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Galactosemia

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Galactosemia is a genetically inherited metabolic disorder.  This disorder leaves the disabled with a partial or complete lack of the enzyme Galactose - 1 - Phosphate Uridyl Transferase (GALT).  This enzyme is found in the bloodstream and it is used for breaking down the sugar galactose.  This disorder comes in two different variations.  Though there is more than one type, it is still rare, having only 1 in 80,000 births being affected by the disorder.

Classic Galactosemia is the first and more common form of the disorder.  This is the form when the affected has a complete loss of the enzyme.  Both parents must contribute a galactosemic gene for a child to receive this very deadly form of the disorder.  Because the body has none of the enzyme needed to turn galactose into glucose an accumulation occurs that is like a poison and is highly fatal.  Classic Galactosemia is treatable through a strict diet of absolutely no lactose or galactose.  Some common foods containing these are dairy products, legumes, breast milk, and many other foods.  A test for galactosemia is done at the time of birth with other tests.  If left untreated 75% of infants will die.  Some effects of having classic galactosemia include: an enlarged liver, kidney failure, cataract, and brain damage.

Duarte Galactosemia is the second form.  This form is when there is only a partial loss of the enzyme.  The activity is usually 25%-50% that of a normal child.  A child can get this form of galactosemia by inheriting a classic galactosemia gene from one parent and a duarte gene from the other.  Much like classic galactosemia, duarte is found through a test done soon after birth.  A strict diet is not needed for this form of the disorder.  Instead a diet, it is recommended that lactose be slowly introduced until normal consumption is accepted by the body.  Because the affected can still process the foods, just not as well as a fully functional body.

A person with no galactosemia  receives two normal genes for production of the GALT enzyme in the bloodstream.  This persons genotype is N/N and they have normal fully functioning enzyme activity.  A carrier of classic galactosemia inheriets one affected gene and one non, this persons genotype is G/N.  This person has less than normal enzyme activity, but nothing that requires a diet or medical treatment.  A classic galactosemic has two classic galactosemia genes.  One from each parent.  Their genotype is G/G. someone affected by duarte galactosemia can have one of a few genotypes.  D/N, D/D, and D/G are all options, whereas N means nothing, G means classic, and D means duarte.  D/N is just a duarte carrier but not affected, this person has about 75% enzyme activity.  D/D is affected by duarte galactosemia and has about 50% enzyme activity. D/G is also affected by duarte galactosemia, but this one only has about 25%-50% enzyme activity.

Galactosemia was first discovered in 1908.  A publication titled "Sugar Excretion in Infancy" followed a breast-fed infant.  This infant had no growth in its liver or spleen and had a failure to thrive.  The infant's urine was tested and no galactose was found when diary products were removed from its diet.  This led to a study of the disorder that this infant had.  The infant did not die of galactosemia and was not involved in further study because it died of other cause soon after most discoveries were made.  While performing an autopsy many things were found inside the infant that means nothing to me, but I know they are abnormal.  These abnormalities were connected to the galactosemia.  After much study and research the first detailed description of the disease was published in 1935.  In 1956 it was discovered which gene was linked to galactosemia.  Soon after in 1963 a test was developed for newborns to check for galactosemia.

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CALYN Reviewed this free essay on Oct:09:2008

GALACTOSEMIA IS HARD

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