Hmmm, in 2003, I think Keshishian was part of the USC group, though there may have been little or no follow up. I find it difficult to believe that 49/50 who had the DS 18 years ago would have died without that being noticed - many may simply have been lost to follow up.
Also, IIRC, the USC hospital IS where the early bariatric surgeries were done. At that time, Gary Anthone was also part of the practice. Katkouda (?) and his antipathy towards the DS drove Keshishian and Anthone away.