Uridine Diphosphate Galactose-4-epimerase (GALE) deficiency
What else is it called?
- UDP-Galactose-4-epimerase deficiency
- GALE deficiency
- Epimerase deficiency galactosemia
- Galactosemia type 3
- Uridine diphosphate galactose-4-epimerase deficiency
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What causes it?
This disorder is caused by a problem in the GALE gene. This gene produces the instructions for Galactose-4-epimerase (GALE) which is part of a 3-enzyme pathway that breaks down Galactose. This process is needed to produce energy within the body.
If you have a problem in the GALE gene, you will not produce enough of the GALE enzyme. Therefore, UDP-galactose will not be converted into UDP-glucose. This causes a build-up of Galactose within the body.
There are three forms of GALE deficiency base on how it affects the body:
- Generalised: affects all tissues within the body
- Peripheral: affects only red and white blood cells.
- Intermediate: affects red and white blood cells and over 50% of tissue.
How common is it?
There is no available figure for the prevalence of those with GALE deficiency, but it is known that generalised GALE deficiency is very rare. It is also known that those of European descent have a higher prevalence than those of Japanese and African descent.
What are the signs and symptoms?
The signs and symptoms depend on which form of the deficiency that you have.
Symptoms for the generalised disorder begin from birth; when ingesting breast milk or lactose containing formula the child will develop a range of symptoms such as;
- Hypotonia (decreased muscle tone)
- Weight loss
- Liver disorders
- Aminoaciduria (amino acids within the urine)
In the most severe of cases, these symptoms can be life threatening.
Peripheral/Intermediate forms of the disorder are typically asymptomatic, with the patient being unaffected by their diet.
Following dietary restrictions such as the removal of galactose/lactose from the diet is extremely important in the cases of those diagnosed with the generalised form, it can help prevent reoccurrence of many symptoms. Removal of galactose/lactose from the diets of those with intermediate GALE deficiency can help in the long term but this will be discussed with a specialist dietician individually.
Due to the limited statistics available, a life expectancy for patients with GALE deficiency cannot be accurately stated.
How is it diagnosed?
GALE deficiency can be picked up on by measuring the total galactose concentration within the body and by determining the activity of the GALT enzyme. Follow up tests will be performed if the results suggest GALE deficiency.
Molecular testing via sequencing of the GALE gene can also be performed to give a confirmed diagnosis.
A test performed on a leukocyte (white blood cell) cell will confirm which form on GALE deficiency the patient has.
GALE deficiency is currently not tested for within the newborn screening test in the UK, but in the US, certain states do test for it within their newborn screening procedures.
Can it be treated?
As previously mentioned, treatment for the generalised form of GALE deficiency is mainly through the removal of galactose/lactose from the diet. This restriction of the diet may continue into the end stages of childhood. A specialist dietician will talk to you about treatment plans.
For intermediate GALE deficiency, removal of galactose/lactose from the diet is suggested as treatment, to prevent any potential long-term effects. Again, a specialist dietician will speak to you about treatment options.
For peripheral GALE deficiency, no treatment is necessary.
Do my family need to be tested?
GALE deficiency is an autosomal recessive disease, meaning that a faulty copy of the gene must be inherited from both parents, giving a 25% chance of the child being born with the disorder. There is a 50% chance that the child will be born a carrier, which means that the child will only inherit one copy of the gene and cannot develop GALE deficiency.
As it is an autosomal recessive disorder, members of your family may be carriers, or they may have the deficiency and do not know. Genetic testing can be done for the disorder and can catch the disorder early on. Identifying carriers within your family can also assist in any family planning.
Image 1: Diagram showing inheritance patterns between two carrier parents for an autosomal recessive disorder, like GALE deficiency