When you take a medicine (or drug), your body needs to find a way to use it.  Some proteins in your body break down (or metabolize) medicines.  Breaking down a medicine can make it more active or less active, based on what kind of medicine you are taking.  If your body breaks down a medicine too quickly or too slowly, this may make the medicine not work as well.  It may also cause a side effect.

The CYP3A5 gene tells your body how to make a protein.  It is the job of the CYP3A5 protein to break down certain medicines.  An example of this medicine is tacrolimus. This medicine is used after transplants and to treat certain skin diseases.

This is 1 medicine that we know of right now that is impacted by CYP3A5 gene test results.  Medical experts keep finding new data about which medicines are affected by gene test results.

By testing your DNA, we can find DNA differences.  This can help us to see how well the proteins in your body work to break down certain medicines. 

The results of your CYP3A5 gene test put you into 1 of 3 groups:

• Normal metabolizer: People in this group are likely to have normal working CYP3A5 proteins.
• Intermediate metabolizer: People in this group may have reduced activity of CYP3A5 proteins. 
• Poor metabolizer: People in this group may have very little or no active CYP3A5 protein. 

The results of this test can help your doctor choose the right medicine and dose for you.