Posted by gary (208.133.220.133) on January 03, 19100 at 11:49:33:
In Reply to: Genetic link posted by Joe Stone on January 03, 19100 at 10:18:38:
REAL good contribution Joe
and excellent insight on just how many family members it takes for CH to visibly repeat
the further we go in putting the pieces on the puzzle board, the more the impact of a preexisting physical susceptability - either from genetic determination or some sort of structural defect appears to be at the very root of CH
I've got 2 close family members who are geneticists by training and occupation, one a recent grad working in commercial pharmacological biochemistry and one an experienced research associate at one of the bigger Univ. med schools, and I nailed 'em good over the holidays - backed 'em into corners & wouldn't let 'em at the shrimp and eggnog till they made with the info -
best guess we're coming up with is this CH requires a combination of specific traits,
an extremely polygenetic situation,
each of which is the result of an unlikely pairing, so to get them all lined up suitable for CH isn't going to happen predictably in the small population that a couple generations of one family provides
common guesstimates of CH occurence seem to center on 1/2 - 1 % of the general population;
consider: working backwards, it takes 6 generations to come up with 100 people to make an individual 1% of the pool - you count everybody in the chain, because each is a different catalog of pairings, so it;s 2+4+8+16,etc ) -
now that's pretty simplistic, but it has as much validity as it is challengable, so don't pick on the fine points because we're talking generality anyway
at even double the apparent CH rate, it would take 5 generations.......
would mean for example that given all your antecedents back thru your great-great-great-grandparents, it would require only 1 or 2 other CH patients to exceed the random occurence to begin with
I happen to personally think there is a region-of-origin factor in WHO carries the potential, related to evolved responses to annual light cycles, but it's a pretty wide category and would probably only alter the randomness by a couple factors at most - STILL leaving a very large pool required for each case
there is NO way ANYBODY has that good a catalog of their family tree for SURE, much less the medical profiles SO -
as a way to avoid facing the fact we don't know a damned thing really (ain't that right Drum !?!),
in popular usage, we tend to only look at what we do know - the last couple generations - when talking about inherited characteristics
Drs usually only take medical history back to grandparents - that doesn't mean what went before is irrelevant - it just means the docs don't ask about it !!!!!
and pretty much comes form earlier understandings of genetics, when they thought any characteristic was presented by a simple majority influence in the ancestry,
eg: 5/8 parts meant you had it, 3/8 meant you wouldn't - that of course has long since been shown to be a very small part of the puzzle, but things take a LONG LONG time to grow into common knowledge, and until they do the old view is fiercely defended -
usually by those who are threatened by the new because they can't or won't keep up, for whatever reason
and, in the case of CH - even if it IS an inherited trait, it is drawn from way too large an ancestor pool to obviously document in the individual case -
and THAT in turn "disqualifies" it as a genetic problem in the unimaginative and simplistic mind
THAT in turn fuels a LOT of the refusal of people to understand/learn what this is all about
and again, like the discussion thread coming from Angela's recent post,
it seems that if we need to have somebody understand this to feel OK - we'd better just work harder at having it be the person in our mirror that understands it better !
SO -
maybe one simple way to put it is something like:
CH is most likely based on inherited susceptability, but is so rare and requires such a specific combination of genetic alignments, that repeat occurrence in very close family relationship is probably just a freaky random event, as if two unrelated neighbors discovered they each had this rare malady....
there's even a parallel to the Y2K fiasco in all of this-
paranoia over the size and import of Y2K potential problems seemed to be in inverse proportion to how technology literate people were -
the more folks knew about computers and how things really work, the LESS they were concerned-
it was the people who didn't have a clue that were running around looking for the sky to fall
and it is ever thus
to keep the CH sky from falling in on you -
don't look for magic pills or somebody to fix it for you-
LEARN about it-
THAT and ONLY that can take away the fear and insecurity,
and once you've got a handle on that the problem reduces dramatically
I Guarandamtee You!
(and I wish to hell I had followed my instincts and bought a bunch of internet/computer/electronic stock last week, just before new years - - it's ROARING today -- probably the biggest Y2K reaction we'll see)