Hs 3320 Genetics

Front 1

What is heritability ?

Back 1

Heritability is the proportion of variation in a phenotype (trait, characteristic or physical feature) that is thought to be caused by genetic variation among individuals.

Front 2

What is Liability?

Back 2

refers to a genotype that a person is born with that predisposes them to genetic disease

Front 3

Twin Studies

Back 3

Twin studies :comparisons of identical (monozygotic) twins to fraternal or nonidentical (dizygotic) twins, are performed in order to estimate the relative contributions of genes and environment—that is, the extent to which environmental versus genetic influences operate on specific traits.

Front 4

Continuous Varaition

Back 4

The range of differences that can be observed in many characteristics in a population. Characteristics resulting from polygenic inheritance show continuous variation, e.g. the wide range of foot sizes in an adult human population.

Front 5

threshold

Back 5

the point at which the phenotypic change is expressed

Front 6

Hallamarks of Multifactorial Inheritance

Back 6

1.Most affected children have normal parents. This is true of diseases and quantitative traits.
2.Recurrence risk increases with the number of affected children in a family.
3.Recurrence risk increases with severity of the defect. A more severely affected parent is more likely to produce an affected child.
4.Consanguinity slightly increases the risk for an affected child.
5.Risk of affected relatives falls off very quickly with the degree of relationship. Contrast this with autosomal dominant inheritance with invomplete penetrance, where the recurrence risk falls off proportionately with the degree of relationship.
6.If the two sexes have a different probability of being affected, the least likely sex, if affected, is the most likely sex to produce an affected offspring.

Front 7

risk

Back 7

the chance of developing a phenotype