you or someone in your family has Type 2 diabetes,
you may wonder if other family members are at risk.
It turns out that Type 2 diabetes often runs in families
and is also more common in some ethnic groups. In fact,
researchers have found many genes
that can effect your heritable risk for developing Type
researchers know from studying family histories that
you can inherit a risk for Type 2 diabetes, they have
had difficulty identifying specific gene mutations
that cause the disease.
of the problems include:
these problems, researchers have found a few gene mutations
that influence diabetes risk in some families. One well
studied gene is the Beta3-adrenergic receptor gene. For
recent news about additional Type 2 diabetes genes, see
related news below.
Number of genes:
Many genes are involved in controlling our fuel intake
and regulation. A mutation in any one gene will probably
not lead to diabetes, but mutations in several genes
could add up to pose an increased risk. Any two people
with Type 2 diabetes may have mutations in a different
subset of genes, making it hard for researchers to
pinpoint high-risk mutations.
Environmental influence: A person's lifestyle
and environment play a large role in whether or not
they develop Type 2 diabetes. Two people may have
the same risk and the same gene mutations, but if
one person controls their weight and exercises regularly,
that person may not develop diabetes. If two people
have the same mutation but different outcomes, researchers
have a hard time distinguishing which genes are important
in the disease.
Lifestyle: We inherit more than just genes from
our parents; we also inherit lifestyle. Poor eating
habits and lack of exercise are learned behaviors
that children can pick up from their parents. This
type of inheritance has nothing to do with genes,
and makes it hard for researchers to identify a genetic
risk for diabetes.
Beta3-adrenergic receptor gene makes a protein
in fat cells that is involved in determining how much
fuel your body burns when you are resting. A mutation
in this gene slows down how quickly a person burns fat
increasing their tendency to be obese. One specific
mutation in this gene, called TRP64ARG, is almost four
times more common in Pima Indians than in people of
European descent, and is one and a half times more common
in people of African or Mexican descent. The prevalence
of the TRP64ARG gene mutation in these populations probably
accounts at least in part for why these ethnic groups
have a higher rate of Type 2 diabetes.
with two copies of the TRP64ARG mutation:
Have slower metabolism
Have a hard time losing weight
Develop diabetes at an earlier age
with two copies of the TRP64ARG mutation have a slower
metabolism than people without the
mutation. Therefore, they tend to be more obese
even in mutation carriers who do not go on to develop
diabetes. They also have a harder time losing weight
than the general population. In addition, people with
the TRP64ARG mutation develop diabetes at an earlier
age than Type 2 diabetics without the mutation. This
mutation is not present in all Type 2 diabetics, but
it appears to change the course of diabetes in those
who carry it.
The TRP64ARG mutation causes the Beta3-adrenergic receptor
gene to make a different protein sequence. The name
is an abbreviation for the change in the protein caused
by the mutation. The altered protein has the amino
acid Arginine (ARG) at the 64th position, rather
than the amino acid Tryptophan (TRP). This switch in
amino acid building blocks prevents the protein from
The Beta3-adrenergic receptor gene is not the only gene
that regulates how we metabolize fat. Researchers think
that mutations in similar genes may also put a person
at risk for diabetes. So far, they have not found common
mutations in these genes that cause diabetes, but there
is ongoing research in high-risk populations and families
to find additional gene mutations.
genetics of Type 2 diabetes is complicated, with many
different genes influencing a person's risk. Because
of this array of genes, Type 2 diabetes is not inherited
in a clearly dominant
manner. Instead, a person may have one gene that increases
their risk and other genes that decrease risk. Together,
these genes, along with environmental factors, determine
a person's overall risk for developing diabetes. With
so many variables to consider, the medical community
is a long way from a genetic test
for Type 2 diabetes.
there is no genetic test for Type 2 diabetes, the American
Diabetes Association recommends screening for diabetes
onset every three years if you have diabetes in the
family. Doctors screen for diabetes onset using a fasting
glucose test or glucose tolerance
test, which tells doctors if your blood glucose
levels are unusually high.
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diabetes mellitus and genetic variation in the B(3)-adrenergic
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