Biochemistry - Multifactorial Inheritance

Front 1

what is a polygenic trait or disease?

Back 1

a trait or disease caused by the impact of many different genes, each with a limited impact on the phenotype

Front 2

what are multifactorlal diseases?

Back 2

diseases caused by the interplay of multiple genes and multiple evironmental factors

Front 3

are polygenic traits normally quantitative or qualitative in nature?

Back 3

quantitative

Front 4

what is the threshold model of multifactorial disease?

Back 4

a model which states that some proportion of individuals above a certain threshold of genetic liability will develop the disease, especially if exposed to environmental triggers

Front 5

does the risk for mutifactorial diseases increase or decrease if more than one family member is affected?

Back 5

increases

Front 6

is the risk for a multifactorial disease necessarily higher if the expression of the disease is more severe in the proband?

Back 6

yes

Front 7

is the risk for multifactorial disease greater or less for the sibling of a proband of the less commonly affected sex?

Back 7

greater

Front 8

is the recurrence risk for the disease higher in first-degree or second-degree relatives?

Back 8

much higher in first-degree relatives

Front 9

is the frequency of multifactorial diseases higher within a family than in the general population?

Back 9

yes, it is higher within related individuals

Front 10

how can twins be used to see if a disease is passed genetically or not?

Back 10

if a disease is entirely genetic, 100% monozygotic twin pairs should be concordant for the disease, while only 50% of dizygotic twin pairs will be concordant

Front 11

other than family and twins, what is another indication of the genetic nature of a disease?

Back 11

if the disease is rare and passed in a Mendelian fashion

Front 12

why has the identification of genetic factors in IDDM involved analysis of affected sib pairs in families?

Back 12

if 2 siblings are both affected by a genetic disease, we would expect to see increased sharing of marker genes in the genomic region that contains a susceptibility gene

Front 13

what percentage of their genes do siblings share, on average? What proportion of marker polymorphisms would you expect to not be linked to a susceptibilty locus in siblings?

Back 13

50%; 50%

Front 14

if siblings share the same alleles for a marker polymorphism around 75%, of what is this evidence?

Back 14

marker is linked to a susceptibility locus

Front 15

in animal models, how must a diseases individual be mated to perform linkage analysis?

Back 15

diseases bred with normal to produce F1 then F1 backcrossed with normal to produce F2. Linkage analysis performed on recombined disease chromosome of F2