If one have both, you normally say this person has scz. In our organisation we talk about sickle cell disease and not anemia, because that is rare and does not say anything about crises. Disease also not, but that word includes all. Most SCD patients have hbSS (severe case) or hbSC (mild case; if not zero complaints) Both thalassemia and scd are recessive dieseases. There are less transplants done on scd patients then thals. But, and you may corrected me, you see more and more transplants done by young scd patients in the USA.
From a study done in Rotterdam we know there are lots of scd patients. It's even so much that I do not dare to repeat it here. Thal and SCZ has been taken to the Guthrie test since 2007. Sometimes it is still not catched by this. But a Guthrie test won't stop the growing of szd nor thal in the Netherlands. There's almost no pre birth testing, let alone pre marriage testing.
There are indeed more anemias who need transfusion, but, trust me, they are not so well organised or informed as others. Also PNH is treated with rituximab, DBA by prednison and fanconi anemia is just too evi*l. I have been at a Dutch conference for PNH, DBA, AA and more rare. I have heard stories about people who have had more than 50 blood transfusions but never have done any form of chelation.(* and recent lots of research opened and publiced)
So, what I want to say the Thal PLUS SCD are leaders in the world. You are very lucky. I am looking forward to May and I think we wil hear a lot of new developments in the SCD area.