Genetics and Aging


THERE’S A FAMOUS QUOTE
FROM OLIVER WENDELL HOLMES WHICH IS THAT IF YOU WANT
TO LIVE A LONG LIFE, THE BEST THING TO DO IS GO OUT AND ADVERTISE FOR
SOME LONG LIVED PARENTS. THE REASON FOR THAT,
OF COURSE, IS THAT AGING AND DYING LIKE MANY ASPECTS OF
OUR HEALTH ARE AT LEAST PARTLY CONTROLLED BY OUR GENES. PEOPLE THAT HAVE LONG-LIVED
PARENTS ARE MORE LIKELY TO LIVE A LONG LIFE. THERE’S MANY REASONS FOR THAT
JUST AS THERE ARE MANY REASONS FOR DYING. GENES THAT PREDISPOSE A
PERSON TOWARDS CANCER, TOWARDS HEART DISEASE, TOWARDS
ANY OF THE NUMEROUS DIFFERENT PROBLEMS THAT PEOPLE HAVE
AS THEY AGE LIKE ALZHEIMER’S DISEASE, OF COURSE,
ARE MORE LIKELY TO DIE EARLY AND PEOPLE WITHOUT THOSE GENES
ARE MORE LIKELY TO DIE LATE. SO OBVIOUSLY AGING IS A COMPLEX
THING BUT GENES DO PLAY A ROLE. I THINK THE BIGGEST DEVELOPMENT
IN THE GENETICS OF AGING IS THE DISCOVERY OF SPECIFIC GENES
THAT ARE INVOLVED IN SOME OF THE WORST PROBLEMS
ASSOCIATED WITH AGING. FOR EXAMPLE,
ALZHEIMER’S DISEASE. ALZHEIMER’S
DISEASE IS VERY COMMON. WE USED TO THINK THAT PEOPLE
JUST GOT DOTTY AS THEY GREW OLD BUT WE NOW UNDERSTAND THAT
THERE’S A SPECIFIC DISEASE WITH A SPECIFIC SORT OF BRAIN
CHEMISTRY INVOLVED IN A FORMATION OF TANGLES AND
OTHER PROBLEMS IN THE NEURONS OF THE BRAIN. AND WE NOW KNOW THAT
THERE IS, AT LEAST IN PART, A GENETIC BASIS FOR ALZHEIMER’S
DISEASE AND SEVERAL OF THE DIFFERENT
GENES HAVE BEEN IDENTIFIED. SOME OF THESE GENES CAUSE A
VERY EARLY FORM OF ALZHEIMER’S. EVERY ONCE IN A WHILE A
PERSON WILL GET ALZHEIMER’S WHEN THEY’RE AT 40 OR 50 YEARS
OLD. AND THAT’S BECAUSE A DEFECT IN
A GENE THAT DIRECTLY CODES FOR SOME OF THE PROTEINS THAT GET
TOSSED UP INTO THESE TANGLES. OTHERS OF THE GENES LIKE THE
ONE FOR APOE E ARE MORE GENERIC AND THEY DON’T DETERMINE WHETHER
YOU GET ALZHEIMER’S BUT RATHER WHEN YOU’RE MOST LIKELY TO GET
IT. SO PEOPLE WITH THE APOE E, FOR
EXAMPLE, MAY BE MORE LIKELY TO GET
ALZHEIMER’S BY THE AGE OF 70. PEOPLE WITHOUT THAT FORM ARE
MORE LIKELY TO GET ALZHEIMER’S ONLY IF THEY GROW MUCH
OLDER, SAY INTO THEIR 90’S. THIS IS A REAL EXAMPLE
OF A PREDISPOSING FACTOR. DOESN’T TELL YOU WHETHER YOU’RE
GOING TO GET ALZHEIMER’S BUT WHAT YOUR LIKELIHOOD
IS AT DIFFERENT AGES.

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