Nowadays, we know that Diamine Oxidase deficiency (DAO deficiency) may be primary or secondary, which is the same as saying genetic or acquired. Therefore, DAO deficiency can be hereditary and in fact it is its main cause.
It is important to remember that what we inherit is the enzymatic deficiency but not the symptomatology. In the same family we can find people with DAO deficiency, but with different associated symptoms. For example: a mother with migraine and non-allergic rhinitis, a son with hives and digestive disorders and an uncle with chronic fatigue and digestive disorders.
AOC1 is the gene that codes for the synthesis of the DAO enzyme. When there is a genetic alteration in AOC1, the DAO enzyme produced has an abnormal structure and, consequently, less effective in its main function: the degradation of histamine from the diet.
What test should I request for?
To know if the DAO deficiency has a genetic origin, a molecular genetic study of Diamino Oxidase deficit must be performed. In this study 4 variants of the AOC1 gene are studied, which, in scientific literature, have been associated with reduced levels of DAO activity with a lower capacity for histamine degradation:
- AOC1 c.47C>T (p.Thr16Met)
- AOC1 c.995C>T (p.Ser332Phe)
- AOC1 c.1990C>G (p.His664Asp)
- AOC1 c.691G>T
For all variants, a CC result indicates a normal production of the DAO enzyme, while a CT, CG, TT or GG result indicates an abnormal production of the enzyme and therefore a higher risk of DAO deficiency. In addition, the p.T16Met variant has been associated with an increased risk of hypersensitivity to NSAIDs (Non-Steroidal Anti-Inflammatory Drugs, such as Acetylsalicylic Acid or Ibuprofen. In turn, they inhibit the function of DAO activity).
Below, we show the main differences between the genetic test and the enzymatic activity test:
Genetic test (+info)
|It reports the existence or not of a genetic alteration for the formation of the DAO enzyme
|It measures the enzymatic activity of DAO at the time of analysis
|It is evaluated in blood or oral mucosa (non-invasive)
|It can only be evaluated in blood (invasive)
|It is evaluated in DNA
|It is evaluated in blood plasma
|It is measured in variants of G, T and / or C alleles
|It is measured in HDU/ml o U/ml units
|Normality: Negative (CC for all variants)
|Normality: >80 HDU/ml or >12,54 U/ml
|The result does not vary. It is done once in a lifetime
|The result varies from one take to another
|The result is not influenced by external factors
|The result may be influenced by several factors: taking drugs, drinking alcohol, intestinal inflammation, surgical interventions, menstrual period…
|It is not covered by Social Security and it costs around 120€ (a few years ago it cost more than 300€)
|Some autonomous communities or private health insurances cover it and costs around 70€
|It must be prescribed by a healthcare professional
|In some laboratories the patient can request the test without prescription
Until the beginning of 2019 we only had the option to recommend the DAO activity test, because the genetic test was very expensive. But now, thanks to a more modern technology, we consider very interesting to ask the genetic test for all our patients, specially if there exist family history. With a sample of oral mucosa we can know if there is any genetic polymorphism and therefore, intuit how the patient’s DAO activity will evolve and which treatment will be the most appropriate.
So, if the genetic test is positive, will I never be cured?
To suffer DAO deficiency with a genetic origin means that, by genetics, an enzyme with abnormal structure will always be produced and not at all effective. Even so, the levels of enzymatic activity not only depend on genetics, but also are influenced by other secondary factors (intestinal inflammatory diseases, taking of certain DAO enzyme blocking drugs, consumption of alcoholic beverages, surgical interventions, menstrual period, etc.). Therefore, the levels of enzyme activity can be improved to a greater or lesser extent with a healthy lifestyle and taking into account these factors together with a specialized professional. But if the genetic factor exists, it will be essential to follow a low histamine diet more or less strict throughout life to control the symptoms.
In AD Dietistas we managed to see a great improvement in the majority of the patients we visit, either because they have a genetic and/or acquired DAO deficiency. If you want us to advise you in a personalized way, either in our Barcelona centre or by videoconference from anywhere in the world, contact us and we will help you.