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Module 1 > Genetics > Flashcards

Genetics Flashcards

1
Q

Familial risks

A

What is the incidence of a disorder in relatives compared to the incidence in the general population?

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2
Q

Twin studies

A

What is the incidence in monozygotic compared to dizygotic twins?

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3
Q

Adoption studies

A

What is the incidence in adopted children of the disorders which their parent had?

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4
Q

Population and migration studies

A

What is the incidence in people from a particular ancestry group when they move to a different geographical area?

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5
Q

Huntingdon’s disease

A
  • Autosomal dominant disease with high penetrance
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6
Q

Huntingdon’s features

A
  • Progressive degenerative disorder of the CNS - dementia, movement disorder, personality changes
  • Incurable, treatment for symptoms only
  • Mutations due to CAG repeat expansion
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7
Q

Huntingdon’s Peak age of onset

A

40 years

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8
Q

Huntingdon’s transmission

A

Vertical transmission

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9
Q

Anticipation

A

Age of onset can decrease with generations

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10
Q

Huntingdon’s aetiology

A

11 - 34 CAG repeats are normal –> encodes run of 11 - 34 glutamine amino acid residues in the protein
A run of > 35 glutamine residues causes the protein to aggregate in the brain cells –> progressive cell death
>35 CAG repeats in the gene expand further (esp in male meiosis) –> earlier age of onset in children of affected men - anticipation
Toxic-gain-of-function genotype

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11
Q

Penetrance

A

the chance that a genotype results in the associated phenotype

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12
Q

Hereditary Haemochromatosis

A

Autosomal recessive condition characterised by iron overload

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13
Q

Hereditary Haemochromatosis aetiology

A

Due to mutations of HFE gene –> missense mutations, single nucleotide polymorphisms, point mutations
–> change in amino acid - specifying codon
Recessive diseases are usually assoc w/ mutations that cause loss-of-normal-protein function

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14
Q

Hereditary Haemochromatosis Presentation

A

Life threatening disease associated with high morbidity and mortality
Iron overload –> organ damage
- Regular venesection provides an effective treatment - quantitative reduction in iron stores

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15
Q

Expressivity

A

Degree to which the range of signs/symptoms for a given trait differ between individuals

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16
Q

Pleitropy

A

mutations in a single gene can influence multiple phenotypic traits

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17
Q

Polygenic inheritance

A

the inheritance and expression of a phenotype being determined from many genes at different loci (small additive effects)

18
Q

Multifactorial disorders

A

Require interaction of environment and genetic factors to manifest

19
Q

Proband

A

1st individual in investigation of related patients with an inherited disorder

20
Q

The genome

A 
3 million base pairs
Packaged in chromosomes
~ 21,000 protein coding genes
alternate gene splicing
Non-coding RNAs
21
Q

Tandem repeat

A
  • short sequences of DNA repeated in head to tail fashion
  • mini/micro satellites
  • variable number of tandem repeats are very polymorphic
22
Q

Polymorphism

A

A variant that is common enough to affect more than 1% of chromosomes in a given population

23
Q

Human Genome Project

A

1990 - 2003
Mapping variation and functional effects
3 Billion base pairs + 21,000 coding genes

24
Q

Types of SNV/SNP in coding DNA

A

Silent mutation
Stop codon
Missense (diff amino acid created)

25
Q

Pharmacogenetics

A

Studying individual variants to predict response to medicine or to guide prescribing

26
Q

Pharmacogenomics

A

Analysing genome-wide variants in an individual or a population to identify markers that predict response

27
Q

Meitotic nondisjunction

A

Failure of tow members of a chromosome pair to separate from one another during meiosis –> both chromosomes go to a single daughter cell

28
Q

Patau’s Syndreom

A

Trisomy 13

- Mental retardation, growth failure, low-set ears, deafness, microcephaly, cleft lip and palate, septal defects

29
Q

Edward’s Syndrome

A

Trisomy 18
- V. small head, back of head prominent, malformed ears, small mouth and jaw, hands clenched into fists, clubfeet, webbed toes

30
Q

Down’s Syndrome

A

Trisomy 21
- Broad, flat face, epicanthic eyefold, short nose, short and broad hands, small and arched pa;ate, growth failure, mental retardation

31
Q

Turner’s Syndrome

A

Monosomy X
Short stature, low hair line, webbed neck, constriction of aorta, undeveloped breasts, shield-shaped thorax, elbow deformity

32
Q

Aneuploidy

A

when an organism gains/loses a chromosome

–> occurs during meiosis/mitosis, usually non-disjunction

33
Q

Risk factors for aneuploidy

A

Increasing maternal age, maternal hypothyroidism, irradiation, viral infection, familial tendency

34
Q

Splicing mutation

A

Sequence that guides introns from mRNA are mutated - abnormal splicing.
Translated protein may carry intron sequences –? alterd amino acids incorporated into polypeptide chain

35
Q

DNA Primary Structure

A

Chains of nucleotides held by phosphodiester bonds attaching the phosphates

36
Q

DNA Secondary Structure

A

2 DNA strands held together by H bonds between complimentary base pairs

37
Q

DNA Tertiary Structure

A

Packaging - DNA is wrapped around histones, forming chromatin. Chromatin is packed into nucleosomes and then supercoiled into a chromasome

38
Q

3 types of RNA in eukaryotic cells

A

mRNA - messenger
tRNA - transfer
rRNA - ribosomal

39
Q

Messenger RNA

A

copied from DNA and used as template for protein synthesis

40
Q

Transfer RNA

A

small molecules which transfer amino acids to the ribosomes for protein synthesis

41
Q

Ribosomal RNA

A

involved in binding mRNA and tRNA during protein synthesis

42
Q

In RNA which nitrogen base has changed

A

thymine –> uracil

Module 1 (12 decks)

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