Distribution of orofacial clefts and frequent occurrence of an unusual cleft variant in the Rift Valley of Kenya.

Objective: To investigate the pattern and distribution of nonsyndromic orofacial clefts among patients in the Rift Valley region of northwestern Kenya.

Methods: Subjects were categorized anatomically for occurrence of an atypical cleft lip variant (ACL), typical cleft lip (CL), cleft lip and palate (CLP), or cleft palate (CP), and family history of orofacial clefts. Tribal ethnicity data were obtained from both cleft and noncleft clinic attendees.

Results: There were 194 patients with CL (52.7%), 153 with CLP (41.6%), and 21 with CP (5.7%). CL constitutes a greater fraction of orofacial clefts in the Rift Valley region than reported elsewhere in Africa, principally due to frequent occurrence of ACL (52.5% of all CL). Among noncleft clinic attendees there was a lower fraction of Bantu and larger fraction of Nilotic-Paranilotic tribal ethnicity than in Kenya overall. In contrast, among patients with orofacial clefts there was significant underrepresentation of Bantu and overrepresentation of Nilotic-Paranilotic tribes, particularly Kalenjin. Patients of Kalenjin origin had a much higher rate of positive family history of orofacial clefts than Bantu patients.

Conclusions: There is an unusual anatomic distribution of orofacial clefts in the Kenya Rift Valley, with frequent occurrence of an atypical CL variant. Our findings indicate that Bantu tribes have lower risk of orofacial clefts than Nilotic-Paranilotic tribes, possibly due to inherited genetic differences, perhaps accounting for the relatively low prevalence of orofacial clefts through much of Africa.