what is galactosemia?
Galactosemia is a group of rare genetic metabolic disorders characterized by impaired galactose metabolism resulting in a range of variable manifestations encompassing a severe, life-threatening disease (classic galactosemia), a rare mild form (galactokinase deficiency) causing cataract, and a very rare form with variable severity (galactose epimerase deficiency) resembling classic galactosemia in the severe form (see these terms).
What causes Galactosemia?
Galactosemia can be caused by mutations or defects in any of three genes: galactokinase one (GALK1), UDP-galactose-4-epimerase (GALE), or galactose-1-phosphate uridyl transferase (GALT). Most common galactosemis is caused by mutation in the GALT gene. The GALT gene normally provides instructions for making an enzyme that fuctions in liver cells to break down the sugar galactose. Galactose is normally broken down into another sugar called glucose, which is used by the body to generate energy.
Galactosemia is found on the GALT gene, chromosome 9p12
Phenotype of Galactosemia?
Galactosemia is usually found early on in child development. If a galactosemic child is given milk, the unmetabolized milk sugars build up and damage the liver, eyes, kidneys, and brain.
How to diagnose Galactosemia?
Babies are screened for galacosemia at birth as routine newborn screening. Newborns are screened for galactosemia using a blood sample taken as a heel prick test. The drop of blood is then dried and checked for the GALT enzyme. Genetic testing to look for mutations in the GALT gene may be useful in confirming a diagnosis. If infants born with galacosemia are left untreated, die in 75% of cases
A baby being tested for galactosemia
how is galactosemia treated?
Galactosemia is only treated in one way, through dietary restrictions. People with galactosemia must stay away from foods and drinks containing galactose, including milk, cheese, and legumes (dried beans).
is galactosemia heritable?
Galactosemia is inherited in an autosomal recesssive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but typically do not show signs and symptoms of the condition.
Galactosemia being inherited