"Cells
normally carry two matched sets of twenty-three chromosomes for a total
of forty-six chromosomes. One set of twenty-three chromosomes comes
from each parent. Down's syndrome occurs when one chromosome pair is
damaged. That pair is designed as chromosome # twenty-one." (Newton,
259)
There
are several symptoms that come from Down syndrome but there are also
some characteristics that go along with it: the syndrome is suspected
when many characteristics occur in an individual.
"Characteristics
include flat face, small head, flat bridge at end of nose, low-set nose,
small mouth, upward slanting eyes, extra folds of skin at inside corner
of each eye, rounded cheeks, small ears, small hands, deep crease across
center of palm, malformed fifth finger, wide space between the big and
second toe, unusual creases of sole of feet, overly-flexible joints,
and people with Downs syndrome tend to be shorter than normal."
(Newton, 261)
There
are several disorders that accompany Down syndrome. "One of them
is gastrointestinal (digestive) tract disorders, and they affect about
five to seven percent of all children with Downs. The most common problem
among babies is an obstruction (narrowing or closing) of the intestine,
where digestion takes place. This obstruction can interrupt the digestion
of food, and a baby may vomit after eating. As a result, the baby has
problems gaining weight appropriately." (Newton, 261)
"Other
medical conditions that may accompany DS include an increased risk of
infections, especially ear infections and pneumonia; certain kidney
disorders, heart defects, thyroid disease, hearing loss, vision problems,
and a greatly increased risk for leukemia." (Newton, 261)
"As
people with Downs Syndrome age, they face increased risks for several
diseases. One of these diseases is the Alzheimer's disease. The risk
of developing Alzheimer's in the general population is six in one hundred.
However people with DS have a risk of twenty-five in one hundred. Aging
also increases the risk for cataracts, thyroid problems, and diabetes
and seizure disorders." (Newton, 261)
There
are three different types of Down Syndrome; Straight Trisomy 21, Mosaic
and Translocation. People with Mosaic Down Syndrome are generally higher
functioning and have fewer characteristics of Down Syndrome than with
Straight Trisomy 21 and Translocation.
Although the exact cause of Down Syndrome is still unknown scientist
do understand what having the extra chromosome does to the genetic make-up
of the individual. "Chromosome twenty-one can be damaged, for example,
if one parent has two chromosomes at location twenty-one, rather than
one. A child will get two number twenty-one chromosomes from one parent
and one number twenty-one chromosome from the other parent, for a total
of three number twenty-one chromosomes. This form of Down's syndrome
is called Trisomy twenty-one, meaning that the number twenty-one chromosome
has three units rather than forty-six chromosomes. This pattern of changes
occurs in more than ninety percent of all Down's patients."(Newton,
260)
Babies with Down syndrome can often be diagnosed at birth because of
some common health issues. For example, they tend to be unusually quiet
and less responsive, resulting in low Apgar scores at birth.
This is not always evident in infants that have Mosaic Down Syndrome.
They generally have less physical characteristics and are more active
at birth. Every time a baby is born that has the characteristics of
a person with
Downs a chromosome study of the child is done. Normally a person has
forty-six chromosomes. Persons with Down syndrome, however, have forty-seven
chromosomes.
"When
Mosaicism is discovered, it is often described as a percentage of cells
having additional chromosome twenty-one material. For example, a blood
test may be done on a baby who has the features of Down Syndrome. Typically,
the chromosomes of twenty different cells are analyzed. If it is found
that there are five cells with the expected number of chromosomes and
there are fifteen cells with forty-seven chromosomes, including an extra
chromosome twenty-one, the baby would be described as having Mosaic
Down Syndrome. In the case, twenty-five percent of the cells have extra
chromosome twenty-one material. In this example, then, the baby may
only be described as having Mosaic Down syndrome with a Mosaicism level
of seventy-five percent." (Jackson-Cook, 3)
"One
way that Mosaicism arises is through nondisjuctional event during mitosis.
This occurs after conception. During conception, a sperm and egg cell,
each with twenty-three chromosomes come together, completing fertilization.
Later, after several cells have been made, one cell has difficulty splitting
its chromosomes evenly. The result can be one cell with forty-seven
chromosomes and three chromosomes twenty-one. This cell continues to
make new identical cells, through mitosis, and each new cell will also
have an extra chromosome twenty-one." (Jackson-Cook, 4)
"The
second sequences of events that can lead to Mosaicism involve nondisjuctional
occurring twice. The first nondisjuctional event occurs when a sperm
or egg cell is made. The sperm or egg cell has twenty-four chromosomes,
with an extra chromosome twenty-one. If the story ended here the baby
would have Trisomy twenty-one, without Mosaicism. However, in cases
with Mosaicism another nondisjuctional event happens after conception.
