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POD Test Two > Genetics 3 Lecture > Flashcards

Genetics 3 Lecture Flashcards

1
Q

Define multi-factorial disorders

A

Disorders with multi-factorial inheritance result from teh combined effects of two or more mutant genes combined with environmental factors

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2
Q

What are characteristics of these disorders?

A

Risk of expression is conditioned by the number of mutant genes inherited
Environmental influences significantly increase the risk of expression
Risk of recurrence of the disorder in first-degree relatives in 2-7%
Risk of recurrence in subsequent pregnancies increases with the birth of each affected child

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3
Q

Types of cardiovascular diseases?

A

Congential heart disease, ischemic heart disease, hypertensive heart disease (systemic and pulmonary), valvular heart disease, nonischemic (primary) myocardial disease

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4
Q

What causes cardiovascular disease?

A

Complex interplay of genetics and environmental factors that disrupt networks controlling:

    • morphogenesis (myocyte survival)
    • biomechanical stress responses
    • contractility (electrical conduction
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5
Q

What is type 1 diabetes?

A

Beta cell destruction

Leads to absolute insulin deficiency

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6
Q

What is type 2 diabetes?

A

Insulin resistance with relative insulin deficiency

  • Genetic defects of beta cell function causes lots of mutation
  • Genetic defects in insulin processing or insulin action, caused by insulin gene and receptor mutations
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7
Q

What are sites of expansion and the affected sequence in selected diseases caused by?

A

nucleotide repeat mutations

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8
Q

Cause of Progressive Myoclonus Epilepsy?

A

Not strictly tri-nucleotide repeats

- Usually heritable DNA expands typically in the promotor region

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9
Q

Define triple repeat mutations

A

Fragile X syndrome

  • Mutation on the C
  • – 200 CGG repeats, methylation of the promoter and activation –> mental retardation
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10
Q

Define mutations in the mitochondrial genes?

A

Leber hereditary optic neurpathy
- Maternally inherited bc ova contains significantly higher number of mitochondria than spermatozoa–> blindness, neurological dysfunction, cardiac conduction defect

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11
Q

What is genomic imprinting?

A

Uniparental disomy
Characterized by differential activation of maternal and paternal alleles of certain genes
–> Prader willi syndrome (deletion of arm of chromosome 15 affects paternal –> metal retardation, short stature, obesity)

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12
Q

What is gonadal mosaicism?

A

affect cells destined to form gonads during early embryogenesis

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13
Q

What are chromosomal disorders due to?

A

Alterations in the number of chromosomes
Alterations in the structure of the chromosomes
- Result from errors during cell division

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14
Q

Define monosomy

A

Associated with on less chromosome

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15
Q

Example of monosomy?

A

Turner syndrome

  • Monosomy of X
  • Lymph edema of neck, hand, and feet, broad chest, failure of chest development, ovaries fibrous, congenital heart disease
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16
Q

Define trisomy

A

Associated with one extra chromosome

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17
Q

Example of trisomy?

A

Down syndrome
Trisomy 21
- Flat faces, mental retardation, congenital heart disease, acute leukemia, premature Alzheimer’s

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18
Q

Define mosaicism

A

Associated with one or more populations of cells, some with normal chromosomal complement, others with extra or missing chromosomes

19
Q

Define deletion

A

Loss of a terminal or interstitial segment of a chromosome

20
Q

Define translocation

A

Transfer of a segment of one chromosome to another

21
Q

Define isochromosome

A

Formed when on arm is lost and the remaing arm is duplicated

22
Q

Define Inversion

A

Rearrangement associated with two breaks in a chromosome, followed by inversion and reincorporation of the broken segment

23
Q

Define ring chromosome

A

Deletion affecting both ends followed by fusion of the damaged end

24
Q

What does the diagnosis of genetic diseases involves?

A

Cytogenetic or molecular analyses

25
Q

Define cytogenetic analysis

A

Microscopic analysis of the number and structure of chromosomes in individual cells that are associated growth, development and body functions

26
Q

What is a prenatal cytogenetic analysis?

