The Changing Map of the Sickle Cell Gene in Kenya.

In a ten year prospective records survey we received reports of sickle cell anemia (SCA) from ethnic groups which initially had no sickle cell trait (SCT) in Kenya. A follow up study was done in 2000 using alkaline Hb-electrophoresis to reassess the current status of SCT in comparison with a study reported in the 1950’s. We found that of the initially unaffected groups, SCT was 8% in the sabaot, 6% in the Taita, 3% in the inland (Mt. Kenya) Kikuyu, 1% in the Turkana, but still absent in the Somali. There was also a shift in %-ages from the 1950 survey in tribes with SCT: 33% in the Suba in stead of 28%, and 22% in the Kambe instead of 35%. We also noted a remarkable difference between cosmopolitan and rural populations in two SCT endemic areas: 15% in Kisumu city against 28% rural neighborhood and 15% in Bungoma town against 21% in its rural population. It appears that sickle cell (HbS) gene distribution and spread is changing in Kenya and that this trend most likely applies to the rest of Africa as well. The findings might be useful in genetic counseling as well as for diagnosis of SCA on clinical grounds in ethnic groups among whom SCA was hitherto considered to be absent.