testosterone isnt composed of DHT, test is test, which is converted to DHT via 5-AR. They are 2 diff hormones.....kind like test is converted to estro....
Test isnt COMPOSED of anything but H, C, O atoms to make the test hormone.
DHT is important in erectile issues......it might play a small part in muscular hypertrophy since it is anabolic, but MUCH less than test.......your gains wont suffer, you will be helping your prostate and hairline though......you might see erectile issues, but you will probly be ok.
Taken from wikipedia article on dht (if can believe it):
"DHT has been shown to be deactivated in skeletal muscle through the actions of 3-alpha hydroxysteroid dehydrogenase and therefore does not have a significant effect on muscle hypertrophy."