p53
Forum Guru
Topics: 51
Posts: 804
|
'Mitochondrial mutations causing Leber's neuropathy are inherited from the mother by all her children, but usually only sons develop symptoms.'
Why?
___________________
"Everything should be made as simple as possible, but not simpler." - Albert Einstein
|
| marasmus
Forum Junior
Topics: 2
Posts: 42
|
coz' the mitochondria are principally in the egg...less so in the sperm..if my memory serves me right
|
| marasmus
Forum Junior
Topics: 2
Posts: 42
|
not sure why only sons develop symptoms though
|
| an
Forum Guru
Topics: 19
Posts: 437
|
nice qu p53...i dont know the answer though..this is what i found from different sources...
"it has been seen that LHON has a very high level of variability causing complete blindness in some and minor vision loss in others, and predominance in males(male to female ratio being 3.7 to 7.7:1 depending on different mutations). The variability could be due to percentage of defective mitochondria carried by individual cell. The male predominance is hypothesized as there being X-linked loci that influence the penetrance."
___________________
I don't believe in miracles...I rely on them. And sometimes, I create my own.
|
| p53
Forum Guru
Topics: 51
Posts: 804
|
thank you, an, your quote is very helpful - so, for LHON to develop someone has to have 1. wrong mitochondria from her mother and 2. only one X chromosome - but I'm still confused why these X-linked loci aren't working (or are working, if they are doing good job) if a person has 2 X chromosomes, i.e. is female. Can we extrapolate explanation for other X-linked disorders (i.e. females are free of disease because of random mosaic X inactivation) to LHON? then it means that some X chromosomes are wrong and others aren't - but I doubt this could be in case here - what do you think?
Edited by p53 on 04/08/06 - 07:23 PM
___________________
"Everything should be made as simple as possible, but not simpler." - Albert Einstein
|
| an
Forum Guru
Topics: 19
Posts: 437
|
what u r saying is correct...
of the mitochondrial mutation carriers, 50% males get affected and 10% females get affected...so, 2 things r required for penetrance, the responsible mitochondrial gene, and another X-linked factor(probably recessive)..so females are probably heterozygous at the X-linked locus, and r affected, like u said, by random X-inactivation.
but so far, no study has identified this X-linked locus
___________________
I don't believe in miracles...I rely on them. And sometimes, I create my own.
|
| p53
Forum Guru
Topics: 51
Posts: 804
|
thanks, an.
nice avatar, by the way.
___________________
"Everything should be made as simple as possible, but not simpler." - Albert Einstein
|
|
| |
| | | | | | | |
