What is familial adenomatous polyposis?<
/h2> Famil
ial adenomatous polyposis (FAP) is an inherited disorder characterized by c
ancer of the large intestine (colon) and rectum. People with the classic ty
pe of familial adenomatous polyposis may begin to develop multiple noncance
rous (benign) growths (polyps) in the colon as early as their teenage years
. Unless the colon is removed, these polyps will become malignant (cancerou
s). The average age at which an individual develops colon cancer in classic
familial adenomatous polyposis is 39 years. Some people have a variant of
the disorder, called attenuated familial adenomatous polyposis, in which po
lyp growth is delayed. The average age of colorectal cancer onset for atten
uated familial adenomatous polyposis is 55 years.
In people with classic familial adenoma
tous polyposis, the number of polyps increases with age, and hundreds to th
ousands of polyps can develop in the colon. Also of particular significance
are noncancerous growths called desmoid tumors. These fibrous tumors usual
ly occur in the tissue covering the intestines and may be provoked by surge
ry to remove the colon. Desmoid tumors tend to recur after they are surgica
lly removed. In both classic familial adenomatous polyposis and its attenua
ted variant, benign and malignant tumors are sometimes found in other place
s in the body, including the duodenum (a section of the small intestine), s
tomach, bones, skin, and other tissues. People who have colon polyps as wel
l as growths outside the colon are sometimes described as having Gardner sy
ndrome.
A mild
er type of familial adenomatous polyposis, called autosomal recessive famil
ial adenomatous polyposis, has also been identified. People with the autoso
mal recessive type of this disorder have fewer polyps than those with the c
lassic type. Fewer than 100 polyps typically develop, rather than hundreds
or thousands. The autosomal recessive type of this disorder is caused by mu
tations in a different gene than the classic and attenuated types of famili
al adenomatous polyposis.
How common is familial adenomatous polyposis
?
The
reported incidence of familial adenomatous polyposis varies from 1 in 7,00
0 to 1 in 22,000 individuals.
What genes are related to familial adenomatou
s polyposis?
Mutations in the APC gene cause both classic and attenuated familial adenomatous po
lyposis. These mutations affect the ability of the cell to maintain normal
growth and function. Cell overgrowth resulting from mutations in the APC gene leads to the
colon polyps seen in familial adenomatous polyposis. Although most people w
ith mutations in the AP
C gene will develop colorectal cancer, the number of polyps and the
time frame in which they become malignant depend on the location of the mut
ation in the gene.
Mutations in the M
UTYH gene cause autosomal recessive familial adenomatous polyposis (
also called MYH-associated polyposis). Mutations in this gene prevent cells
from correcting mistakes that are made when DNA is copied (DNA replication
) in preparation for cell division. As these mistakes build up in a person'
s DNA, the likelihood of cell overgrowth increases, leading to colon polyps
and the possibility of colon cancer.
How do
people inherit familial adenomatous polyposis?
Familial adenomatous polyposis ca
n have different inheritance patterns.
When familial adenomatous polyposis results from m
utations in the APC gene, it is inherited in an autosomal dominant pattern, which means one
copy of the altered gene in each cell is sufficient to cause the disorder.
In most cases, an affected person has one parent with the condition.
When familial adeno
matous polyposis results from mutations in the MUTYH gene, it is inherited in an autosomal
recessive pattern, which means both copies of the gene in each cell have mu
tations. Most often, the parents of an individual with an autosomal recessi
ve condition each carry one copy of the mutated gene, but do not show signs
and symptoms of the condition.
Famil ial adenomatous polyposis (FAP) is an inherited disorder characterized by c ancer of the large intestine (colon) and rectum. People with the classic ty pe of familial adenomatous polyposis may begin to develop multiple noncance rous (benign) growths (polyps) in the colon as early as their teenage years . Unless the colon is removed, these polyps will become malignant (cancerou s). The average age at which an individual develops colon cancer in classic familial adenomatous polyposis is 39 years. Some people have a variant of the disorder, called attenuated familial adenomatous polyposis, in which po lyp growth is delayed. The average age of colorectal cancer onset for atten uated familial adenomatous polyposis is 55 years.
In people with classic familial adenoma tous polyposis, the number of polyps increases with age, and hundreds to th ousands of polyps can develop in the colon. Also of particular significance are noncancerous growths called desmoid tumors. These fibrous tumors usual ly occur in the tissue covering the intestines and may be provoked by surge ry to remove the colon. Desmoid tumors tend to recur after they are surgica lly removed. In both classic familial adenomatous polyposis and its attenua ted variant, benign and malignant tumors are sometimes found in other place s in the body, including the duodenum (a section of the small intestine), s tomach, bones, skin, and other tissues. People who have colon polyps as wel l as growths outside the colon are sometimes described as having Gardner sy ndrome.
A mild er type of familial adenomatous polyposis, called autosomal recessive famil ial adenomatous polyposis, has also been identified. People with the autoso mal recessive type of this disorder have fewer polyps than those with the c lassic type. Fewer than 100 polyps typically develop, rather than hundreds or thousands. The autosomal recessive type of this disorder is caused by mu tations in a different gene than the classic and attenuated types of famili al adenomatous polyposis.
The reported incidence of familial adenomatous polyposis varies from 1 in 7,00 0 to 1 in 22,000 individuals.
