Genetic Testing Oct13 M2

Question 1

example of disease with incomplete penetrance

Answer 1

breast cancer

Question 2

allelic heterogeneity def

Answer 2

disease can be caused by diff mutations in same gene

Question 3

locus heterogeneity def

Answer 3

disease can be caused by mutations in multiple genes

Question 4

some reasons for genetic testing (4)

Answer 4

• check if carrier
• check if susceptible for a disease known in the family
• confirm diagnosis
• targeted therapy

Question 5

genetic tests other than karyotyping, FISH and microarrays (3)

Answer 5

sanger sequencing, panel sequencing, exome or genome sequencing

Question 6

how see a translocation with FISH

Answer 6

will see the two fluorescent colours on same chromosome rather than separated

Question 7

other name for microarrays

Answer 7

array comparative genomic hybridization (aCGH)

Question 8

aCGH resolution

Answer 8

can be as small as exon. Can detect copy number variants in range of 10kb

Question 9

Sanger sequencing scale and principle

Answer 9

1 or few genes. PCR amplification and sequence after

Question 10

next generation sequencing scale and principle

Answer 10

whole genome. take whole genome, fragment it in 100-500 pieces and sequence each piece

Question 11

Illumina protocol

Answer 11

make library of DNA, put pieces on slide (2G pieces), sequence all

Question 12

Illumina sequencing how errors avoided and how all put together

Answer 12

DNA is sequenced 30-100x in one sequencing. Bioinformatics align sequences.

Question 13

human genome length

Answer 13

3 billion nucleotides

Question 14

human genome coding portion % and length

Answer 14

50 million bases of DNA. 1.5-2%

Question 15

number of genes in genome

Answer 15

20 000

Question 16

why exome sequencing over genome sequencing

Answer 16

less expensive, 85% disease mutations in coding regions

Question 17

exome sequencing: important thing we need

Answer 17

probes for all protein coding portions of the genome

Question 18

exome sequencing principle

Answer 18

hybridize genome with all the probes. sequence what’s attached

Question 19

sanger pros and cons

Answer 19

pros: fast, accurate
cons: very specific, have to know what we want

Question 20

panel sequencing pros and cons

Answer 20

use when disease is heterogeneous

Question 21

genome sequencing cons

Answer 21

expensive and not sure how to intepret non coding regions

Question 22

important eventual benefit from genetic testing

Answer 22

provide diagnosis (often no diagnosis or wrong)