Causes of Acatalasemia

Acatalasemia is caused by mutations (changes) in the CAT gene. This gene is responsible for giving instructions for making the enzyme catalase which breaks down hydrogen peroxide molecules into oxygen and water.

Hydrogen peroxide is formed through chemical reactions within the cells. At low levels, it is used in chemical signalling pathways however, at high levels it is toxic to the cells. If hydrogen peroxide is not broken down by the enzyme catalase, it will be converted into compounds called reactive oxygen species that can damage DNA, proteins and cell membranes.  

Mutations (changes) in the CAT gene greatly decreases the activity of the enzyme catalase. A lack of this enzyme can cause hydrogen peroxide to build up to toxic levels in certain cells. An example is a build-up of hydrogen peroxide produced by bacteria in the mouth can build up and damage soft tissues causing mouth ulcers and gangrene (a serious condition where a loss of blood supply causes body tissue to die). The build up of hydrogen peroxide also causes damage to beta cells of the pancreas which release insulin that controls blood sugar levels. This is why individuals with Acatalasemia are at risk to type 2 diabetes.  

It is common for people to have reduced catalase activity with no identified mutation in the CAT gene. The cause of the condition in these cases is unknown.   

How common is it?

More than 100 cases of this condition have been reported. It is estimated that the condition occurs in about 1 in 12,500 people in Japan, 1 in 20,000 people in Hungary and 1 in 25,000 people in Switzerland. The prevalence of this condition in other populations in unknown.