis and chorionic villus-QfPCR

199
Q

If abnormal scan but no trisomy on QF-PCR, what geneteic test would you follow with?

A

Array CGH

200
Q

What perfecntage of chromosome abnormalities spontaneously abort?

A

50%

201
Q

What genetic test identifies bcl-abl fusion gene?

A

FISH

202
Q

What genetic test would you use to diagnose a solid tumour?

A

FISH or Gbanding

203
Q

Enables you to find genes involved, a comprehensive clinical synopsis and offers you the mode of inheritence

A

Online mendelian inheritence in man (OMIM)

204
Q

How do you carr out non disclosure testing e.g in Huntingtons?

A

Look for markers on chromosome 4 to see which alleles come from mum or dad. Allele from mum, if affected parent, has 50% chance that it carrys the mutation. Discard embryos with mother’s allele of chromosom

205
Q

What is the role of leptin>

A

It is produced by fat cells and tells the brain to
decrease food input
Increase thermogenesis
Increase physical activity

206
Q

Genetic cure for leptin deficienciency

A

Leptin replacement

207
Q

Rare, inherited AR eye disorder causing blindness at birth or infancy

A

Leber’s congenital amaurosis

208
Q

Describe the genetic abnormality in leber’s congenital amaurosis

A

RPE-retinal epithelium 65 gene is involved in teh formation of vit A, that changes retinal to retinol. Defects result in damage to the retina.

209
Q

Treatment for LCA

A

Subretinal injections; between RPE and photoreceptor, with virus containing RPE65

210
Q

Conditions for subretinal injections to treat LCA

A

Must be a missens mutation, and the patient’s must not have amblyopia (lazy eye) as this inhibits results

211
Q

Role of cytochrome p450 oxidases

A

Responsible for metabolising drugs in the liver. Also important in converting prodrugs to their active forms

212
Q

Which cytochrome p450 oxidase metabolises 25% drugs?

A

CYP2D6

213
Q

Describe the pharmacogenetics behind the administration of tamoxifen and its metabolism

A

CYP2D6 metabolises tamoxifen to its active metabolite endoxifen. Poor metaolisers due to CYP2D6 polymorphisms are associated with worse survival.

214
Q

Reproduction of only males

A

androgeneisis

215
Q

Reproduction of only females

A

Parthogeneis

216
Q

Androgenic proliferation of abnormal trophoblast tissue

A

Hydatidiform mole

217
Q

Benign ovarian teratoma-wide spectrum of tissue (epithelial, no skeletal muscles, no membrane/placenta)

A

Parthogenesis

218
Q

When are modification of the genome made that determine the sex of the genome

A

Gaemtogeneis-spermatogeneis/oogenesis

219
Q

Facial dysmorphism- protrusion of jaw, wide mouth, drooling, smiling/laughing appearance. Mental handicap-microcephaly, absent speech. Seizures and ataxia/jerky movements.

A

Angelman syndrome

220
Q

Infantile hypotonia-feeding problems, motor delay. Mental handicap. Male hypogenitalism. Hyperphagia-obesity/uncontrolled appetite.

A

Prader Willi Syndrome

221
Q

Angelman syndrome and prader willi syndrome are both associated with what genetica bnormality

A

A deletion of a part of chromosome 15.

222
Q

Specifically what genetic abnormaility would you find in Angelman syndrome

A

75% maternal chromosome deletion
1% UPD
2-5% point mutation

223
Q

Specifically what genetic abnormality would you find with prader willi syndrome?

A

Deletion of paternal chromosome 70%

UPD 2%

224
Q

COnclusion of angelman and prader willis syndrome

A

Monoallelic expression of a cluster of genes- UBE3A only expressed on maternal chromosom

225
Q

4 exampels of epigenetic modifications

A

Ubiquitination
Phosphorylation
Methylation
Acetylation

226
Q

Describe DNA methylation in imprinted genes

A

Methylating a CpG island (epigenetic modification) is carried out by DNA methyltransferases, and is reversible. Inactivates the gene. Imprinted genes show monoallelicc expression-either maternal/paternal copy is methylated and thus silenced.