As the cells of the embryo begin to make copies of them, the extra chromosome
twenty-one is lost from one of the cells, and a new cell is made with
forty-six chromosomes instead of forty-seven. As each of these cells
continues to double, it leads to a baby with two different types of
cells, or Mosaicism." (Jackson-Cook, 4)
When
asked about there children's health there was a few conditions mentioned.
"Most children and adults with Mosaic Down Syndrome had surgeries
for the health conditions that they were either born with or acquired.
About fifty-six percent had one or more surgeries. The most common procedure
was the placement of tubes in the ears to drain the fluid. Tonsillectomies
and procedures to open blocked tear ducts were also common. A few individuals
had surgery to correct strabismus, a condition where both eyes do not
move together and appear crossed." (Jackson-Cook, 10)
"Another
issue in Down's Syndrome is excessive weight gain, which is reported
to occur in about twenty-five percent of individuals with full Down
syndrome. This usually occurs around the time of puberty. Given the
relatively young ages of members of the group, additional individuals
may experience weight gain later in life. Several families noted that
they tried to establish good eating and exercise patterns to prevent
gain. In describing strategies to control weight, common themes were
education and supervision. Specifically, parents described teaching
their children to reduce fats and eat healthy foods, supervising food
access, limiting snacks, and encouraging exercise." (Jackson-Cook,
10)
There
are many sides to every story. Even one to such a broad statement as
people with Mosaic Down syndrome has fewer side effects to the syndrome
as to the people with mosaics Down syndrome.
"Chromosome
number twenty-one can be damaged during cell reproduction. Cells grow
and reproduce over time. As they do so, they make copies of the original
chromosomes from the parents. Sometimes, the chromosomes from the parents
are normal but a problem occurs when the new cells are reproducing.
Two normal chromosomes at location twenty-one become three chromosomes
in some cells."(Newton, 260)
"This
condition is known as a mosaic disorder. People with this disorder have
some cells containing forty-six chromosomes, and some containing forty-seven
chromosomes. They may have less severe symptoms than a person may whose
cells all contain forty-seven chromosomes. A mosaic condition rarely
occurs. Less than two percent of all Down's cases are caused by mosaic
disorder." (Newton, 260)
When
asked about there children's health there was a few issues mentioned.
"Most of these were related to the respiratory tract or ears. The
most commonly mentioned health problems were recurrent ear infections
and common colds or upper respiratory infections. Respiratory infections
affected the nasal passages, throat and lungs. Also mentioned were asthma,
allergies, bronchitis, pneumonia, sinus infections and blocked tear
ducts." (Colleen Jackson-Cook, www.mosaicdownsyndrome.com/study.htm)
In
the past four years I have joined and participated in an international
Internet support group for Mosaic Down Syndrome. I have two hundred
acquaintances and at least fifty of those have become some of my close
friends. I e-mailed all fifty, only getting forty-five replies to my
request of asking to get information from there parents about them.
I did this so that I could make a chart of their symptoms.
After
interviewing all forty-five parents and researching extensively on Down
syndrome I was able to conduct several charts. These charts represent
whether or not the individuals had differences or similarities, and
the extent of them, to Mosaic Down Syndrome and Down syndrome.
Mosaic Down Syndrome Characteristics Down syndrome Characteristics:
Low muscle tone at birth Flat face
Face appears flat Small head
Epicanthic folds Flat bridge of the nose
Eyes slant upwards Smaller than normal nose
Protruding tongue Small mouth
Hearing loss Upward slanting eyes
Loose joints Extra folds of skin at corner of eye
Crease along palm of hand Rounded cheeks
Excess skin around neck Small, misshapen ears
Straight, fine hair Small, wide hand
Unusually dry skin crease across center of palm
Gastrointestinal problems Malformed fifth finger
space between big and second toes
Unusual creases on soles of feet
Overly-flexible joints
Shorter than normal height
I found nine Differences:
Low muscle tone at birth
Hearing loss
Straight hair
Heart problem
Excess skin around neck
Dry skin
I
found six Similarities:
Flat face
Epicanthic folds
Eyes slant upward
Protruding tongue
Loose joints
Crease along palms
From my intensive research and interviews I found 6 similarities. Yet
I also found 9 different characteristics from Mosaic Down Syndrome and
Down syndrome. So I conclude that there where more features in DS than
in MDS.
