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DIO2 (Deiodinase 2 Gene) Genetic Test

Click here to download the DI02 (Deiodinase 2 ) Gene
Genetic Testing Order Information

Thyroid UK is very pleased to inform you that we are now working with Regenerus Laboratories Ltd in respect of the DIO2 Genetic test.

Lab workersThe DIO2 gene was researched in 2009 and the results were published in the paper entitled,

"Common Variation in the DIO2 Gene Predicts Baseline Psychological Well-Being and Response to Combination Thyroxine Plus Triiodothyronine Therapy in Hypothyroid Patients"
by V Panicker, P Saravanan, B Vaidya, J Evans, A Hattersley, T Frayling & C Dayan


Firstly, you need to know that everyone inherits two copies of each gene, one from their mother and one from their father.

To explain this paper briefly, the DIO2 gene activates tri-iodothyronine (T3) and the researchers found that a tiny fault in this gene could mean that although the body gets enough T3, the brain doesn’t. 

The researchers found that patients on levothyroxine (T4) alone felt worse if the faulty DIO2 gene was inherited through one parent and worse still if they inherited the faulty gene from both parents.

The patients on this study were given T4 only for a set period and then combination treatment of both T4 and T3.  The patients who had normal genes did not feel any different on combination treatment.  However, those who had one faulty gene felt better on the combination treatment and those with both faulty genes felt better still.

This means that there is a possibility that patients who are on levothyroxine alone and still have symptoms may improve with the addition of T3.

Because this faulty gene causes a deficiency of T3 within the cells, the usual thyroid hormone function tests will not show up a problem.  This means that your TSH, FT4 and FT3 blood tests will look normal.

The study concluded,

“Our results require replication but suggest that commonly inherited variation in the DIO2 gene is associated both with impaired baseline psychological well-being on T4 and enhanced response to combination T4/T3 therapy, but did not affect serum thyroid hormone levels.”

In order to find out if you have the faulty gene, you need to have the DIO2 genetic test which Thyroid UK has now sourced in the UK.

Various guidelines recommend that you can only have this test done if you receive pre and post “Counselling” and Regenerus Laboratories can organise this for you if you don’t have access to an experienced genetic and registered health professional.

“Counselling” will include a questionnaire prior to your test and once your sample has been analysed your report will be discussed with you by one of Regenerus Laboratories genetic counsellors.

If your report shows that you have inherited either one or both faulty genes, it may be worth taking your report, along with the research article, to your GP or endocrinologist and asking for a trial of T3 to be added to your levothyroxine.

Please let us know how you get on by sending an email to enquiries@throiduk.org

To read more about the test and how to order it click here 

Thyroid UK receives a donation for each test ordered via this information.

Further information can be obtained from the following links:

Dr Damien Downing’s Report

Breakthrough Discovery: Need For T3 Could Be Genetic by Dr Gary Pepper

To read the Guidelines, “A Common Framework of Principles for direct-to-consumer genetic testing services”
go to: www.sashg.org/documents/HGC-UK-Policy-on-DTC-testing.pdf

Eurogentest - EuroGentest is a project funded by the European Commission

Recommendations for Genetic Counselling related to Genetic Testing:

Direct-to-consumer genomic testing from the perspective of the health professional: a systematic review of the literature:

Guidelines for health professionals about genetic testing, counselling and research in Europe:

Thyroid UK is a member of Genetic Alliance UK.
Genetic Alliance UK is the national charity of over 150 patient organisations supporting all those affected by genetic conditions - www.geneticalliance.org.uk/index.html


Thyroid UK will receive a donation for each test you order so you will not only be monitoring your thyroid health but you will also be supporting us.