This project is utilizing an efficient, established birth defect gene discovery pipeline that focuses on important birth defects associated with balanced chromosomal rearrangements. We are attempting to identify genes that are disrupted by the rearrangement breakpoints, and are testing the hypothesis that the genes disrupted by breakpoints are causal for the subject's phenotype. To test the validity of the candidate genes identified, two further strategies will be employed: (1) mutational analysis of phenotypically similar cases that do not involve chromosomal rearrangements, to search for intragenic mutations in the candidate gene, and (2) recapitulation of key aspects of the proband's phenotype in the mouse by targeted mutation or knockdown of the candidate gene. The endpoint for these analyses is to obtain conclusive evidence that the gene disrupted by chromosomal rearrangement in any given case is responsible for the associated birth defects, and to conduct an initial analysis of the gene's developmental function. To accomplish these goals, we will employ a robust accrual system to recruit cases of interest from both national outreach and from major commercial cytogenetic providers. The specific aims of this project are: (1) to ascertain cases involving balanced chromosomal rearrangements associated with disorders of craniofacial, ocular or renal development, and to map the rearrangement breakpoints; (2) to identify candidate genes disrupted by the breakpoints and to determine the relevant mutational mechanisms; (3) to establish causality for the candidate genes identified in Aim 2 by mutational analyses of phenotypically related human cases; (4) to further establish causality for the candidate genes identified in Aim 2 by using genetic means to recapitulate the phenotype in mouse, and to determine the gene’s developmental function.
