Your Partental History? Whats Your Story??

[house]

Parental history...........

Am sure everyone who suffers from Keratoconus would like to
know why we have it? am sure this topic has been posted before??

obviously there's a genetic link and everyone has different contributory
factors?? that make us possibly have it??

Academics and researchers have talked about Parental history.

Whats Parental History?

A factor in your parents history or grandparents history that's passed
along the chain that makes you more likely to develop Keratonconus?

Am interested in this theory because it may be right for me??

My father suffered enforced malnutrition and ended up losing
all his teeth at 18 ( losing teeth at 18 shows the extend of the malnutrition)
and all my family have worn glasses for long as glasses where around!!!!!!!!!

100% had a major impact on him.

and there's poor vision in the family for a start.

Did his experience get passed to me?? and did it genetically make the odds of getting Keratoconus much higher for me??

Some people believe that this is a major factor, and some
how we do inherit 'life factors' from our parents??

Obviously there are other factors, but its very interesting!

I would say there are possible diffrent factors affecting people
in diffrents ways.

But it would be interesting to know your parential history??

The above is a theory so don't get to excited!!!!!!!!!!!!

[GarethB]

I was invited by a r srearcher from Leed University to attend a presentation she was giving and it confirms some of the research done my Moorfields. KC is genetic but due to the coming together of several recessive genes which is why in some ethnic groups it appears with no history of the condition in anyone else. Other groups such as the Asian and african communities KC has been observed to be more common.

Some of the research implies that if you do have these recessive genes you may still escape KC. This is from studies of identical twins, why does one have svere KC and it is only mild in the other when they are geneticaly the same?

For me one of the most sensible answers given to date is that genetics may mean you have a predisposition to the condition but there is something else that triggers it.

Take cancer for example, my grandad smoked a pipe and cigars from the age of 11 until he died in his eighties and never suffered cancer. My mum on the other hand never smoked, had a healthy lifestyle and was the first in her familly to suffer cancer. We concluded my mum had a predispotion to cancer and the smoking from my grandfather was probably the trigger. Grandad with no predisposition to cancer lived a very full and happy life.

I am the first person in my familly to have KC, others have had vision problems later in life with th exception of my brother who needs glasses and has worn them since his teens. No one has suggested he has KC (pre-clinical or otehrwise) and so far is has refused topography. I can understand why just incase he has preclinical KC and why should he if he gets perfect vision with glasses. Why fix what aint broke?

[Andrew MacLean]

Why is it obvious that there is a genetic factor in KC? Certainly there is strong suggestive anecdotal evidence, but I am not sure that this makes a genetic factor obvious.

So far as I am aware, I am the first person on either side of my family (maternal/paternal descent) to have keratoconus. My father, his father and all his brothers and sisters, his grandfather and all his brothers and sisters all lived to be a great old age, and none of them had keratoconus.

My father's sister did have glaucoma.

My mother, her sisters and their parents also lived to a reasonably old age, and again there was no keratoconus apparent in them.

Now, here is a problem; sometimes people will respond to this kind of history by saying, "your forebears must have had sub-clinical keratoconus."

Science progresses by the formulation of hypotheses, an examination of the hypothesis to determine what would count as evidence that the hypothesis is NOT true, then the formulation of experiments in the lab or in the real world that might disprove the theory.

If the theory is not disproved, then the hypothesis survives.

What would count as evidence that a theory of a universal genetic co-factor in keratoconus is not true? Well, somebody with a family history like mine where there has been no previous KC. To 'explain away' my family history is to make the theory unscientific and of little more value than one of Rudyard Kipling's just so stories.

Having said all of the above, let me also say one more thing: my son has keratoconus,so it is clear that my having it did not render him immune to it. My own hope is that some researchers will spend time looking for environmental co-factors so that we can develop strategies to prevent the emergence of KC in people, and avoid casting ourselves in the role of hapless victims of a random gene pool.

Andrew

ps I rather like 'how the camel got its hump' http://www.boop.org/jan/justso/camel.htm

pps I have just realized that Gareth and I were posting at the same time. I like the notion of recessive genes combining to produce a predisposition to KC, because it leaves open the far more interesting question of how we can adopt strategies to prevent or obviate the condition.

