Project description:The <a href="https://www.commonfund.nih.gov/KidsFirst">Gabriella Miller Kids First Pediatric Research Program</a> (Kids First) is a trans-NIH effort initiated in response to the <a href="https://www.govtrack.us/congress/bills/113/hr2019">2014 Gabriella Miller Kids First Research Act</a> and supported by the NIH Common Fund. This program focuses on gene discovery in pediatric cancers and structural birth defects and the development of the Gabriella Miller Kids First Pediatric Data Resource (Kids First Data Resource). Both childhood cancers and structural birth defects are critical and costly conditions associated with substantial morbidity and mortality. Elucidating the underlying genetic etiology of these diseases has the potential to profoundly improve preventative measures, diagnostics, and therapeutic interventions. WGS and phenotypic data from this study are accessible through dbGaP and <a href="https://kidsfirstdrc.org">kidsfirstdrc.org</a>, where other Kids First datasets can also be accessed. The Kids First study of nonsyndromic orofacial cleft birth defects (OFCs) is a whole genome sequencing study of 415 White parent-case trios drawn from ongoing collaborations led by Dr. Mary L. Marazita of the University of Pittsburgh Center for Craniofacial and Dental Genetics, including collaborations with Dr. George Wehby of the University of Iowa, Dr. Jacqueline Hecht of the University of Texas, and Dr. Terri Beaty of Johns Hopkins University. Sequencing was done by the Washington University McDonell Genome Institute. The case in each of the Kids First trios has cleft lip (CL, Figure A), cleft palate (CP, Figure B), or both (CL+CP, Figure C): <img src="GetImage.cgi?study_id=phs001420&image_name=GMKFCleft.jpg"/> OFCs are genetically complex structural birth defects caused by genetic factors, environmental exposures, and their interactions. OFCs are the most common craniofacial anomalies in humans, affecting approximately 1 in 700 newborns, and are one of the most common structural birth defects worldwide. On average a child with an OFC initially faces feeding difficulties, undergoes 6 surgeries, spends 30 days in hospital, receives 5 years of orthodontic treatment, and participates in ongoing speech therapy, leading to an estimated total lifetime treatment cost of about $200,000. Further, individuals born with an OFC have higher infant mortality, higher mortality rates at all other stages of life, increased incidence of mental health problems, and higher risk for other disorders (notably including breast, brain, and colon cancers). Prior genome-wide linkage and association studies have now identified at least 18 genomic regions likely to contribute to the risk for nonsyndromic OFCs. Despite this substantial progress, the functional/pathogenic variants at OFC-associated regions are mostly still unknown. Because previous OFC genomic studies (genome-wide linkage, genome-wide association studies (GWAS), and targeted sequencing) are based on relatively sparse genotyping data, they cannot distinguish between causal variants and variants in linkage disequilibrium with unobserved causal variants. Moreover, it is unknown whether the association or linkage signals are due to single common variants, haplotypes of multiple common variants, clusters of multiple rare variants, or some combination. Finally, we cannot yet attribute specific genetic risk to individual cases and case families. Therefore, the goal of the current study is to identify specific OFC risk variants in Whites by performing whole genome sequencing of parent-case trios.

Project description:Orofacial clefts are the most common form of congenital craniofacial malformations worldwide. The etiology of these birth defects is multifactorial, involving genetic and environmental factors. In most cases, however, the underlying causes remain unexplained, precluding molecular understanding of disease mechanisms. Here, we integrated genome-wide association data, targeted re-sequencing of case and control cohorts, cell type-specific epigenomic profiling, and genome architecture analyses, to functionally and molecularly dissect a genomic locus associated with an increased risk of non-syndromic orofacial cleft. We found that common and rare risk variants associated with orofacial cleft intersect with a conserved enhancer (e2p24.2) that becomes activated in cranial neural crest cells—the embryonic cell type responsible for sculpting the craniofacial complex. We mapped e2p24.2 long-range interactions to a topologically associated domain harboring MYCN and DDX1 and demonstrated that both MYCN and DDX1 are required for craniofacial development in chicken embryos. We found that e2p24.2 regulates the expression of MYCN, but not DDX1, in cranial neural crest cells. In turn, DDX1 is a target of the MYC family of transcription factors and a component of the tRNA splicing complex. The loss of DDX1 in cranial neural crest cells resulted in the accumulation of unspliced tRNA fragments, depletion of the mature pool of intron-containing tRNAs, and ribosome stalling at codons decoded by these tRNAs. These effects were accompanied by defects in both global protein synthesis and cranial neural crest cell migration. We further showed that the induction of tRNA fragments is sufficient to disrupt craniofacial development. Together, these results uncovered a molecular mechanism in which impaired tRNA splicing affects neural crest and craniofacial development and positioned MYCN, DDX1, and tRNA processing defects as risk factors in the pathogenesis of orofacial clefts.

