Sex Linked Disorders and Mitochondrial Inheritance Flashcards
How do you recognise an X-linked disorder from a pedigree
More than 1 generation
Usually only males affected
No male to male transmission
Why is there no male to male transmission
Dad gives Y to son
What does hemizygous mean
Disorder that only affects males
Why do some females show X-linked recessive traits
X-inactivation
Clonal and random
Lead to condensation of chromosome = bar body
XIST gene = expressed from inactive X to maintain silenced state
What would lead to cell death in terms of translocation involving x chromosome and autosome
If autosomal segment is on the X chromosome that is inactivated
What is the pedigree for X-linked dominant disease
Similar to autosomal dominant
XS females affected
No male to male transmission
What is the pedigree for Y linked inheritance
Only males affected
Affected males pass to all sons but no daughters
What is sex influence
When autosomal traits expressed more in one sex than another.
What is sex limitation
Appearance of certain features in individuals of only one sex
How is mitochondrial inheritance inherited
Maternal inheritance
What is heteroplasmy
If mutations arise, it will create mixed population of mitochondria in cell
What is replicative segregation
When cells divide, mitochondria partioned at random.
A certain amount of mutant mitochondria needed to express phenotype
Why is pedigree of mitochondrial inheritance hard to predict
Replicative segregation
Why can we not identify mutation in mitochondrial genes in some mitochondrial inherited disorders
Mutation can be a nuclear genes that is transported to mitochondria
How do you investigate Duchenne Muscular Dystrophy
High levels of Ck
Absence of staining with Abs to dystrophin
Deletions/mutations in dystrophin gene
