L10

Question 1

What is needed to get COMPLETE map of genome?

Answer 1

1. Genetic maps

2. Physical maps

Question 2

Compare and contrast genetic vs. physical maps

Answer 2

1. Genetic maps
   - Recombination frequencies btwn markers (must be variable btwn individuals)
   - Linkage
   - Map disease genes w/rspt to neutral markers
2. Physical maps
   - Describe location of DNA sequence
   - Allow molecular info to be determined

Question 3

How to get from disease to gene via maps?

Answer 3

1. Family studies
   - > genetic mapping
2. Chromosome interval
   - > clone maps
3. Large-insert clones
   - > expression maps
4. Candidate genes
   - > gene sequencing
5. Disease mutation

Question 4

Compare monogenic and complex disorders

Answer 4

1. Monogenic disorders
   - Caused by a single gene mutation.
   - inheritance pattern: dominant or recessive (100% penetrance)
2. Complex disorders
   - influenced by many genes
   - inteheritence pattern: complex

Question 5

4 strategies for eludication of monogenic disorders

Answer 5

1. Breakpoint mapping in disease-associated balanced chromosome rearrangements
2. Detection of microdeletions and duplications by array CGH
3. Linkage or homozygosity mapping by array-based SNP typing

Question 6

What is next gen sequencing

Answer 6

NGS platforms perform massively parallel sequencing, during which millions of fragments of DNA from a single sample are sequenced in unison

Question 7

2 ways to identify candidate genes?

Answer 7

Cloning can be position-independent or position-dependent (more common)
Positional information narrows the # of genes to be tested
When a candidate is found, one determines if the gene is involved in the disease by searching for mutations in affected individuals

Question 8

Position-independent strategies: Candidate gene approaches

Answer 8

Usually determined through speculation on the nature of the gene product based on phenotype
Examples:
phenylalanine hydroxylase for PKU
-globin gene in sickle-cell anemia
Knowing or speculations about protein product then allowed researchers to identify gene
phenylalanine hydroxylase for PKU
-globin gene in sickle-cell anemia

Question 9

Position-independent cloning

Answer 9

Possible if information about protein product, DNA sequence or function is known
Partial amino acid sequence can be used to predict DNA sequence
Synthetic oligonucleotide can be used to hybridize to screen cDNA libraries
Can raise an antibody against the purified protein, then screen a cDNA expression library
– cDNA library in which the inserts are transcribed and translated and the protein can be detected with an antibody
These cases are rare in human genetics; usually positional cloning is used