It's suggested that the most optimal profile are people under 35, but I don't think people over that age are automatically disqualified. It's just that the majority profile they are looking for contains males who are under 35.
Thank You For Making the Decision to Register for OneMatch
Joining the OneMatch Stem Cell and Marrow Network is simple. If you’re between the ages of 17 and 35 and in good general health, you’re eligible to sign up. You can start the registration process here.