Inherited Disease Flashcards

1
Q

Pathological variants of which genes are associated with breast cancer

A

BRCA1
BRCA2
TP 53 (rare)
All tumour suppressor genes

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2
Q

oncogene

A

Mutated derivative of proto-oncogene

‘Gain of function mutation’-dominant manner at cell level

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3
Q

A female with a BRCA 1 or BRCA 2 mutation is a higher risk of which cancers?

A

Breast & Ovarian

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4
Q

Which BRCA mutation gives the highest risk of Breast Cancer for females?

A

BRCA1

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5
Q

Males with which BRCA mutation are at increased risk of prostate cancer?

A

BRCA2

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6
Q

BRCA 1 2 mutations are associated with increased risk of which cancers?

A

Breast, Ovarian, Pancreatic, Prostate

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7
Q

Clinical indication of Breast cancer; you should be referred for further assessment if you have: (6 criteria)

A
  • one close relative who has had breast cancer before the age of 40
  • two or more close relatives who have had breast cancer
  • close relatives who have had breast cancer and others who have had ovarian cancer
  • one close relative who has had breast cancer in both breasts (bilateral breast cancer)
  • a male relative who has had breast cancer
  • Ashkenazi Jewish ancestry”
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8
Q

Transcription

A

DNA copied to mRNA by RNA polymerase

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9
Q

Translation

A

process in which ribosomes in the cytoplasm or ER synthesize proteins

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10
Q

Codon

A

triplet nucleotides, 64 of these encode 20 amino acids (3 exceptions)

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11
Q

Polymorphism

A

Change in triplet code results in same amino acid production
UAU to UAC = Tyr
(conservative)

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12
Q

Mutation

A

Change in triplet code results in different amino acid production
UAU to UAG = STOP
(truncating)

UAU to UUC = Phe
(non-conservative substitution)

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13
Q

Expressivity

A

Degree to which a phenotype is expressed in individuals with the same geneotype

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14
Q

MEN2

A
Autosomal dominant 
Medullary Thyroid carcinoma
Phaeochromocytoma
RET gene mutation
MEN2A represents 90%
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15
Q

MEN2

A

Autosomal dominant

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16
Q

MEN2 mutation

A

example of mutation in oncogene (gain of function)

Medullary Thyroid carcinoma, Phaeochromocytoma (benign)

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17
Q

Familial cancers involving tumour suppressor genes

A

Retinoblastoma- RB1
Li-Fraumeni syndrome (brain tumours, sarcomas, leukemia)-TP53
Familial adenomatous polyposis-APC

Breast and/or ovarian cancer-BRCA1/2

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18
Q

Colon Cancer Mutator pathway

A

Lynch Syndrome- MSH2, MLH1
<100 adenomas
High colorectal cancer risk
High endometrial cancer risk

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19
Q

Colon Cancer Suppressor pathway

A

FAP- APC gene
Classical-1000s of colonic adenomas
95% penetrant by 35
Malignancy risk ~100%

20
Q

Gardeners Syndrome

A
FAP plus
Osteomas
Soft tissue tumours:
 Sebaceous cysts
 Fibromas
 Desmoid tumours
21
Q

Germline Mutation

A

Affects all cells and can be passed on-responsible for hereditary cancers

22
Q

Somatic mutation

A

acquired genetic changes- only affects cells where mutation occurs and their direct offspring Responsible for sporadic cancer development

23
Q

Amsterdam Criteria

A

identifies families in which Lynch syndrome is likely

3 colorectal tumours
2 generations
1 diagnosed <50

24
Q

Lynch syndrome management

A

Surveillance
Chemoprophylaxis-Aspirin
Surgical prophylaxis
Family cascade management

25
Q

CHARGE Syndrome

A
Coloboma of the eye
Heart defects
Atresia of choanae
Retardation of Growth and Development
Genital and Urinary Tract abnormalities
Ear abnormalities and hearing loss
26
Q

Fetal Valporate Syndrome facial features

A
Tall forehead 
medial eyebrow deficiency
flat nasal bridge
broad nasal root
Shallow philtrum
Long upper lip
thin vermillion border
27
Q

Aneuploidy

A

An abnormal number of chromsomes

28
Q

Viable autosomal trisomies (3)

A

21(Down Syndrome)
13 (Patau syndrome)
18 (Edward syndrome)

29
Q

Only viable monosomy

A

45,X Turners syndrome

30
Q

Balanced Rearrangement

A

No loss or gain of genetic material
Reciprocal translocation, Inversion, Insertion
Requires karyotype to detect

31
Q

Unbalanced

A

Deletion
Duplication
Will be detected by microarray

32
Q

Presentation of Turners Syndrome

A

45, X – 98% conceptions end in miscarriage
75% loss of X or Y in paternal meiosis
Presents at all ages
Prenatal ↑NT or generalised oedema, hypoplastic aortic arch
Neonates neck webbing puffy hands and feet
Children short stature
Adolescents pubertal arrest, amenorrhoea

33
Q

Fluorescent In situ Hybridisation (FISH)

A

White cell culture as for G banded karyotype analysis
Metaphase spread
Uses DNA probes carrying a fluorescent label which hybridise specifically to a known chromosome region
Used to detects submicroscopic deletions
Used to detect chromosome rearrangements of relatively large DNA sequences
Requires prior knowledge of chromosome location of variant of interest
in this you glue down the chromosome and the probe is added which binds

34
Q

How is X gene expression controlled

A

XIST functional RNA expression ‘turns off’ that X chromosome and results in variation in phenotype of carriers with X linked conditions- Skewed X inactivation

35
Q

What if the XIST RNA region is methylated?

A

The XIST RNA is not expressed and that X is active

36
Q

Lyonisation

A

The activation or inactivation of X via the XIST RNA

37
Q

Paraganglioma

A

Imprinted inherited from paternal allele via dominant pattern SDHD

38
Q

Unmethylated alleles (germline)

A

Are active and expressed when inherited-imprinting

39
Q

Methylated alleles (germline)

A

Are hidden and not expressed even though person can be a carrier of a dominant condition because during oogenesis/spermatogenesis methylation and demethylation occur to match with maternally/paternally derived allele type-imprinting

40
Q

Somatic imprinting

A

Random hypermethylation of the genes
Eg Colon Cancer;of the promoter of MLH1 (inactivates it)results in mutator pathway tumour phenotype, looks like Lynch syndrome but tumours acquire the BRAF V600E driver
mutation

41
Q

Karyotype

A

Displays all of persons chromosomes and can identify the number, sex type, deletions, duplication, translocation, inversion and derivatives

42
Q

Array Comparative Genomic Hybridisation (aCGH)

A

Microarray-looking at copy number variants- doesn’t require prior knowledge of chromosomal location of variants

Glue down the probe and add in DNA(labelled with dye)
Uses competitive hybridisation between control (red) and test DNA (Green)- Yellow indicates equal amounts of both, red means there is deletion in the test, and green means there are duplication’s

43
Q

DNA sequencing

A

Single base changes to whole genome

44
Q

Downs Syndrome

A
Flat facial profile
epicanthal fold
CHD
duodenal atresia
Brushfield spots on iris
Single palmar crease
Sandal Gap
Cognitive impairment
45
Q

Penetrance

A

in genetics is the proportion of individuals carrying a particular variant (or allele) of a gene (the genotype) that also express an associated trait (the phenotype)