genetic / hereditary / congenital

[englishstudent]

Hi,

is it possible to use the words "genetic" and
"hereditary" interchangeably when refering
to a disease/illness? Or is the distinction
here that "genetic" is an illness due to
genes predisposed to an illness (but the parents
or grandparents may not have that illness), and
"hereditary" is if it has been inherited from
parents/grandparents?

If a person is born with an illness, then it
is "congenital", and thus automatically
"genetic" and "hereditary" if the parents
or ancestors had the same illness, right?

Thanks

[MikeNewYork]

Hi,

is it possible to use the words "genetic" and
"hereditary" interchangeably when refering
to a disease/illness? Or is the distinction
here that "genetic" is an illness due to
genes predisposed to an illness (but the parents
or grandparents may not have that illness), and
"hereditary" is if it has been inherited from
parents/grandparents?

If a person is born with an illness, then it
is "congenital", and thus automatically
"genetic" and "hereditary" if the parents
or ancestors had the same illness, right?

Thanks

In answer to your first question, all hereditary diseases are genetic, but not all genetic diseases are hereditary. Some genetic diseases are caused by mutations, errors, chemicals, etc., independent of the gene structure of the parents.

The second question is more difficult and depends on the definition of congenital. If a baby is born with a defect that has occurred in the baby's ancestors at a rate higher than in the normal population, it is likely to be genetic and inheritable. But it also could be caused by toxins in the environment, such conditions possibly being available to the baby's ancestors as well. Some diseases appear to be congenital, but are actually caused by infectious organisms. Biliary atresia in children had been considered a congenital, genetic defect for many decades. Then it was discovered that these fetuses had been infected by a virus that caused the problem. Other congenital diseases may not be recognized as such because they don't reveal themselves for many years after birth. Lyme disease in young children was considered to be a genetic disease until a persistent mother bugged Yale Medical Center until they discovered the organism.

[englishstudent]

In answer to your first question, all hereditary diseases are genetic, but not all genetic diseases are hereditary. Some genetic diseases are caused by mutations, errors, chemicals, etc., independent of the gene structure of the parents.

OK. Thanks. I was looking for some clear statement like this (all hereditary diseases are genetic, but not all genetic disease are hereditary) to help
me understand it.

If a baby is born with a defect that has occurred in the baby's ancestors at a rate higher than in the normal population, it is likely to be genetic and inheritable. But it also could be caused by toxins in the environment, such conditions possibly being available to the baby's ancestors as well.

I now understand what you said about how what appears as a congenital disease may actually be caused by viruses. I just want to seek
clarification on the last sentences above to make sure I understand
it properly. If two people are exposed to similar conditions (be it
toxic enviroment, or sedentary habits, or diet poor in nutrition), and
if one person develops a problem but not the person, it could be
because his/her genes are predisposed to react that way
(ie to create a state of disease). In that case it can be called
"genetic disease", right?

I still have some confusion about "hereditary". If a person has a diease
that his great grandparents had, but not his parents or grandparents,
then is it still "hereditary", even though the person is not inheriting
it directly from his parents? Or would that be called "genetic"?
Sorry, if my question is not clear. I am not able to think clearly.
Part of my confusion arises from thinking about the word "inherited"
or "inheritance" in the context of wealth/property.
In case of wealth, a person inherits it from his/her
parents, although it is conceivable in some cases that he/she
got the wealth directly from the grandparents. But in case of a
disease, it may somehow not effect the intermediate generations.

[MikeNewYork]

OK. Thanks. I was looking for some clear statement like this (all hereditary diseases are genetic, but not all genetic disease are hereditary) to help
me understand it.



I now understand what you said about how what appears as a congenital disease may actually be caused by viruses. I just want to seek
clarification on the last sentences above to make sure I understand
it properly. If two people are exposed to similar conditions (be it
toxic enviroment, or sedentary habits, or diet poor in nutrition), and
if one person develops a problem but not the person, it could be
because his/her genes are predisposed to react that way
(ie to create a state of disease). In that case it can be called
"genetic disease", right?

Not necessarily. A genetic tendency or predisposition is probably not enogh to be called a disease. For example. A person might develop colon cancer in his/her 30s or 40s. If that has been a pattern in his her family, I would say they have a genetic disease of sorts. However, if the colon cancer develops in the person's 70s or 80s, I would not call that a genetic disease even if his entire family died of colon cancer in their 70s and 80s. We all have to die from something.

I still have some confusion about "hereditary". If a person has a diease
that his great grandparents had, but not his parents or grandparents,
then is it still "hereditary", even though the person is not inheriting
it directly from his parents? Or would that be called "genetic"?
Sorry, if my question is not clear. I am not able to think clearly.
Part of my confusion arises from thinking about the word "inherited"
or "inheritance" in the context of wealth/property.
In case of wealth, a person inherits it from his/her
parents, although it is conceivable in some cases that he/she
got the wealth directly from the grandparents. But in case of a
disease, it may somehow not effect the intermediate generations.

Some inheritable genetic problems are known to skip generations. In addition, many defects caused by recessive genes will show up only when both genes are recessive. Consider this: (dominant genes are capitals, recessive are lower case):

great-grandparents: xx + Xx (one sick)

grandparents: Xx + Xx (nobody sick)

parents: Xx + Xx (nobody sick)

children xx , Xx, and XX (one sick)

[englishstudent]

Regarding the first part, even though it is true that we
all have to die of something, strictly speaking (ie by the definition of - all
hereditary diseases are genetic, but not all genetic diseases are hereditary), I would have thought it is called a "genetic disease" because the parents and possibly grandparents also
had the same disease.

Regarding the second part, I would have to read up a bit about genetics
to understand what you have written above. :)

Thank you for clarifying.

[MikeNewYork]

Regarding the first part, even though it is true that we
all have to die of something, strictly speaking (ie by the definition of - all
hereditary diseases are genetic, but not all genetic diseases are hereditary), I would have thought it is called a "genetic disease" because the parents and possibly grandparents also
had the same disease.

Regarding the second part, I would have to read up a bit about genetics
to understand what you have written above. :)

Thank you for clarifying.

My point is that if any slight predisposition is a genetic disease then everyone on the planet has one. That concept loses meaning when expanded too far.

Sorry about the diagrams. When looking at inheritance schemes, keep in mind that each parent gives one of a pair of genes to each offspring. In simple genetic traits (one set of genes) a parent with XX can only give X, a parent with xx can only give x. A parent with Xx can give either.

[englishstudent]

My point is that if any slight predisposition is a genetic disease then everyone on the planet has one.

True. I remember reading something like this (not verbatim) -
"Life is a sexually transmitted incurable disease."

Sorry about the diagrams. When looking at inheritance schemes, keep in mind that each parent gives one of a pair of genes to each offspring. In simple genetic traits (one set of genes) a parent with XX can only give X, a parent with xx can only give x. A parent with Xx can give either.

No, I am just not up to speed on this, and whatever I read a while
ago, I have already forgotten. But after reading your response
it jogged my memory about each parent giving one of a pair.

Thanks.

[MikeNewYork]

It is an incurable state, at any rate.