Do orofacial clefts represent different genetic entities?

OBJECTIVE: To contribute to the understanding of potential genetic differences between different cleft types. METHOD: Analysis of family history concerning cleft type and search for cleft-type-specific associations in candidate genes performed in 98 individuals from 98 families. RESULTS: In a given family, the cleft type of a second case was more often identical to the index case than expected by chance. Each type of cleft (cleft lip [CL], cleft lip and palate [CLP], cleft palate only [CP], and submucous cleft palate only [SMCP]) was associated with different genes. CONCLUSION: Family history indicates some specificity of cleft types. The observed phenotype-genotype associations were compatible with this interpretation in that significant associations occurred with disjoint sets of genes in each cleft type. These observations indicate that CL, CLP, CP, and SMCP might represent genetically different entities.