GENETIC ETIOLOGY OF NONSYNOMIC CLEFT PALATE

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Cleft lip and cleft palate are common birth defects affecting 1-2/1000 live births. It is apparent that genetic factors contribute significantly to their etiology. Most orofacial clefts are non- syndromic, isolated effects, which can be separated into two different phenotypes: (1) cleft lip with or without cleft palate (CL/P) and 2) cleft palate only (CPO). Both are genetically complex traits, which has limited the ability to identify disease loci or genes. Previous effects to determine the genetic etiology for non-syndromic clefts have relied on candidate gene approaches with most studies focused on CL/P. The overall objective of this and future projects is to identify disease loci and genes involved in non-syndromic CPO by employing new linkage strategies to study affected relative pairs and extended pedigrees. These approaches, which have yet been applied to CPO, are very powerful in that no prior knowledge about the involved biological processes or inheritance pattern is needed. The specific aim of this project is to ascertain 150 families with multiple members affected with CPO from the Shanghai region of China. An additional 100 CPO patients will be ascertained along with their parents for use in linkage disequilibrium analyses. This will be performed in collaboration with Dr. You-e Liu of the Zhabei Eye Hospital, Shanghai and Dr. Mary Marazita of the Cleft Palate Center, Pittsburgh, who have collaborated since Cleft Palate Clinic at the University of Pittsburgh Cleft Palate-Craniofacial Center to add to the 45 families already recruited through the efforts of there collaborative investigators. The scope of this project will be to evaluate candidate genes for CPO using both linkage and linkage disequilibrium analyses. The population of Shanghai, China is relatively homogeneous, which a unique quality that increases the power to map a disease loci and also facilitate the transition to physical mapping and gene identification. The strength of this study is the relatively large numbers of affected relative pairs that can be ascertained at multiple sites, thus increasing the overall power for the study to detect loci of even modest effect. It will be through projects such as this one, in which collaborations with researchers world wide have been established to apply a combination of genetic strategies, that disease loci for CPO will be identified. Ultimately, this will further the knowledge of normal and abnormal craniofacial development, such that therapies to prevent CPO can be developed.