Project description:The <a href="https://www.commonfund.nih.gov/KidsFirst">Gabriella Miller Kids First Pediatric Research Program</a>) (Kids First) is a trans-NIH effort initiated in response to the <a href="https://www.govtrack.us/congress/bills/113/hr2019">2014 Gabriella Miller Kids First Research Act</a> and supported by the NIH Common Fund. This program focuses on gene discovery in pediatric cancers and structural birth defects and the development of the Gabriella Miller Kids First Pediatric Data Resource (Kids First Data Resource). Both childhood cancers and structural birth defects are critical and costly conditions associated with substantial morbidity and mortality. Elucidating the underlying genetic etiology of these diseases has the potential to profoundly improve preventative measures, diagnostics, and therapeutic interventions. All of the WGS and phenotypic data from this study are accessible through dbGaP and <a href="https://kidsfirstdrc.org/">https://kidsfirstdrc.org</a>, where other Kids First datasets can also be accessed. The Kids First study of nonsyndromic orofacial cleft (OFC) birth defects in Latin American families is a whole genome sequencing study of 283 Latin-American parent-case trios drawn from ongoing collaborations led by Dr. Mary L. Marazita of the University of Pittsburgh Center for Craniofacial and Dental Genetics, and including a collaboration with Dr. Lina Moreno Uribe and Dr. Andrew Lidral of the University of Iowa. All families were ascertained through the Clinica Noel where patients with OFCs receive care from the Antioquia University School of Dentistry in Medellin, Colombia (key on-site colleagues included Dr. Luz Consuelo Valencia-Ramirez and Dr. Mauricio Arcos-Burgos). Genetic studies have shown that this population is comprised of an admixture of immigrant male Caucasians (mainly Spaniards and Basques) and native Amerindian females. Every subject has had a genetic evaluation, including a pedigree analysis for a family history of clefting and other birth defects, a pregnancy history for environmental exposures, and a complete physical exam to rule out suspected or known syndromes or environmental phenocopies. Sequencing was done by the Broad Institute sequencing center funded by the Kids First program (grant number U24-HD090743). The case in each of the Kids First OFC trios has cleft lip (CL, Figure A below), cleft palate (CP, Figure B), or both (CL+CP, Figure C): <img src="GetImage.cgi?study_id=phs001420&image_name=GMKFCleft.jpg"/> OFCs are genetically complex structural birth defects caused by genetic factors, environmental exposures, and their interactions. OFCs are the most common craniofacial anomalies in humans, affecting approximately 1 in 700 newborns, and are one of the most common structural birth defects worldwide. On average a child with an OFC initially faces feeding difficulties, undergoes 6 surgeries, spends 30 days in hospital, receives 5 years of orthodontic treatment, and participates in ongoing speech therapy, leading to an estimated total lifetime treatment cost of about $200,000. Further, individuals born with an OFC have higher infant mortality, higher mortality rates at all other stages of life, increased incidence of mental health problems, and higher risk for other disorders (notably including breast, brain, and colon cancers). Prior genome-wide linkage and association studies have now identified at least 18 genomic regions likely to contribute to the risk for nonsyndromic OFCs. Despite this substantial progress, the functional/pathogenic variants at OFC-associated regions are mostly still unknown. Because previous OFC genomic studies (genome-wide linkage, genome-wide association studies (GWAS), and targeted sequencing) are based on relatively sparse genotyping data, they cannot distinguish between causal variants and variants in linkage disequilibrium with unobserved causal variants. Moreover, it is unknown whether the association or linkage signals are due to single common variants, haplotypes of multiple common variants, clusters of multiple rare variants, or some combination. Finally, we cannot yet attribute specific genetic risk to individual cases and case families. Therefore, the goal of the current study is identify specific OFC risk variants in Latin American families by performing whole genome sequencing of parent-case trios.

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Kids First: Genomic Studies of Orofacial Cleft Birth Defects

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