As dictated by MRC policy , Professor and Mrs. Serjeant retired from the Sickle Cell Unit in September 1999 .
Professor continues to work as Chairman of the Sickle Cell Trust ( Jamaica ) .
As dictated by MRC policy , Professor and Mrs. Serjeant retired from the Sickle Cell Unit in September 1999 , but he continues to work as Chairman of the Sickle Cell Trust ( Jamaica ) .