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37 Cards in this Set

  • Front
  • Back
Define Segregation
The transmission of genes from generation to generation.
What is cosegregation?
The transmission of more than one gene together.
What is linkage?
The increased likelihood of two genes being transmitted together because they're close on the same chromosome.
What are 2 things that determine the likelihood of linkage?
-Distance between loci
What are the 2 configurations of alleles in an individual that is heterozygous for 2 autosomal recessive genes that are linked?
AB/ab (cis)
Ab/aB (trans)
What would be the frequency of gametes produced by this individual if they are cis?
50% AB
50% ab
What would be the frequency of gametes produced by this individual if they are trans?
50% Ab
50% aB
What happens to gene transmission of 2 loci that are farther than 50 cM apart?
They get transmitted to offspring gametes randomly and independently.
What happens to gene transmission of 2 loci that are less than 50 cM apart?
They get transmitted together more frequently than predicted by chance.
What is a typical LOD score that indicates likely linkage?
What is a LOD score that is against linkage?
What allows visualization of a linked marker?
If it shows up in consanguinous marriage children, but not in normal marriage's children.
What is the most common lethal genetic disease of childhood? How many births is it seen in?
Cystic fibrosis - in 1/1000 live births
What type of inheritance is Cystic fibrosis?
Autosomal recessive
What method was used to identify the CF gene?
Positional cloning
What are the 4 tissues in which only gene CFTR is abnormal in all of them?
-Sweat glands
What results from Cystic fibrosis in the lungs?
COPD - increased mucus
What does CFTR stand for?
Cystic fibrosis transmembrane conductance regulator
What is the conductance regulator?
A chloride channel that is responsible for salt balance.
Why is it important to know that Positional cloning was used to identify the CFTR gene?
Because it was the first disease gene identified via this technique.
How many known mutations cause cystic fibrosis?
Over 120
What type of gene defect causes Hungtington's disease?
Polyglutamine tracts - accumulations of Glutamine.
What type of inheritance is Huntington's disease?
Autosomal dominant
What type of genetic analysis localized the Huntington disease gene to the tip of Ch' 4?(in 1983)
Linkage analysis
How was the huntingtin disease gene itself identified in 1993?
By exon trapping
What category are polyQ diseases like Huntington's disease an example of?
Triplet expansion diseases
What are All triplet expansion diseases? What do they all affect?
-All affect the brain
What are 4 triplet expansion diseases?
-Fragile X
-Kennedy syndrome
-Myotonic dystrophy
What can be defined for each triplet expansion disease?
A threshold of # of repeats over which the symptoms appear and degeneration ensues.
What do we call disorders like cystic fibrosis and PolyQ diseases, where we can identify the gene itself?
Monogenic disorders
How are polygenic disorders different from monogenic?
They are affected by
-multiple genes
-environmental factors
What problems result for genetic analysis in polygenic disorders?
-Individual genes don't have a huge impact - and for those genes that do, huge families are needed for studies.
Why do multi-generational pedigrees need to be recruited for genetic analysis of polygenic disorders?
Because most of these disorders develop later in adulthood.
When Linkage analysis is used for studying polygenic diseases, what does it result in identifying?
Quantitative trait loci - QTL
What is a QTL?
A large region of DNA.
What is linkage analysis useful for?
Identifying loci that contribute to both monogenic or polygenic disorders
What is linkage analysis MOST powerful for identifying?
Genes with large phenotypic effets - monogenic.