Acatalasemia

Acatalasemia

AcatalasemiaDescription, Causes and Risk Factors of Acatalasemia:

Absence or deficiency of catalase from blood and tissues, often manifested by recurrent infection or ulceration of the gums and related oral structures and caused by mutations in the catalase gene (CAT) on 11p. Homozygotes may have complete absence (Japanese variety) or very low levels (Swiss variety) of catalase; heterozygotes have reduced catalase levels (hypocatalasia), which overlap with the normal range.

A Japanese otolaryngologist first reported this new disease. He had examined a patient with an oral ulcer. He had spread hydrogen peroxide on the diseased part, but oxygen was not generated due to the lack of catalase.

Acatalasemia is a rare autosomal recessive disorder resulting from the absence of catalase enzyme activity. The enzyme catalase is involved in the protection against hydrogen peroxide. Enzyme catalase seems to be the main regulator of hydrogen peroxide metabolism. Hydrogen peroxide at high concentrations is a toxic agent, while at low concentrations it appears to regulate some physiological processes such as signaling in cell growth, cell death, carbohydrate metabolism, and platelet activation. A significant reduction of activity of catalase has been observed in dogs with localized and generalized demodicosis and antioxidant supplementation may be beneficial in management of canine demodicosis.

Related article: Vitamin B12 deficiency

All aerobic organisms use molecular oxygen for respiration or oxidation of nutrients to obtain energy efficiently. During the transformation of molecular oxygen to water, reactive oxygen species such as the superoxide radical, hydrogen peroxide and the hydroxyl radicals are generated. While only a weak oxidant, hydrogen peroxide has high potential to produce damage due to its ability to penetrate and spread freely across cell membranes. Hydrogen peroxide in the form of carbamide peroxide (CH6N2O3) is widely used in professionally and self-administered products for tooth whitening. It is a highly reactive substance that can damage oral soft and hard tissues when present in high concentrations and with exposures of prolonged duration with possible cancer-causing side effects. All of the above species are capable of damaging DNA, protein and lipid membranes, and are known to be causative factors in degenerative diseases such as cancer. For defence against reactive oxygen species, cells contain antioxidative enzymes such as superoxide dismutase, catalase and several peroxidases, as well as antioxidants such as ascorbate, tocopherol and glutathione. For example, extracellular superoxide dismutase is an antioxidant that protects the heart from damage to heart muscle, disruption of heart rhythms, and lung disease from inflammation and fibrosis. Red blood cells contain large amounts of catalase and are believed to act as a sink for hydrogen peroxide and superoxide removal.

The researchers believe that abnormality is on chromosome 11 at gene map locus 11p13. Homozygotes for the gene have a marked deficiency of catalase and heterozygotes have an intermediate level. It has been suggested that the affinity of catalase for hydrogen peroxide (H2O2) is poor and that a more important enzyme is glutathione peroxidase.

According to recent scientific studies, low levels of catalase may play a role in the graying process of human hair. Hydrogen peroxide is naturally produced by the body and catalase breaks it down. If catalase levels decline, hydrogen peroxide cannot be broken down as well. This allows the hydrogen peroxide to bleach the hair from the inside out. This finding may someday be incorporated into treatments for graying hair.

Symptoms of Acatalasemia:

Most cases are asymptomatic and acatalasemiamay be seen as disease in search of some symptoms. Its clinical features include oral gangrene, altered metabolism of lipids, carbohydrate and homocysteine and an increased risk of diabetes mellitus.

Oral lesions, especially progressive gangrene of the gums, appears to be the most common presentation where there is overt disease and severe enzyme deficiency. In the original case, presentation was progressive oral gangrene.

  • In most cases there is some catalase activity and so the disease appears to be benign but there may be risks of exposure to oxidants and a series of Hungarian patients found an excessive incidence of diabetes mellitus amongst those with catalase deficiency.
  • The impaired ability to deal with oxidative stress may predispose to atherosclerosis.However, the levels of atherosclerosis and subsequent related diseases are not as high as one might expect in this group. This suggests that there may other natural antioxidants in vivo. There is extensive research on the role of antioxidants such as vitamins E and C in terms of protection; however, the evidence is inconclusive.
  • There is evidence that catalase deficiency predisposes to skin damage by ultraviolet light.
  • There is a suggestion that catalase deficiency may be associated with aniridia (absence or defect of the iris), Wilms' tumour and mild-to-moderate mental deficiency.

Diagnosis:

Catalase activity is usually measured in the erythrocytes.

Treatment:

The literature does not offer guidance on progressive oral gangrene, and patients should be referred to specialists urgently. However, prompt treatment of oral infections is advised. This should be followed by attention to oral hygiene.

Vitamin E supplementation in acatalasaemic mice protects against tumour formation. However, this has not been evaluated in humans.

Some recent work has reported that patients at risk of tumor lysis syndrome can develop very high hydrogen peroxide levels when given uric acid oxidase treatment. The cause of this is unclear and needs to be evaluated further. Patients with low (inherited and acquired) catalase activities who are treated with infusion of uric acid oxidase because they are at risk of tumour lysis syndrome may experience very high concentrations of hydrogen peroxide. They may suffer from methemoglobinaemia and haemolytic anaemia which may be attributed either to deficiency of glucose-6-phosphate dehydrogenase or to other unknown circumstances. Data have not been reported from catalase deficient patients who were treated with uric acid oxidase. It may be hypothesized that their decreased blood catalase could lead to the increased concentration of hydrogen peroxide which may cause haemolysis and formation of methemoglobin. Blood catalase activity should be measured for patients at risk of tumour lysis syndrome prior to uric acid oxidase treatment.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.

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