Card Set Information

2010-11-11 00:05:35

Genetics Mon-Wed
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  1. rare vs. common alleles
    rare mutations -> large deleterious effects; common mutations have smaller effect and milder phenotype
  2. phenotype
    phenotype = genotype + environment
  3. heritability
    the fraction of variation in phenotype that can be explained by genetic factors; NOT static - can vary within populations and over time
  4. familial clustering
    occurring in more members of a particular family than one would expect by random chance. Correlation tied to degree of relatedness?
  5. segregation analysis
    tests whether observedfamily data fit with predicted patterns; goal = determination of inheritance patterns
  6. penetrance
    refers to the proportion of people with a specific allele who exhibit clinical symptoms; not everyone with the disease phenotype have the disease genotype
  7. genetic heterogeneity
    mutations in different genes can lead to the same phenotype (opposite of variable expressivity)
  8. karyotype
    involves staining and analysis of chromosomes
  9. FISH
    fluorescence in situ hybridization; probes for specific sequences on chromosomes; useful for detecting chromosomal abnormalities or large deletions or unbalanced translocation; uses very large probes
  10. VNTR
    variable nucleotide tandem repeat (10s-100s base pair replications); can be used as a genetic marker; used in DNA 'fingerprinting'
  11. STR
    short tandem repeats (2-4 nucleotides per repeat); can be used as a genetic marker; also called microsatellites
  12. SNP
    single nucleotide polymorphism; can be used as a genetic marker
  13. Sanger sequencing
    uses fluorescently labeled dedeoxynucleotides to mark position of specific nucleotides in the genome -> sequencing (put results all together)
  14. point mutation
    single base pair change
  15. silent mutation
    no change in amino acid (but could affect splicing)
  16. missense mutation
    substitutes one amino acid for another
  17. nonsense mutation
    changes an amino acid into a premature stop codon
  18. frameshift mutation
    changes the reading frame of a gene; results in translation of different amino acids
  19. CGH
    comparative genome hybridization; involves array of probes; compares patient DNA to control DNA; able to detect deletions and duplications
  20. gene mapping
    creation of a genetic map assigning DNA fragments to chromosomes; utilizes gene linkage; utilizes genetic markers
  21. LD plot
    triangular plot that measures linkage of specific sections of DNA to each other
  22. association studies of disease
    generally = case-control studies; look at association between genetic markers (SNPs) and allele frequency in case vs. control populations; odds ratio describes strength of association
  23. types of association studies
    candidate-gene and genome-wide association study
  24. candidate gene study
    type of association study in which researchers look at the frequency of specific genes that are suspected to have biological functions related to disease
  25. GWAS
    genome-wide association study; hypothesis-free study that looks at association between genetic markers and alleles in diseased population across the genome
  26. AIS
    ancestry-informative markers; use sample SNP data to determine ancestry of study participants; method of controlling for population stratification
  27. genomic control
    method of controlling for population stratification; involves division of observed test statistic by a certain value (derived from observing other loci in the population that are not suspected to be linked with the allele in question)
  28. TDT
    transmission disequilibrium test; type of analysis for family-based association testing; number of parents who pass on suspected disease-causing allele to affected child is compared to the number of parents who pass on non-disease-causing allele to affected child
  29. Q-Q plot
    can reveal systematic error such as genotyping or population stratification error; deviation from chi-square values under the null hypothesis indicate systematic error
  30. multiple-testing adjustments
    Bonferroni test; permutation tests
  31. common disease-common variant hypothesis
    states that common traits are most likely the result of common (& therefore old) genetic variation
  32. genetic drift
    random fluctuation in allele frequencies due to chance variations; has more noticable effect in smaller populations
  33. assortative mating
    members of a population tend to have children with other members of that population
  34. positive selection
    an environmental force increases the fitness of an allele
  35. allele fitness
    refers to the ability of the allele to be passed on; does NOT necessarily mean that allele is beneficial