-
What is G6PD deficiency?
Glucose-6-phosphate
dehydrogenase
deficiency,
or
G6PD
deficiency
for
short,
is
the
most common “inborn metabolic disorder”
in the world. This means that from the
time a
baby
is
born,
thre
is
already
something
wrong
with
how
his
body
makes
and
breaks
important
substances.
According
to
statistics,
about
400
million
people
have
G6PD
deficiency, and it is most common in
Africa, Southeast Asia and the Middle
with
G6PD
deficiency
have
very
little
or
no
enzyme
called
Glucose-6-Phosphate
Dehydrogenase
(G6PD).
An
enzyme
is
a
kind
of
protein
that
speeds
up
chemical
reactions in the
body. The enzyme G6PD is especially important to
red blood cells. If this
enzyme is
lacking or missing, red blood cells are easily
destroyed.
Another name for G6PD
deficiency is favism because some people who have
it, usually
those living in the
Meditteranean region, react very badly to fava
beans.
What causes G6PD
deficiency?
In
order
to
understand
what
causes
G6PD
deficiency,
one
must
first
learn
a
bit
about
genes and chromosomes.
Genes
are like the body’s blueprints. They contain
instructions on how specific parts of the
body are made. For example, if the
isntructions in your hair genes say your hair is
black,
your
hair
will
be
black.
Genes
are
packaged
into
threadlike
structures
called
chromosomes. A
chromosome is very much like a beaded bracelet.
The beads are the
different genes that
give instructions for different part of the body;
the entire bracelet is the
chromosome.
Genes usually come and act in pairs. One member of
a specific pair comes
from the father,
and the other member comes from the mother. The
members of a pair are
located on paired
chromosomes.
All normal human beings
have 23 pairs of chromosomes. Each of the first 22
pairs contain
the
same
number
and
kind
of
genes.
The
last
and
23rd
pair
is
the
sex
chromosomes.
They are different from the first 22
pairs in that they do not have the same number and
kind of genes. The sex chromosomes
contain the genes that determine whether a baby
will be a girl or a boy.
There are 2 kinds of sex chromosomes, X
and Y
. All baby girls have two X
chromosomes.
All baby boys have one X
and one Y
. The gene that gives
instructions on how G6PD is
made is
found in the X chromosome only, thus G6PD
deficiency is described as X-linked.
If
a baby girl gets one defective G6PD gene from
either of her parents, she will not have
G6PD deficiency because she has another
G6PD gene that can do the work (remember:
a baby girl has two X chromosomes, thus
two G6PD genes). But if she gets two defective
G6PD genes from both her parents, she
will have G6PD deficiency. On the other hand, a
baby boy whose G6PD gene is defective
will surely get G6PD deficiency because the Y
chromosome has no G6PD gene.
A defective G6PD gene will give wrong
instructions on how to make the enzyme G6PD.
As a result, too little or none of it
is made.
What are the harmful effects
of G6PD deficiency?
G6PD has
a very small but strategic role in protecting the
body from substances that can
cause
damage to cells or oxidative substances. Because
of this important role, G6PD is
normally found in all parts of the
body. To be sure, most parts of the body also keep
a
“spare” enzyme, one that can do the
w
ork of G6PD in case it is lacking or
missing entirely.