I have always thought that identical twin studies are inadequate; they do present two individuals who are genetically identical, but it is hard to control for other variants: apart from a very few known cases it is hard to control for the similar environmental exposure of identical twins.

[house]

I dont know if you missed the point that your parents life experinces are a factor too?
and possible your grand parents? and thats passed on........
some how!!

[GarethB]

Found some notes I had taken from an AGM a few years back and current thinking is that about 5 genes are involved with KC.

We are made up of 23 pairs of chromosomes which totals between 20,000 and 25,000 genes, so for 5 specific recessive genes to come together out of that lot are very small hence KC being so rare.

Grandparents and parents life experiences being a factor I personally feel is unlikly unless it causes damage to certain genes in the reproductive system. Smokeing or exposure to toxic chemicals for example are known to damage DNA.

Diagnostic techneques are more adavnce, I have KC and it's been suggested my wife is sub-clinical and fortunatly my daughter shows no signs of KC, we have all had topographies done now, my daughter being the first to have a baseline. We are probably the first generation to have such information to share with our children, grandchildren and great grandchildren.

[Andrew MacLean]

House,

Although you may have already gathered that Gareth and I are not as one on the question of genetic predispositions to KC, I do agree with him that it is hard to see how environmental factors that do not damage DNA can have an effect on successive generations.

There are, however, environmental factors that may have an influence across the generations: the quantity of salt in the diet is one obvious possible co-factor. This also has a cultural dimension, as different cultures have different patterns of sodium consumption.

Andrew

[rosemary johnson]

To quote a very very old saying about the difference between genetic and environmental factors.....
If life experiences of the parents could be passed on as genetic traits to the children, grandchildren, etc, then there would long have been no more need for Jewish families to circumcise their baby boys.
No, seriously... think about it.....
It is possible that severe malnutrition in one's youth could cause enough stress to one's reporductive system as to result in genetic defects in one's babies. But I'd have thought it would give problems conceiving at all before genetic defects in the offspring. And if it did result in genetic defects, why would damage to a parent's reproductive system that left them producing gametes with damaged DNA, why would there be a recognisable condition like KC produced, rather than physical malformities evident from birth?
Certainly there may be environmental factors that can serve as triggers which may run through several generations of the same family - whether that's diet, or behaviour patterns - or having parents who are terribly concerns for their kids to do well at school and will rush them off to the doctor's, optician's or hospital at the first sign they can't read their school books or the schoolroom blackboard as well as might be expected.
I suspect that before the days of compulsory schooling, and for people working in occupations that didin'tned a lot of close work, there were probably many people with undiagnosed eye conditions, whether KC or just a it shortsightedness. I mean, if you're spending your life out int he fields looking after cows, or digging canals, you could probably get away with more dodgy eyesight than people who sit in front of computers much f their time nowadays.
The idea that KC was a genetic predisposition and a trigger factor to set it off has been around for a while. And the idea of needing several genes to come together makes sense too.
About twin studies - if the twins have grown up together, then you could not tell how much of an identifcal outcome came from genetics and how much from lifestyle. I think the key thing with twins and KC is that they DON'T all come out alike - you can have identical twins, so same genes, grown up together so very similar nuture, an done has KC and the other doesn't. Or one much worse than the other. Something is causing the difference.....
In my family, we have lots of people who've worn glasses. ON my mum's side of the family, there are/were lots of people with astigmatism (my mum's is quite pronounced and I'm sure my sister will chip in for herself here - she has glasses and astigmatism but not KC).
On my father's side of the family, we have autoimmune diseases.
One theory I've heard was the possibility that one trigger factor could be an autoimmune type reaction.
Well, I have KC, and I also have hay fever, asthma, allergies, swell up ike a football from some types of insect bite...... and am developing more hypersensitivity reactions all the time, alas.
Two of the gene strands coming together here??!
Rosmeary

[Barbara Davis]

Rosemary wrote:

If life experiences of the parents could be passed on as genetic traits to the children, grandchildren, etc, then there would long have been no more need for Jewish families to circumcise their baby boys.


Barbara:

Or to put it another way,

"There's a divinity that shapes our ends,
Rough-hew them how we will."

Hamlet