227
Q

Briefly outline the foetal-maternal growth conflict

A

paternal interest-promote foetal growth

maternal interest-restrain foetal growth

228
Q

Describe the clinical presentation of beckworth weidemann syndrome

A

foetal overgrowth-organomegaly, exomphalos. Hypoglycaemia. Asymetry, tumour risk, sporadic.

229
Q

Describe the clinical presentation of russel silver syndrome

A

growth retardation in utero and postnatally- triangular face, asymetry and brain size preserved. Sporadic.

230
Q

Describe the genetic abnormailitys is beckworth weidemann syndrome and russel silver syndrome?

A

Insulin like growth factor 2- major foetal growth promotor. Usually silenced in maternal chromosome. In BWS, methylation changes activate maternal IGF2 gene. In RS, changes inactivate the IGF2 gene on the paternal chromosome

231
Q

Describe imprint switching

A

Epigenetics is reversible. Must be ‘remembered’ before somatic development and ‘forgoteten’ before gametogenesis- to erase grandparental imprint

232
Q

What makes up most of the Y chromosom?

A

heterchromatin-no definable function

233
Q

Pseudoautosomal regions

A

sections of DNA on both the X and Y chromosome

234
Q

Dosage compensation

A

Ensure functional dosage of gene on X chromosome is equal in males and females. To enable this, in females, monoallelic expression is needed, achieved by epigenetic silencing-x inactivation. Somatic cells remember silenced status. Reversed in germ cells.

235
Q

X linked recessive abnormal sweating disorder. Diagnose with starch/iodine test

A

Hypohidrotic ectodermal dysplasia

236
Q

Pharmacokinetics

A

what the body does to the drug

237
Q

Pharmacodynamics

A

what the drug does to the body

238
Q

Stratified medicine

A

Selecting therapies fo groups of patients with shared biolocal characteristics.

239
Q

Personalised medicine

A

Therapies tailored to the individual

240
Q

Describe the interaction between thiopurine methyltransferase and azathioprine

A

Asathioprine is an immunosupporessant. TPMT inactivates it to limit DNA damage. TPMT polymorphisms decrease the activity of TMPT- more DNA damage

241
Q

Describe the interation ebtween N-actelytransferase and isoniazid

A

N acetyltransferase is a group of liver enzymes which inactivate drugs. ‘fats and slow acetylators’ due to SNP variations. Slow acetylators are at increased risks of side effects from isoniazid for TB- including neuritis and liver txicity

242
Q

Describe the interaction between succinylcholine and BCHE gene

A

Succinylcholine is a muscle relaxant used in anaesthesia. BCHE gene variant inactivates it at a much slower rate-effect may therefore last for an hour or more

243
Q

Describe the interaction between aminoglycosides and mitochondrial MT-RNR1 gene.

A

Mitochondiral MT-RNR1 gene encodes mitochondrial 12srRNA. Mutations in this gene can make aminoglycoside more likely to bind to rRNA with mutation-maternal inheritence. Accounts for 30% aminoglycosdie toxicity

244
Q

Describe the interaction ebtween warfarin and CYP2C9

A

Warfarin is inactivated by CYP2D9- cytochrome p450 family, and vit k oxidoreductase complex (VKORC1) these genes explain around 60% of genetic variability of warfarin activity

245
Q

Describe the action of herceptin

A

Herceptin (Trastuzumab) targes those breast cancers with an overepression of HER2 (human epidermal growth factor receptor 2) (20% breast cancers) Trastuzumab is a monoclonal antibody to HER2

246
Q

Describe the interaction ebtween BRAF inhibitors and vemuratenib

A

50% melanomas have a mutation in the BRAF gene- vemuratenib shows better response rate to chemo

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