A

Preformed on fetal cells obtained by amniocentesis or chorionic villus biopsy

  • Advabced naterbak age
  • A parent with a structural chromosomal abnormality
  • Previous child with chromosomal abnormality
  • A parent who is carrier of an X-linked disease
27
Q

What is Fluorescence In Situ Hybridization?

A

Interphase nuclei stained with a fluorescent probe that hybridizes to chromosome 20

  • Each nuclees reveals three dots representing three copies of the chromosome
  • – Normal cells only have 2
28
Q

What is postnatal cytogenetic analysis

A 
Period after birth
Performed on peripheral blood lymphocytes
- Multiple congenital anomalies
- Unexplained mental retardation
- Suspected chromosomal abnormalities
- Suspected fragile X syndrome
- Infertility
- Recurrent abortion
29
Q

Define Di George Syndrome

A

Deletion on chromosome 22

30
Q

Define chromosome painting

A

An extension of FISH using multicolor FISH in a child with an undetermined abnormality
- Shows any difference in the chromosomes based on color

31
Q

Define molecular analyses

A

Two different approaches are applied to the diagnosis of genetic diseases by recombinant DNA technology

32
Q

Define direct gene diagnosis

A

Involving detection of the mutant gene

33
Q

Define indirect gene diagnosis

A

Involving detection of linkage of the disease gene with a harmless marker gene

34
Q

Define Polymerase Chain Reactions

A 
Denature
Anneal 
Extend 
Repeat
(around 20 cycles)
2 > 4 > 8 > 16 > 32
35
Q

Define southern blot analysis

A 
Digest DNA 
Separate fragments
Transfer for further analysis
Synthesis labeled cDNA probe
Hybridize denatured probe
Wash the membrane
36
Q

Define restriction analysis

A

Detection of coagulation factor V mutation by PCR
G –> A substitution in an exon destroys one of the two Mnl1 restriction sites
– Gives rise to two rather than three fragments

37
Q

What is Fragile X syndrome

A

All sons are normal, females are carriers
In oogenesis, premutation expands to full mutation –> all sons are affected and only 50% of females affected are actually affected
- Amplifications of the DNA by primers that flank the region affected by trinucleotide repeats generate products of different sizes when DNA from normal carrier males and affected individuals is compared

38
Q

PCR recognizes?

A

mutations that affect the length of the DNA

39
Q

Define oligonucleotide probe analysis

A

Used when the point mutation producing the abnormal gene does no alter any known restriction site

  • Two ons having the single base that differs –> hybridizes to the normal gene but not the other gene
    • Detemine based on strength of binding
40
Q

Define microarray-based DNA sequencing

A

A low power digitized scan of a gen chip that is no larger than a nickel in size but is capable of sequencing thousands of base pairs of DNA
A high resolution view of the gen chip illustrates hybridizaiton patterns corresponding to a stretch of DNA sequence (upper: wild-type.. lower: mutation)

41
Q

Define indirect gene diagnosis

A

Gene Tracking
Takes advantages of variation sin DNA near a mutated gene
- Result from differences in specific nucleotides or number of nucleotide repeats
Site polymorphisms (restriction fragment length polymorphism) result from DNA polymorphism that give rise to fragments of different lengths in Southern blot

42
Q

Define Linkage Analysis

A

PCR based application to detect progeny carrying the disease gene
- Useful in presymptomatic diagnosis of several genetic disorders (cystic fibrosis, huntingtons, polycycstic, fragile X syndrome)

43
Q

What are limitations of indirect gene diagnosis?

A

Several affected and unaffected family embers needed
Key family members must be heterozygous for the polymorphism
Length polymorphisms have multiple alleles, great chance of heteozygosity
Recombination between homologous chromosomes –> loss of linkage between DNA polymorph and mutant

POD Test Two (8 decks)

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