Genetic Studies in the Nigerian Population Implicate an MSX1 Mutation in Complex Oral Facial Clefting Disorders

Background: Orofacial clefts are the most common malformations of the head and neck, with a worldwide prevalence of 1 in 700 births. They are commonly divided into CL(P) and CP based on anatomic, genetic, and embryologic findings. A Nigerian craniofacial anomalies study (NigeriaCRAN) was set up in 2006 to investigate the role of gene-environment interaction in the origin of orofacial clefts in Nigeria. Subjects and Methods: DNA isolated from saliva from Nigerian probands was used for genotype association studies and direct sequencing of cleft candidate genes: MSX1, IRF6, FOXE1, FGFR1, FGFR2, BMP4, MAFB, ABCA4, PAX7, and VAX1, and the chromosome 8q region. Results: A missense mutation A34G in MSX1 was observed in nine cases and four HapMap controls. No other apparent causative variations were identified. Deviation from Hardy Weinberg equilibrium (HWE) was observed in these cases (p=.00002). A significant difference was noted between the affected side for unilateral CL (p=.03) and bilateral clefts and between clefts on either side (p=.02). A significant gender difference was also observed for CP (p=.008). Conclusions: Replication of a mutation previously implicated in other populations suggests a role for the MSX1 A34G variant in the development of CL(P).