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24 Cards in this Set
- Front
- Back
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general progress of cancer with respect to genetic mutations
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Single mutation arises--> second mutation arises, forms adenoma--> third mutation creates carcinoma, which metastasizes, undergoes further mutations
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two-hit theory (cancer)
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certain heritable genes make one susceptible to cancer- mutation in normal allele produces tumor
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continuous vs dichotomous traits
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a continuous trait is like height or weight
a dichotomous trait is like hypertension or obseity- you are above or below the cutoff |
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in what situation could an autosomal dominant trait skip a generation
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the trait may have incomplete penetrance (e.g. could be absence of other genes necessary for phenotype)
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What does compound heterozygosity mean
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two alleles are different, but both cause phenotype
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Discuss trinucleotide repeat disorders and concept of anticipation
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e.g. CAG repeat in Huntington gene
enough repeats causes silencing of gene, leads to phenotype anticipation- increased likelihood of adding more repeats in later generations |
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Heteroplasmy is another word for what?
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mosaicism
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discuss genetic imprinting from one generation to the next
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genetic imprinting (methylation- inactivation of certain genes) is reset during germ line genesis
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What is wrong in genomes of individuals with Prader-Willi syndrome? Angelman syndrome?
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uniparental disomy of chromosome 15- maternal and paternal, respectively
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What is a phenocopy?
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non-genetic conditions mimicking a genetic disorder
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Describe the difference between allelic heterogeneity and nonallelic heterogeneity
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Allelic heterogeneity- different mutations in same locus cause similar phenotypes (think CFTR mutations here)
Nonallelic heterogeneity- different mutations in different loci cause similar phenotypes |
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What is phenotypic heterogeneity?
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Allelic mutation causes more than one phenotype
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What are the general characteristics of SNPs?
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they are usually benign, can be synonomous (same a.a.) or not, but can have functional consequence in protein or mRNA processing
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What is a haplotype?
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ordered list of alleles of multiple loci on single chromosome
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What is the concept behind positional cloning?
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Identify individuals with a particular phenotype and then map/clone their DNA--> identify loci of interest, then mutation
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Explain the difference between linkage analysis (2 types) and allelic association studies
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linkage analysis- parametric (Mendelian inheritance) and nonparametric analysis (no assumption about mode of inheritance)
allelic association study- compare frequency of allele in affected and unaffected populations |
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What are some methods to confirm heritability of a phenotype
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twin studies, adoption studies, examine how often phenotype presents between related pairs
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Positive result from allelic association study implies what?
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Marker that is associated with phenotype represents disease allele or is linked to the diseased allele
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Discuss characteristics of genetic markers: microsatellites, STRPs, and SNPs
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microsatellites- 80% heterozygosity
STRPs- high mutation rate, not easily automated SNPs- low heterozygosity, ideal for haplotyping |
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Describe copy number variants
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deletions, insertions, duplications >1kb
loss of heterozygosity occurs due to deletions |
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What is linkage disequilibrium?
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measure of association of alleles on a chromosome-- essentially, occurs when two genes/markers are linked
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What did we learn from HapMap?
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there is more association in "newer" populations (non-African) because of less total recombination events that have occurred in the population
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What are htSNPs and what are their significance?
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For many haplotypes, the identification of a few SNPs- htSNPs--serve as a proxy for all SNPs of that haplotype
make genotyping more efficient |
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What are the two stages of a genome-wide association study?
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Stage 1- exploratory stage with phenotypic individuals
Stage 2- larger sample size (to reduce false positives), more representative of population |
