Cowden Syndrome
A Guide for patients and their families
How is Cowden Syndrome Inherited?
Sarah Burton, UI Health Care
Joy Larsen Haidle, MS, CGC, UI Health Care
Heather Hampel, MS, CGC, Ohio State University
Charis Eng, MD, PhD, Ohio State University
Peer Review Status: Internally reviewed by the
authors
First Published:
Last Revised: April 2002
Cowden syndrome can be inherited or passed from
an affected parent to a child. While this is a common way to receive
a gene change, it is not the only way. New gene changes (de novo) can
occur by chance in the sperm or egg that formed an individual. A new
gene change is not the result of something that did or did not happen
in pregnancy nor can it be prevented. This type of change can result
in a condition occurring in someone who does not have family history
of that condition.
CS is described as having an autosomal dominant
pattern of inheritance. Autosomal describes genes that are passed
equally from parent to child with no preference between males and
females. Dominant describes a gene change that causes the features of
a condition to be present when one copy of the gene has been
changed. This means that each child with an affected
parent has a 50 percent chance of inheriting the gene change and
developing CS. Likewise the child has a 50 percent chance of not
inheriting the gene change and not developing CS (see diagram 3).
An evaluation of your family history can determine if a pattern exists. A family tree or a pedigree is a diagram of the members of
your extended family.
Diagram 3. This diagram shows how one gene
from each parent is passed to a child. In the case above the father
has one working gene, indicated by the lower case letter n, and one
gene with a change, indicated by the capital letter N. The mother has
two copies of normal genes. There are four possibilities of gene
combinations for the child. Each child has a 50% chance of inheriting
the changed gene (N), regardless of the sex of the
child.
Below is a pedigree that demonstrates the
pattern of autosomal dominant inheritance within a family.
This pedigree tells us several things about this family.
1) Sue and Tom have three kids, two of whom are
affected. Since Sue was affected, each child had a 50 percent chance
for developing Cowden syndrome, but only Joe and Jim actually
inherited the gene change.
2) Sara did not inherit the gene change and has
not developed CS. She cannot pass this gene on to her children, nor
will they develop CS.
3) Joe has one daughter who had a 50 percent
chance of inheriting the gene change and developing CS. Jen did not
inherit the change, will not develop CS, and cannot pass the gene
change to her children.
4) Kay and Jim have two children; one inherited
the gene change. Tim inherited the gene change and he now has a 50
percent chance of passing this gene on to his children. Lori did not
inherit the change and cannot pass the gene on to her children.
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