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Pathology 2 > 1.1 Genetics > Flashcards

1.1 Genetics Flashcards

1
Q

human genes

A

25,000 - less than twice as many as a worm –> alternative splicing?

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2
Q

percentage of shared genome btw 2 people

A

99.50%

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3
Q

the 0.5% of difference in humans indicates

A

polymorphisms, muations - 15million base pairs

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4
Q

most common polymorphism

A

SNP - single nucleotide polymorphism –> 6 x 10^6 are known

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5
Q

SNPs are usually biallelic meaning

A

only 2 choices at a given site withing the population

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6
Q

Are SNPs mutations?

A

NO - they do not totally remove activity

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7
Q

less than 1% of SNPs occur in

A

coding regions meaning that most will have to undergo linkage analysis that may prove to be significant

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8
Q

linkage disequilibirum

A

bc less than 1% of SNPs occur in coding cregions, SNPs are most often co-inherited as a marker linked to a gene causing disease

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9
Q

CNPs

A

copy number variations - can be bi-allelic or multipel - 50% involve gene coding sequences, genes involved in immune system and CNS over represented in containing CNPs, much less is known about CNPs and disease susceptibility than SNPs

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10
Q

when you see an SNP in 90% of a disease population

A

that is significant information bc you can look to see if that SNP is linked with a gene that causes the disease

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11
Q

genetics

A

study of single genes

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12
Q

genomics

A

study of entire genome and interactions

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13
Q

how do you use DNA chips

A

can use them to study tumor vs normal tissue or stimualted cells vs control cell

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14
Q

Proteonomics

A

study of all of the proteins in a tissue/cell 2d electrophoresis/mass spec. or isotope coding affinity tags (heavy and light isotopes and mass spec) –>not every thing that transcribed is translated into protein so studying proteins is very important

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15
Q

laser capture microdissection

A

if you have a tumor, remember it is normal to have vessles and stromal tissue so you used this micordisection to just cut out the tumor cells

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16
Q

microarrays

A

you can do a blind scree just by hybridizing dna testing for thousands of genes, looking at diseased vs no disease – then you can go and look at the genes and make a hypothesis

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17
Q

with microarrayes the colors mean something

A

red - tumor dna, green- normal dna, yellow -mixed dna

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18
Q

functional cloning - classical approach

A

gene product and defect are known - you clone the normal gene, make probes, clone and sequence the gene from affected individuals (many metabolic disorders)–find a way to fix it

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19
Q

positional cloning - candidate gene approach

A

gene is not known - uses cytogenetic or SNP marker to localize candidate genes to a narrow area of a chromosome, clone DNA from that area express normal and disease products – find out what’s wrong

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20
Q

cloning and the production of ultra pure proteins examples

A

insuline, factor 8, soluble TNF receptor, humanized antibodies

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21
Q

gene therapy is complex because

A

cannot anticipate for all factor – SCIDS (gamma cahin of cytokine receptor) gene inserted next to host gene regulating cell growth _. Gave the patient T-cell leukemia

22
Q

how insuline was adjusted

A

first we made insuline from pigs, but we were making reactive Ab against the pig inuline so we made human insuline, but if it wasn_t refridgerated it would not be effective and pts were not getting their full dose, so now things are added to it to make it heat stable

23
Q

With rhematoid arthritis why is giving the Abs to TNF bad

A

the Abs will clear the TNF so that is good to reduce inflammation, but if you have TB and you need to wall it off you need TNF to maintain the granuloma and if you don’t then you can’t maintain it — so you need to make sure that the person doesn’t have TB or that they are vaccinated to make sure anti-TNF treatment is appropriate (also given in Psoriasis)

24
Q

sickle cell treatment

A

could be treated by giving normal Hg cells but its not a thrapy

25
Q

Anti amyilid Ab in alzhimers

A

if animal is immunized with Ab towards tau that causes plaques alzheimers can be reversed, but in humans if immunized with the Ab they got inflammatory encephalitis and some people die

26
Q

RNA analysis

A

many alteration in DNA are single gene effects so copy number is low. mRNA has higher copy number if gene is transcribed. Many genes are rearranged (BCR-ABL) over larger areas than PCR can replicate, but looking for the mRNA that is formed after splicing and cutting is easier.

27
Q

Epigenetic effects include

A

DNA methylation, histone acetylation, miRNAs –> we know genetic alterations in DNA seq cannot explain the diversity of human phenotypes such as phenotypic difference in monzygotic twins – so we look at epigenetc changes

28
Q

too much miRNA and cancer

A

too much scilencing of tumor suppressor genes can lead to cancer

29
Q

too little miRNA and cancer

A

too little scilencing of oncogenes can lead to cancer

30
Q

Congenital

A

means present at birth. If you are starved for air during birth and you have massive CNS problems it is congenital NOT genetic. Congenital diseases may or may not be genetic.

31
Q

Familial

A

multifactorial diseases that run in families but show no inheritance patterns

32
Q

Hereditary

A

gene passed down

33
Q

Genetic

A

involves genes

34
Q

Prevalence of chromosomal abnormalities

A

50% of spontaneous abortions contain a chromosomal abnormaility–the earlier the abortion, the more likely a chromosomal abnormality. 1% of live births have an identifiable chromosomal abnormalitiy. Chromosomal abnormalities visible, other mutations are not. 5% of individuals less than 25 develop a disease with a significant genetic component –but these are not chormosomal

35
Q

interplay of genetics and environment

A

the most common diseases afflicting man have goth genetic and environmentla components (diabetes, atherosclerotic heart disease, cancer, obesity)

36
Q

which diabetes has a stronger genetic component

A

type 2 but also has a strong environmental compoent like obesity

37
Q

genes and environment leading to disease

A

lots of genetic w/ few environmental factors, lots of environmental with few genetic factors, or lots of genetic and environmental factors will lead to diseas — usually one genetic and one environmental factor is not going to lead to disease

38
Q

point mutations

A

occur bc the DNA code is degenerate – missence, nonsense, promoter activation/inactivation

39
Q

missense

A

AA substitution, full lenth protein made, variable preservation of structure and function

40
Q

Nonsense mutation

A

AA change introducing a stop codon

41
Q

Point mutations in Sicle cell

A

DNA: CTC to CAC , RNA: GAG to GUG, AA: Glutamic acid to Valine

42
Q

deletions or additions result in

A

fame shifts

43
Q

examples of triple expansion repeats

A

Huntington, Fragile X, —- mostly repeating CG sequences

44
Q

What kind of mutations are more common?

A

loss of function bc it is easier to destroy something than give it an alternative fn. altered gene product that affects other proteins (dominant negative), gain ro altered function (rarer, Huntington disease)

45
Q

Mendelian Disorders

A

single gene alterations, predictable inheritance pattern, Pleiotrophism (single gene with multiple effects - Marfans), Heterogenetity (multiple genes same effect: profound deafness)

46
Q

Patterns of inheritance

A

autosomal dominant, autosomal recessive, x-linked, multifactorial

47
Q

What form do you see disease in AD cases

A

Heterozygotes – homozygotes are usually fatal

48
Q

Children of one affected AD parent

A

have 50% cance of developing the disease

49
Q

Autosomal Dominant and new mutations

A

some patients do not have an affected parent –new mutations account for variable percentages of cases. Usually older males increase the incicence of mutations in sperm – 30% of marfan’s is denovo

50
Q

Penetrance

A

percentage of individuals with the gene that have the disease – we only consider penetrance with autosomal dominant cases

51
Q

Variable expression

A

all individuals have the disease but different severity or character

Pathology 2 (15 decks)

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