Project description:Orofacial clefts are one of the most common birth defects, affecting 1-2 per 1000 births, and have a complex etiology. High-resolution array-based comparative genomic hybridization has increased the ability to detect copy number variants that can be causative for complex diseases such as cleft lip and/or palate. Utilizing this technique on 97 non-syndromic cleft lip and palate cases and 43 cases with cleft palate only, we identified a heterozygous deletion of Isthmin 1 in one affected case, as well as a deletion in a second case which removes putative 3' regulatory information. Isthmin 1 is a strong candidate for clefting as it is expressed in orofacial structures derived from the first branchial arch and is also in the same synexpression group as fibroblast growth factor 8 and sprouty RTK signaling antagonist 1a and 2, all of which have been associated with clefting. Copy number variants affecting Isthmin 1 are exceedingly rare in control populations, and Isthmin 1 scores as a likely haploinsufficiency locus. Confirming its role in craniofacial development, knockdown or CRISPR/Cas9-generated mutation of isthmin 1 in Xenopus laevis resulted in mild to severe craniofacial dysmorphologies, with several individuals presenting with median clefts. Moreover, knockdown of isthmin 1 produced decreased expression of LIM homeobox 8, itself a gene associated with clefting, in regions of the face that pattern the maxilla. Our study demonstrates a successful pipeline from copy number variant identification of a candidate gene to functional validation in a vertebrate model system and reveals Isthmin 1 as both a new human clefting locus as well as a key craniofacial patterning gene.
Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven ‘hotspots,’ seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a ‘fertile’ subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility.
Project description:Genetic analysis of gene expression level is a promising approach for characterizing candidate genes that are involved in complex economic traits such as meat quality. In the present study, we conducted expression quantitative trait loci (eQTL) and allele-specific expression (ASE) analyses based on RNA-sequencing (RNAseq) data from the longissimus muscle of 189 Duroc × Luchuan crossed pigs in order to identify some candidate genes for meat quality traits. Using a genome-wide association study based on a fixed linear model, we identified 7,192 cis-eQTL corresponding to 2,098 cis-genes (p ≤ 1.33e-3, FDR ≤ 0.05) and 6,400 trans-eQTL corresponding to 863 trans-genes (p ≤ 1.13e-6, FDR ≤ 0.05). ASE analysis using RNAseq SNPs identified 9,815 significant ASE-SNPs in 2,253 unique genes. Integrative analysis between the cis-eQTL and ASE target genes identified 540 common genes, including 33 genes with expression levels that were correlated with at least one meat quality trait. Among these 540 common genes, 63 have been reported previously as candidate genes for meat quality traits, such as PHKG1 (q-value = 1.67e-6 for the leading SNP in the cis-eQTL analysis), NUDT7 (q-value = 5.67e-13), FADS2 (q-value = 8.44e-5), and DGAT2 (q-value = 1.24e-3).This study provides valuable information on the genetics of gene expression in porcine skeletal muscle. The characterized cis-genes and ASE genes, combined with the correlations between gene expression level and meat quality traits will be useful to prioritize candidate genes in further studies.
Project description:To characterize the genetic basis of hybrid male sterility in detail, we used a systems genetics approach, integrating mapping of gene expression traits with sterility phenotypes and QTL. We measured genome-wide testis expression in 305 male F2s from a cross between wild-derived inbred strains of M. musculus musculus and M. m. domesticus. We identified several thousand cis- and trans-acting QTL contributing to expression variation (eQTL). Many trans eQTL cluster into eleven M-bM-^@M-^Xhotspots,M-bM-^@M-^Y seven of which co-localize with QTL for sterility phenotypes identified in the cross. The number and clustering of trans eQTL - but not cis eQTL - were substantially lower when mapping was restricted to a M-bM-^@M-^XfertileM-bM-^@M-^Y subset of mice, providing evidence that trans eQTL hotspots are related to sterility. Functional annotation of transcripts with eQTL provides insights into the biological processes disrupted by sterility loci and guides prioritization of candidate genes. Using a conditional mapping approach, we identified eQTL dependent on interactions between loci, revealing a complex system of epistasis. Our results illuminate established patterns, including the role of the X chromosome in hybrid sterility. Gene expression was measured in whole testis in males aged 70(M-BM-15) days. Samples include 294 WSB/EiJ x PWD/PhJ F2s, 11 PWD/PhJ x WSB/EiJ F2s, 8 WSB/EiJ, 8 PWD/PhJ, 6 PWD/PhJ x WSB/EiJ F1s and 4 WSB/EiJ x PWD/PhJ F1s.
Project description:Facial features identify individuals, but the mechanisms shaping the human face remain elusive. Orofacial clefting (OFC), the most common craniofacial abnormality, results from failed fusion of the facial prominences, partly caused by persistence of the cephalic epithelium. Using mouse models to guide our studies, here we uncover the identity, behaviors, and molecular blueprints of a novel craniofacial epithelial population, Zippering Lambda (ZL), similarly characterized by cell cycle arrest in mouse and human embryos. Remarkably, in Pbx1/2 and p63 mutant mice with OFC cell cycle is unleashed in ZL epithelium. Intersecting ZL-enriched genes with human OFC whole-genome sequencing datasets identifies ZFHX3 variants in affected individuals and cephalic epithelial Zfhx3 deletion results in murine OFC. Our findings further demonstrate that ZFHX3 and PBX1 synergistically regulate cell cycle inhibitor genes acting within a complex in embryonic faces. Collectively, we deconstruct new mechanisms that pattern the face, connecting cell cycle arrest to developmental tissue fusion.
Project description:Facial features identify individuals, but the mechanisms shaping the human face remain elusive. Orofacial clefting (OFC), the most common craniofacial abnormality, results from failed fusion of the facial prominences, partly caused by persistence of the cephalic epithelium. Using mouse models to guide our studies, here we uncover the identity, behaviors, and molecular blueprints of a novel craniofacial epithelial population, Zippering Lambda (ZL), similarly characterized by cell cycle arrest in mouse and human embryos. Remarkably, in Pbx1/2 and p63 mutant mice with OFC cell cycle is unleashed in ZL epithelium. Intersecting ZL-enriched genes with human OFC whole-genome sequencing datasets identifies ZFHX3 variants in affected individuals and cephalic epithelial Zfhx3 deletion results in murine OFC. Our findings further demonstrate that ZFHX3 and PBX1 synergistically regulate cell cycle inhibitor genes acting within a complex in embryonic faces. Collectively, we deconstruct new mechanisms that pattern the face, connecting cell cycle arrest to developmental tissue fusion.