Volume 49 Issue 4, April 2017

The newly described de novo goat genome sequence is the most contiguous diploid vertebrate assembly generated thus far using whole-genome assembly and scaffolding methods. The contiguity of this assembly is approaching that of the finished human and mouse genomes and suggests an affordable roadmap to high-quality references for thousands of species.

A study of genetic variation in yeast has identified key quantitative trait loci (QTLs) that suppress the effects of variation at multiple other loci. These loci prove essential to accurately modeling yeast growth in response to different environments.

An international collaboration has assembled DNA samples and detailed phenotypic information from >13,000 individuals with a clinical diagnosis of either autism spectrum disorder (ASD) or intellectual disability/developmental delay (ID/DD). The application of molecular inversion probe technologies to sequence 208 candidate genes at scale in this impressive resource has identified a large set of plausibly causative mutations for these disorders.

Jérôme Salse and colleagues report a reconstruction of the most recent common ancestor of modern monocots and eudicots, which dates to the late Triassic era. Their results represent a resource for plant geneticists to extend findings from model species to crops.

Örjan Carlborg and colleagues analyze genotype and phenotype data from 4,390 yeast segregants from a cross between laboratory and vineyard strains to estimate how higher-order genetic interactions contribute to complex trait variation. They find networks of epistatic loci and show that accounting for these interactions leads to more accurate phenotypic predictions.

Mark Daly and colleagues use population reference samples to refine the role of de novo protein-truncating variants in neurodevelopmental disorders. They show that variants independently observed in population reference samples do not contribute substantively to neurodevelopmental risk, and they use a loss-of-function intolerance metric to identify a small subset of genes that contain the entire observed signal of associated de novo protein-truncating variants in these disorders.

Linda Richards, Paul Lockhart, Christel Depienne and colleagues identify heterozygous DCC mutations in four families and five sporadic individuals with agenesis of the corpus callosum (ACC). They report that DCC mutations result in variable dominant phenotypes with incomplete penetrance, including mirror movements and ACC associated with a favorable developmental prognosis.

Evan Eichler and colleagues use single-molecule molecular-inversion probes to sequence the coding and splicing regions of 208 candidate genes in more than 11,730 individuals with neurodevelopmental disorders. They report 91 genes with an excess of de novo or private disruptive mutations, identify 25 genes showing a bias for autism versus intellectual disability, and highlight a network associated with high-functioning autism.

Huda Zoghbi and colleagues report that loss of the ATXN1–CIC protein complex in the developing mouse forebrain results in hyperactivity and defects in learning and memory. Loss of Cic in specific brain regions causes social interaction defects, and patients with de novo CIC mutations present signs of hyperactivity, autism spectrum disorder and intellectual disability.

Grant Stewart, Andrew Jackson, Christopher Mathew, Fowzan Alkuraya and colleagues identify a novel replication fork protein, DONSON, which is important for maintaining genome stability. Mutations in DONSON cause microcephalic dwarfism and lead to stalled replication forks and DNA damage.

Eileen Furlong, Oliver Stegle and colleagues quantify transcriptional start site (TSS) usage across 81 Drosophila lines, identifying genetic variants that affect transcript levels or the distribution of the TSS within a promoter. Using single-cell measurements, they show that variants modulating promoter shape often increase expression noise.

Melanie Bahlo and colleagues perform the first genome-wide association analysis for macular telangiectasia type 2. They identify three significant loci and report on a potential connection to the glycine/serine metabolism pathway.

Amalio Telenti, Craig Venter and colleagues report common, low-frequency and rare variants associated with blood metabolite levels using whole-genome sequencing and comprehensive metabolite profiling in 1,960 individuals. They identify 246 metabolites whose levels are associated with genetic variation at 101 loci.

Xianlong Zhang, Keith Lindsey and colleagues report a population genomic analysis of Upland cotton (Gossypium hirsutum) that identifies 93 potential domestication-sweep regions and 19 candidate loci for fiber-quality-related traits. Their analysis provides evidence for asymmetric subgenome selection for long white fibers in cultivated cotton.

Bjarni Halldorsson, Kari Stefansson and colleagues analyze genomic data from 15,219 Icelanders to identify non-repetitive sequences that are missing from the reference genome. They describe 3,791 breakpoint-resolved sequence variants and find overlap with GWAS markers as well as the presence of a proportion of these variants in the chimpanzee genome.

Raul Rabadan, Woong-Yang Park, Do-Hyun Nam and colleagues examine the genomic and transcriptomic profiles of tumors from 52 patients with glioblastoma using both bulk and single-cell analyses. They find that tumors that are isolated from distinct locations or at different times are seeded from different clones, suggesting the need for multisector biopsies.

Shamil Sunyaev, Chris Cotsapas and colleagues present a joint likelihood framework for determining the statistical evidence of shared genetic effects of overlapping disease-associated loci and expression quantitative trait loci (eQTLs). They find evidence for shared genetic effects at 25% of eQTL–autoimmune disease locus pairs.

Timothy Yu and colleagues report that biallelic mutations in DCC cause a developmental syndrome characterized by widespread disruption of midline-bridging neuronal commissures, including agenesis of the corpus callosum, absence of hippocampal and anterior commissures, and ventral midline brainstem malformations. Clinical manifestations include horizontal gaze palsy, mirror movements, scoliosis and intellectual disability.

Christian Schaaf, Yaping Yang and colleagues report that germline mutations in ABL1, which is best known as part of the fusion gene BCR-ABL1 on the Philadelphia chromosome, cause an autosomal dominant disorder characterized by heart disease, skeletal abnormalities and failure to thrive. They find that these mutations increase the kinase activity of ABL1, establishing another example of mutations in a proto-oncogene leading to developmental defects.

Adam Siepel and colleagues report a new computational method, LINSIGHT, that combines evolutionary conservation and functional genomic information to predict the fitness consequences of noncoding mutations in the human genome. They use LINSIGHT to show that fitness consequences of enhancer mutations depend on tissue and cell type specificity and promoter constraints.

Stuart Orkin, Daniel Bauer and colleagues present DNA Striker, a computational tool to design variant-aware saturating-mutagenesis screens with multiple CRISPR-associated nucleases. They apply their methodology to the HBS1L-MYB intergenic region, which is associated with red-blood-cell traits, and identify putative regulatory elements that control MYB expression.

Kun Zhang and colleagues present a metric called methylation haplotype load (MHL) that quantifies methylation patterns within blocks of tightly linked CpG dinucleotides. They show that the MHL can distinguish samples from different human somatic tissues and that it can be used to improve detection of cancer-derived circulating DNA and identify its tissue of origin.

Adam Phillippy, Curtis Van Tassell, Timothy Smith and colleagues present a new reference genome assembly for the domestic goat using a pipeline that improves contiguity of the assembly by more than 250-fold. The pipeline uses a combination of short- and long-read sequencing, optical mapping, and chromatin interaction mapping.