Unit 9 - 4 Genetics

Front 1

multifactorial disorders

Back 1

resulting from the combined deffects of multiple genes and the environment

Front 2

two sorts of multifactorial characters or traits

Back 2

continuous: trait you can measure (height,bp,iq)

discontinuous: can't measure (you either have it or you don't, either have diabetes or don't)

Front 3

basic model

Back 3

explains how to inherited a quantitative trait

Front 4

threeshold model

Back 4

theoretical model; cant measure trait; postualtes that suceptibility to the disease is a continuous character

Front 5

threshold model

Back 5

each person needs to be above the threshold of liability

if you have enough bad genes + environmental cues = liability = you will have the dz

ratio above threshold/area under curve = reflects incidence of the dz

Front 6

conseuences of the liability/threshold model on reuccrence risks

Back 6

the recurrence risk increases if the expression of the dz in the proband is more severe

more severe disease = higher recurrence risk

Front 7

threshold of liability and sex bias

Back 7

if threshold of liability is sex bias for a particular dz, the less frequently affected sex has a higher risk to transmit dz

distribution of the liability has a diff threshold for m/f (so if m has lower threshold = less liability to be affected)

Front 8

complex inheritance diseases

Back 8

cluster in family; familair clustering of a dz is measured by relative risk

Front 9

1/8

Back 9

first cousins

Front 10

uncles/aunt niece/nephew

Back 10

1/4

Front 11

half sibs

Back 11

1/4

Front 12

sibs

Back 12

1/2

Front 13

parent child

Back 13

1/2

Front 14

estimating heritability (h^2)

Back 14

h^2 = 2(Cmz - Cdz)

Front 15

alleles shared between identical twins

Back 15

100% or 1 (highest risk)

The important concept associated to these studies is that the more closely related individual are in a family, the more alleles they have in common

Front 16

alleles shared between parent-child

Back 16

1/2

The important concept associated to these studies is that the more closely related individual are in a family, the more alleles they have in common

Front 17

alleles shared between sibs

Back 17

1/2
The important concept associated to these studies is that the more closely related individual are in a family, the more alleles they have in common

Front 18

alleles shared between half sibs

Back 18

1/4
The important concept associated to these studies is that the more closely related individual are in a family, the more alleles they have in common

Front 19

alleles shared between uncle/aunt-niece/nephew

Back 19

1/4

The important concept associated to these studies is that the more closely related individual are in a family, the more alleles they have in common

Front 20

alleles shared between first cousins

Back 20

1/8 (least risk)

The important concept associated to these studies is that the more closely related individual are in a family, the more alleles they have in common

Front 21

concodrant

Back 21

When two individuals in a family have the same disease, they are said to be concordant for the disease.

Front 22

discordant

Back 22

When one member of the family is affected but the other member is not, these two relatives are discordant for the disease

Front 23

monozygotic twins with concordance rate <1

Back 23

Concordance rate 100% (or 1) strongly indicates that the disease is determined by genes.
Concordance rate less than 100% (or 1) disease can have a genetic component but non genetic factors play a role. Lower the rate, more prevalent is the contribution of non genetic factors.

Front 24

dizygotic twins with a concordance rate close to 50% or .5

Back 24

concordance rate would only be close to 50% (or 0.5) if the disease is determined by genes only.

less than 50% suggests genetic component