Genetics Flashcards
Male vs female complement?
46 XY vs 46 XX
2 meanings of polymorphism?
Genetic variation with population frequency >1% or variation that does not cause disease but predisposes it
What is aneuploidy and how the body overcomes it?
Whole extra/missing chromosome and X inactivation
Robertsonian translocations are an example of + mechanism + example + what is causes?
Unbalanced translocation + a chromosome attaches to the end of another chromosome +21 becomes attached to chromosome 14 in the mother so the baby inherits 3 chromosome 21s + Down’s syndrome (trisomy 21)
Test for small chromosome segment?
PCR
First line test for unbalanced chromosome segment?
aCGH
Test for breast cancer + how it works?
HER2 FISH + DNA probe with fluorescent stain attaches to target chromosome
Central dogma?
Transcription + translation
Penetrance?
Chance you get the disease if you have the gene
Mendelian inheritance?
Disease with high penetrance passed through family lines
CD-CV hypothesis?
Common disease-causing alleles will be found in all human populations
C. = ?
Effect on base sequence
P. = ?
Effect on amino acid sequence
+2T> A?
T changes to A 2 bases into intron
Ter or * in nomenclature?
Premature stop codon
Fs in nomenclature?
Frameshift
Trisomy 21?
Down’s syndrome
Trisomy 18?
Edwards syndrome
Maternal deletion on chromosome 15?
Angelman syndrome
Paternal deletion on chromosome 15?
Prader-Willi syndrome
Turner’s syndrome complement?
45 X
Klinefelter’s syndrome complement?
47 XXY
Key point about genetic testing with aCGH?
Only detects imbalance/ does not detect rearrangements
Explain mosaicism?
Cells in the body having different small mutations in them
Test for looking at the whole set of chromosomes?
Karyotyping
Test for sequencing a whole genome + advantage + diasadvanatge?
NGS + cheap + any detected abnormality could be disease causing OR just a polymorphism
How the disadvantage of NGS is overcome?
Filtering - excludes if known polymorphism
Chromosome that is affected by deletions that causes DiGeorge syndrome?
22
Disease with 100% penetrance?
Huntington’s disease
Why is every copy of the genome different?
Crossing over during meiosis
What disease is Philadelphia chromosome 22 seen in + treatment?
Leukaemia + tyrosine kinase inhibitor (imatinib)
Driver mutation vs passenger?
Drives cancer development vs random mutation along the way
What base does methylation occur on + what it does + risk factor?
C before a G + prevents DNA from being unwound + C mutation to T
1st and 2nd biggest risk factor for cancer?
Smoking (1st) and obesity (2nd)
High salt intake is linked to which cancer?
Gastric
What % of breast cancer is due to faulty genes?
3%
Can breast feeding reduce breast cancer?
Yes
Beta-carotene (vitamin supplements) ….. risk of cancer?
Increases
Do dairy products increase risk of cancer?
No
2 supplements to recommend + why?
Vitamin D (kids and low sun exposure) and folic acid (pregnancy)
The carcinogen acrylamide is found in which 3 substances?
Coffee, burnt bread and potatoes (crisps,chips etc.)
Coffee prevent which 2 types of cancer?
Liver and endometrial
What are monosomy and trisomy examples of?
Aneuploidy
Most important feature of a test that is being used for cancer screening?
Sensitivity
Abnormalities in MMRPs can be detected by what?
Micro-satellite instability (MIR)
What type of mutation is most likely to activate an oncogene?
Missence
Most cells are in which cell cycle stage?
G0
p53 checks and can arrest the DNA at which 2 checkpoints?
G1/S and G2/M
Variation in meiosis occurs by which 2 mechanisms?
Crossing over and independent assortment of chromosomes
In meiosis, a diploid cell becomes what?
4 haploid daughter cells
Most common type of genetic variation?
Single nucleotide polymorphism (SNP)
What is epigenetic variation?
Changes to the expression of genes without changing the DNA sequence
Most common inheritance of cancer?
Multifactorial
