|
|
|
Mosaicism
|
|
|
In this condition a change occurs in the structure or shape of the chromosome or in the chromosome arrangement usually after
the fetus is formed.
Here the fetus starts developing in the uterus with a normal chromosome arrangement,
but when it reaches the stage of multiple cells, one cell might develop a chromosome
anomaly. From then on, all the cells that are derived from this one cell will also
contain the same abnormal chromosome arrangement. This means that in certain body
organs the person has a combination of cells, some with a normal genetic structure
and others with an abnormal genetic structure. This situation is known as mosaicism.
The clinical significance of mosaicism depends on the number of abnormal cells and
their function, i.e. what they are responsible for.
In most cases a chromosome disorder resulting from mosaicism is milder than one
that occurs when all the cells have the same abnormal chromosome arrangement. Because
mosaicism is present in only some of the body organs, tissues and cells, there is
a possibility that it will not be diagnosed in chromosome tests performed on blood
or amniotic fluid.
|
|
|