Sex Linked Disorders and Mitochondrial Inheritance Flashcards Preview

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Flashcards in Sex Linked Disorders and Mitochondrial Inheritance Deck (18):
1

How do you recognise an X-linked disorder from a pedigree

More than 1 generation
Usually only males affected
No male to male transmission

2

Why is there no male to male transmission

Dad gives Y to son

3

What does hemizygous mean

Disorder that only affects males

4

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

5

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

6

What is the pedigree for X-linked dominant disease

Similar to autosomal dominant
XS females affected
No male to male transmission

7

What is the pedigree for Y linked inheritance

Only males affected
Affected males pass to all sons but no daughters

8

What is sex influence

When autosomal traits expressed more in one sex than another.

9

What is sex limitation

Appearance of certain features in individuals of only one sex

10

How is mitochondrial inheritance inherited

Maternal inheritance

11

What is heteroplasmy

If mutations arise, it will create mixed population of mitochondria in cell

12

What is replicative segregation

When cells divide, mitochondria partioned at random.
A certain amount of mutant mitochondria needed to express phenotype

13

Why is pedigree of mitochondrial inheritance hard to predict

Replicative segregation

14

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

15

How do you investigate Duchenne Muscular Dystrophy

High levels of Ck
Absence of staining with Abs to dystrophin
Deletions/mutations in dystrophin gene

16

What would an in frame protein result in

Becker Muscular Dystrophy
Only one aa missing. No shift in frame

17

What would an out of frame protein result in

DMD
Deletion of bases so that downstream sequence affected
Rubbish protein often truncated

18

What are some of the signs of DMD

Infant with Gower's sign
Calf pseudohypertrophy
Intellectual impairment
Progressive weakness