Project description:<p>Building upon our previous linkage and association studies, we will use whole exome sequencing studies of second and third degree affected relatives drawn from multiplex families. Our specific aims are: 1) To conduct whole exome sequencing on affected members (2° and 3° relatives) drawn from multiplex cleft families from a consortium to identify novel genes causing non-syndromic oral clefts; 2) To confirm and test the role of rare variants in these novel genes through confirmatory Sanger sequencing, plus linkage information using additional members available in these multiplex families. This whole exome sequencing approach will combine evidence from linkage studies and large scale sequencing to identify novel genes causing oral clefts in multiplex cleft families. </p>
Project description:By sequencing the exomes of distantly related individuals in multiplex families, rare mutational and structural changes to coding DNA can be characterized and their relationship to disease risk can be assessed. Recently, several rare single nucleotide variants (SNVs) were associated with an increased risk of nonsyndromic oral cleft, highlighting the importance of rare sequence variants in oral clefts and illustrating the strength of family-based study designs. However, the extent to which rare deletions in coding regions of the genome occur and contribute to risk of nonsyndromic clefts is not well understood. To identify putative structural variants underlying risk, we developed a pipeline for rare hemizygous deletions in families from whole exome sequencing and statistical inference based on rare variant sharing. Among 56 multiplex families with 115 individuals, we identified 53 regions with one or more rare hemizygous deletions. We found 45 of the 53 regions contained rare deletions occurring in only one family member. Members of the same family shared a rare deletion in only eight regions. We also devised a scalable global test for enrichment of shared rare deletions.