genetic epidemiology ch1

Question 1

epidemiology

Answer 1

the study of the distribution, determinants [and control] of health-related states and events in populations

Question 2

genetic epidemiology

Answer 2

a discipline closely allied to traditional epidemiology that focuses on the familial, and in particular genetic, determinants of disease and the joint effects of genes and non-genetic determinants. Crucially, appropriate account is taken of the biology that underlies the action of genes and the known mechanisms of inheritance (the manner in which the biology must be incorporated into any particular analysis varies markedly between studies and depends on the genetic information available)

Question 3

complex disease

Answer 3

characterized by a multitude of interacting genetic and environmental determinants; complex diseases include diabetes mellitus, ischaemic heart disease, asthma and cancers

Question 4

genetic markers

Answer 4

DNA sequences that vary from individual to individual; can be localized to particular sites in the genome [but not necessarily responsible for a trait]

Question 5

genetic linkage analysis

Answer 5

based on concept that the marker and causative variant may or may not be within same gene; is foundation of many breakthroughs in disease genetics

Question 6

systematic approach to the identification and characterization of the genetic determinants of a complex disease

Answer 6

recurrence risk ratios; correlations [is there evidence of phenotype aggregation within families?]
variance components; heritability [ is the pattern of aggregation consistent with an effect of genes?]
segregation analysis [is there evidence of a gene with substantial enough effect to justify expensive studies to attempt to identify it?]
linkage analysis [where is the causative gene most likely to lie in the genome?]
association analysis; LD mapping; haplotype analysis [can we be more precise about its position? is there a causative polymorphism? is there an identifiable ‘haplotype block’?]
gene expression; microarrays; proteomics [does the polymorphism affect mRNA? in which tissues is the mRNA expressed? is there an effect on the protein product?]

Question 7

human genome

Answer 7

the complete DNA sequence in humans

Question 8

human proteome

Answer 8

the complete repertoire of proteins in humans

Question 9

size of haploid genome

Answer 9

3.3 billion bp

Question 10

what % of human genome is coding sequences?

Answer 10

about 3%

Question 11

how many protein-coding genes ?

Answer 11

around 21,000

Question 12

what % DNA sequence do two unrelated individuals share?

Answer 12

99.9% but can vary between two versions of the same chromosome