ST2 notes Flashcards

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1
Q

allelic heterogeneity

A

different mutations of the same gene

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2
Q

locus heterogeneity

A

same mutation in different genes

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3
Q

Bardet-Biedl syndrome (BBS)

A

15 loci are responsible for cilia functions making it a pleiotropic disorder as many different body systems are impaired

shows locus heterogeneity

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4
Q

pleiotropy

A

one genes influences two or more seemingly unrelated phenotypic traits

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5
Q

Sensorineural deafness

A

same mutation in 28 different genes

autosomal recessive but two different parents can have a normal child if they have different disease genes

normal child will be a double heterozygous as they will have two different mutant genes

shows locus heterogeneity

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6
Q

genomic imprinting

A

offspring’s gene expression is parent-specific due to inactivation of the opposite parent’s allele

caused by DNA methylation that suppresses transcription resulting in alterations in gene expression

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7
Q

imprinted gene

A

methylated and inactive in somatic cells

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8
Q

maternal imprinting

A

maternally derived allele inactivated

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9
Q

paternal imprinting

A

paternally derived allele inactivated

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10
Q

Prader-Willi syndrome

A

maternal imprinting

deletion of paternal chromosome 15q11

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11
Q

Angelman syndrome

A

paternal imprinting

deletion of maternal chromosome 15q11

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12
Q

uniparental disomy

A

two copies of a chromosome are inherited from one parent and no copies from the other parent

caused by non-disjunction followed by loss of genetic information

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13
Q

heterodisomy

A

meiosis I non-disjunction

both homologs from one parent

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14
Q

isodisomy

A

meiosis II non-disjunction

one chromosome is duplicated

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15
Q

modifier gene

A

gene that alters the expression of a human gene at another locus that in turn causes a genetic disease

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16
Q

epistasis

A

effect of a gene mutation is dependent on the presence or absence of mutations in one or more other genes (modifier genes)

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17
Q

linkage analysis

A

family-based

makes use of pedigrees for mapping of monogenetic diseases

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18
Q

association analysis

A

population-based mapping comparing the frequencies of alleles in affected individuals to unaffected controls for complex diseases

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19
Q

haplotype

A

series of alleles at linked loci that are co-inherited on a single chromosome

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20
Q

recombination frequency (theta)

A

estimate of genetic distance

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21
Q

theta = 0.5

A

NR = R

loci very far apart

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22
Q

theta = 0

A

only NR

loci very close together

23
Q

theta < 0.5

A

NR>R

in-between

24
Q

LOD score (Z)

A

likelihood ratio / odds ratio

25
Q

Z > or equal to 1

A

suggests linkage

26
Q

Z > or equal to 3

A

strong evidence of linkage

27
Q

Z < 1

A

suggests linkage less likely

28
Q

Z < -2

A

significant evidence against linkage

29
Q

exome

A

all the exons in all of the genes in an individual’s body

30
Q

complex/multifactorial diseases

A

caused by many different genetic factors - polygenic

influenced by environmental and chance factors

disease manifests once certain threshold is reached

31
Q

polygenic

A

inheritance and expression of a phenotype is determined by many different genes at different loci

32
Q

continuous/quantitative traits

A

normal phenotypic characteristics that everyone has but with differing degrees

can be measured - height, blood pressure

33
Q

discontinuous/dichotomous/qualitative traits

A

disease is either present or absent

congenital disease or diseases that develop later in adult life

predisposition is inherited - relatives share more susceptibility genes and environmental factors

34
Q

empiric risk

A

chance that a disease will occur or reoccur in a family

higher risk for more closely related individuals

35
Q

heritability

A

indicates the importance of genetic factors compared to environmental factors

36
Q

familial aggregation

A

affected individuals cluster in families

indicates genetic component - families have predisposition for qualitative diseases because of shared alleles

37
Q

relative risk (lambda)

A

measures familial aggregation

lambda = prevalence of disease in relative of affected person/prevalence of disease in general population

larger lambda = greater familial aggregation

lambda = 1 - recurrence risk for relatives of affected individual is the same for any other individual in the general population

38
Q

common disease-common variant hypothesis

A

disease risk in specific individuals is due to aggregation of common variants

39
Q

common disease-rare variant hypothesis

A

rare variants are expected to be more deleterious and high penetrant

40
Q

protective factors/variants

A

reduce the risk for common disease

protective factors for one disease can be a susceptibility factor for another disease

41
Q

gene therapy

A

genetic alteration of the cells of a patient with a genetic disorder to achieve a therapeutic effect

42
Q

gene augmentation

A

replaces a missing gene product by inserting a normal gene into a somatic cell

best for LOF mutations

43
Q

gene silencing

A

targets pathogens in infectious diseases

silences active oncogenes

silences GOF mutant alleles in inherited diseases

44
Q

in vivo

A

cells are modified within the patient’s body

difficult to monitor success

45
Q

ex vivo

A

cells are removed from patient, genetically modified in cell culture, selected, multiplied and returned to patient

cells can be analyzed in depth before treating patient

46
Q

non-viral delivery

A

synthetic vesicles known as liposomes form spontaneously when certain lipids are mixed in aqueous solution

lipid coat allows DNA to survive in vivo, it binds to cells and allows DNA to enter

can accept large DNA inserts

does not elicit immune response

efficiency of transport low

47
Q

malignant neoplasia/cancer

A

consequence of genetic damage whose cumulative effect results in unrestrained cell growth, tissue invasion, and metastasis

48
Q

sarcoma

A

mesenchymal tissue - fat, bone, muscle

49
Q

carcinoma and adenocarcinoma

A

epithelial tissue

50
Q

leukemia and lymphoma

A

blood forming tissue

51
Q

pronto-oncogenes

A

components of signaling pathways that regulate cell proliferation and differentiation

52
Q

tumor suppressor genes

A

block uncontrolled cell proliferation

participate in pathways that regulate the cell cycle

regulate upstream growth signaling pathways

may induce apoptosis

53
Q

gatekeepers

A

classical tumor suppressor

central role in regulating cell proliferation by regulating cell cycle and growth

mutations lead directly to tumor development