Transcript No Slide Title

By: Nicholas Chan
D Core
Fabry disease is a genetic disease passed on from parents to children. It is a disorder
caused by lack of enzyme (chemical substances formed by living things, which will
change other chemical substances if it didn’t change it self) needed to metabolize
lipids, or fat. The excess buildup of a particular type of fat in the body’s cells leads to
problems that affect many parts of the body. If the gene that controls the enzyme is
mutated, then the lipids will break down which will then have harmful effects on the
eye level, kidneys, autonomic nervous system and cardiovascular system. This disease
occurs during childhood. The child will begin by having hot sensations in the hand
which will get worse when the child is exercising and in hot weather. Then small raised
reddish-purple marks will appear on the skin. The lipids will go to the heart and be
stored there which will lead to a heart attack or a stroke. The heart maybe enlarged and
the kidneys may become more progressively involved. Other symptoms may occur such
as reduced sweating, fever and gastrointestinal difficulties after a meal. This disease is
X recessive which means it affects males more than it does females since the gene
affected by Fabry disease is the X chromosome. Males have only one X while females
have a second X and therefore have some enzyme activity even though one of the X
chromosomes is affected by Fabry disease.
X recessive is a weak X chromosome, which is inherited by a male or a female.
The chances of a male having this disease if either of his parents have the
disease or carries it is higher than a female. The female contains 2 “X”
chromosomes while the male has only one X chromosome, this shows that the
women has less likely to show the affected symptoms since it has a dominant X.
But if the male gets the mutated recessive “Xr” then he will be affected by it,
this is because it has only one X chromosome. Therefore there is a higher
percentage that he will have the symptoms and be affected by it. It is also likely
to be shown because the male only has one chance to be normal, this is
necessarily a hemizygous. Because of this inheritance pattern, it is impossible
for the male to be a carrier. But even though the female has one X recessive
while the other X chromosome is unaffected, it doesn't mean that the symptom
cannot be shown from the homozygous female. Also, it is rare for a women to
have the symptoms/disease expressed in a phenotype( symptoms shown
physically) (because of this pattern). And the female has 2 chances since it has
two X chromosomes, so a female has a higher chance of not being affected by
the Disease than the male.
Fabry Disease Punnett Square’s
Genotype: XX/XY: XXr: XrXr/XrY
Female
X
Male
X
Y
XX
XY
X = Dominant
Phenotype: 3:1 Sick:not sick/carriers
r
X
XXr
XrY
In this situation,2 child’s are not
affected by the disease.
Xr = Recessive
(Disease)
1 “XXr” is a carrier (female) and 1
has the disease (male)
Parents: Male: Not affected,
Female: Carrier.
Female
X
Male Xr
Y
XXr
XY
X
XXr
XY
If the mother is not a
carrier nor affected by
the disease while the
father is affected by the
disease, the 2 males will
be affected by the
disease, while the 2
females are fine.
Genotype:XX/XY: XXr: XrY/XrXr
Phenotype: 4:0 Carrier/normal: Sick
Female
Male
X
X
XX
X
XX
Y
XY
XY
If both parents are fine, not having the
disease, or carriers of the disease, all
of the children will be fine.
Genotype:XX/XY: XXr: XrY/XrXr
Phenotype: 4:0 Not sick: Sick
Female
X
Xr
Male
Xr
XrXr
XXr
Y
XY
Genotype: XX/XY: XXr: XrY/XrXr
Phenotype:2:2 Sick:not sick, carriers
If the Mother is a carrier, and the father is having
the disease, 1 female is a carrier, 1 female is
affected by the disease, 1 male isn't affected by
the disease nor a carrier, and 1 boy has affected by
the disease.
Xr Y
Female
Male Xr
Female
Xr
Male
Xr
Xr
XrXr
XrXr
If both parents have
a disease, all of the
children will be
having the disease.
(in this case)
Xr
X
XXr
XXr
Y
XrY
XrY
In this case when the mother is
having a homozygous recessive
r
r
gene and marries a homozygous
dominant male, the 2 males will
Genotype:XX/XY: XXr: XrY/XrXr
Genotype:XX/XY: XXr: XrY/XrXr have the disease while the 2 females
Phenotype: 4:0 Sick:not sick
will be carriers of the disease.
Phenotype:2:2 Carriers:Sick
Y
XY
X Y
•http://en.wikipedia.org/wiki/X-linked_recessive
•http://en.wikipedia.org/wiki/Fabry_disease
•http://www.medicineonline.com/dictionary/abry-disease.html
•http://www.ninds.nih.gov/disorders/fabrys/fabrys.htm#Is_there_an
y_treatment
•http://ghr.nlm.nih.gov/condition=fabrydisease