Mutations in the APC gene cause both classic and attenuated familial adenomatous po lyposis. These mutations affect the ability of the cell to maintain normal growth and function. Cell overgrowth resulting from mutations in the APC gene leads to the colon polyps seen in familial adenomatous polyposis. Although most people w ith mutations in the AP C gene will develop colorectal cancer, the number of polyps and the time frame in which they become malignant depend on the location of the mut ation in the gene.
Mutations in the M UTYH gene cause autosomal recessive familial adenomatous polyposis ( also called MYH-associated polyposis). Mutations in this gene prevent cells from correcting mistakes that are made when DNA is copied (DNA replication ) in preparation for cell division. As these mistakes build up in a person' s DNA, the likelihood of cell overgrowth increases, leading to colon polyps and the possibility of colon cancer.
Familial adenomatous polyposis ca n have different inheritance patterns.
When familial adenomatous polyposis results from m utations in the APC gene, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.
When familial adeno matous polyposis results from mutations in the MUTYH gene, it is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mu tations. Most often, the parents of an individual with an autosomal recessi ve condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.
What is familial adenomatous polyposis?
Familial adenomato us polyposis (FAP) is an inherited disorder characterized by cancer of the large intestine (colon) and rectum. People with the classic type of familia l adenomatous polyposis may begin to develop multiple noncancerous (benign) growths (polyps) in the colon as early as their teenage years. Unless the colon is removed, these polyps will become malignant (cancerous). The avera ge age at which an individual develops colon cancer in classic familial ade nomatous polyposis is 39 years. Some people have a variant of the disorder, called attenuated familial adenomatous polyposis, in which polyp growth is delayed. The average age of colorectal cancer onset for attenuated familia l adenomatous polyposis is 55 years.
In people with classic familial adenomatous polyposi s, the number of polyps increases with age, and hundreds to thousands of po lyps can develop in the colon. Also of particular significance are noncance rous growths called desmoid tumors. These fibrous tumors usually occur in t he tissue covering the intestines and may be provoked by surgery to remove the colon. Desmoid tumors tend to recur after they are surgically removed. In both classic familial adenomatous polyposis and its attenuated variant, benign and malignant tumors are sometimes found in other places in the body , including the duodenum (a section of the small intestine), stomach, bones , skin, and other tissues. People who have colon polyps as well as growths outside the colon are sometimes described as having Gardner syndrome.
A milder type of fa milial adenomatous polyposis, called autosomal recessive familial adenomato us polyposis, has also been identified. People with the autosomal recessive type of this disorder have fewer polyps than those with the classic type. Fewer than 100 polyps typically develop, rather than hundreds or thousands. The autosomal recessive type of this disorder is caused by mutations in a different gene than the classic and attenuated types of familial adenomatou s polyposis.
How common is familial adenomatous polyposis?
The reported inc idence of familial adenomatous polyposis varies from 1 in 7,000 to 1 in 22, 000 individuals.
What genes are related to familial adenomatous polyposis?<
/h2> Mutat
ions in the APC
gene cause both classic and attenuated familial adenomatous polyposis. Thes
e mutations affect the ability of the cell to maintain normal growth and fu
nction. Cell overgrowth resulting from mutations in the APC gene leads to the colon polyps
seen in familial adenomatous polyposis. Although most people with mutations
in the APC gene
will develop colorectal cancer, the number of polyps and the time frame in
which they become malignant depend on the location of the mutation in the
gene.
Mutation
s in the MUTYH g
ene cause autosomal recessive familial adenomatous polyposis (also called M
YH-associated polyposis). Mutations in this gene prevent cells from correct
ing mistakes that are made when DNA is copied (DNA replication) in preparat
ion for cell division. As these mistakes build up in a person's DNA, the li
kelihood of cell overgrowth increases, leading to colon polyps and the poss
ibility of colon cancer.
How do people inheri
t familial adenomatous polyposis?
Familial adenomatous polyposis can have differ
ent inheritance patterns.
When familial adenomatous polyposis results from mutations in t
he APC gene, it
is inherited in an autosomal dominant pattern, which means one copy of the
altered gene in each cell is sufficient to cause the disorder. In most case
s, an affected person has one parent with the condition.
When familial adenomatous polypo
sis results from mutations in the MUTYH gene, it is inherited in an autosomal recessive pat
tern, which means both copies of the gene in each cell have mutations. Most
often, the parents of an individual with an autosomal recessive condition
each carry one copy of the mutated gene, but do not show signs and symptoms
of the condition.
Mutat ions in the APC gene cause both classic and attenuated familial adenomatous polyposis. Thes e mutations affect the ability of the cell to maintain normal growth and fu nction. Cell overgrowth resulting from mutations in the APC gene leads to the colon polyps seen in familial adenomatous polyposis. Although most people with mutations in the APC gene will develop colorectal cancer, the number of polyps and the time frame in which they become malignant depend on the location of the mutation in the gene.
Mutation s in the MUTYH g ene cause autosomal recessive familial adenomatous polyposis (also called M YH-associated polyposis). Mutations in this gene prevent cells from correct ing mistakes that are made when DNA is copied (DNA replication) in preparat ion for cell division. As these mistakes build up in a person's DNA, the li kelihood of cell overgrowth increases, leading to colon polyps and the poss ibility of colon cancer.
Familial adenomatous polyposis can have differ ent inheritance patterns.
When familial adenomatous polyposis results from mutations in t he APC gene, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most case s, an affected person has one parent with the condition.
When familial adenomatous polypo sis results from mutations in the MUTYH gene, it is inherited in an autosomal recessive pat tern, which means both copies of the gene in each cell have mutations. Most often, the parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but do not show signs and symptoms of the condition.