Chapter 7 - Patterns of Genetic Inheritance - Part 2
Preimplantation Genetic Diagnosis
If prospective parents carry an allele for a genetic disorder, they may seek assurance that
their offspring will be free of the disorder
Following in vitro fertilization (IVF), the zygote divides
When the embryo has 8 cells, 1 may be removed for genetic testing
Only embryos that will not have the genetic disorders of interest are placed in the uterus to
continue developing
1
,2
, Polygenic Inheritance
Polygenic traits: 2 or more sets of alleles govern 1 trait
Each dominant allele codes for a product, so these effects are additive.
This results in a continuous variation of phenotypes.
Environmental effects cause intervening phenotypes.
e.g., skin color ranges from very dark to very light
e.g., height varies among individual humans
Multifactorial trait: A polygenic trait that in addition to genetics are particularly influenced
by the environment
3
Preimplantation Genetic Diagnosis
If prospective parents carry an allele for a genetic disorder, they may seek assurance that
their offspring will be free of the disorder
Following in vitro fertilization (IVF), the zygote divides
When the embryo has 8 cells, 1 may be removed for genetic testing
Only embryos that will not have the genetic disorders of interest are placed in the uterus to
continue developing
1
,2
, Polygenic Inheritance
Polygenic traits: 2 or more sets of alleles govern 1 trait
Each dominant allele codes for a product, so these effects are additive.
This results in a continuous variation of phenotypes.
Environmental effects cause intervening phenotypes.
e.g., skin color ranges from very dark to very light
e.g., height varies among individual humans
Multifactorial trait: A polygenic trait that in addition to genetics are particularly influenced
by the environment
3
