Lecture 3: Clinical Applications of DNA Technology Flashcards
What is the best way to describe the mode of inheritance for Fragile X syndrome
X-linked dominance with reduced penetration
Where does the risk for a full mutation for Fragile X come from (who had the premutation?)
carrier mother
premutation grandfather
Which restriction enzyme - EagI or EcoR1 - only cuts unmethylated DNA?
EagI
On a southern blot of an X chromosome from a normal male: if digested with EagI-EcoR1, what size kb fragment, and how many fragments, will there be? Is this fragment methylated?
1x 2.8kb fragment
Not methylated - active X chromosome
On a southern blot of the X chromosomes from a normal female: if digested with EagI-EcoR1, what size kb fragment, and how many fragments, will there be? Will they be methylated?
1x 2.8kb fragment - unmethylated (active xs)
1x 5.2kb fragment - methylated (inactive xs)
In a full fragile X mutation, how many repeats are present, and of of what sequence?
CGG>200
How many bands will be seen on a Southern blot of a premutation female for fragile X after EagI-EcoR1 digest?
4 bands
2 normal, 2 premutation
both methylated and unmethylated
What two cellular conditions result from CGG>200 repeats?
abnormal methylation
mitotically unstable
What are hemoglobinopathies?
mutations in the alpha or beta globin chain genes
What do alpha and beta globin chains do?
Complex together with heme to carry O2 in the blood
What are thalassemias?
Mutations in globin chain genes that cause an imbalance of QUANTITY of the alpha and beta chains
What is the result of a sickle cell mutation?
Structural changes (QUALITY) in the beta globin gene
Which restriction sites does the sickle cell mutation affect?
Mnl I
Dde I
What kind of gene mutations occur in beta thalassemia?
point mutations in beta globin gene
Why isn’t beta thalassemia detected before birth?
have gamma globin before birth
beta globin comes in after birth
