Many biological phenomena are either invisible or only partially characterized when interrogated using standard analyses that average data across a bulk population of cells. Now, technological advances are providing unprecedented opportunities to analyse the complexities of biological systems at the single-cell level. High-throughput analyses of the genomes, transcriptomes and proteomes of single cells are yielding novel and important insights into diverse processes such as development, gene-expression dynamics, tissue heterogeneity and disease pathogenesis. In this Focus issue, we highlight the transformative potential of single-cell omics approaches.

In this Focus issue on microbial genomics, Nature Reviews Genetics explores the impact of high-throughput sequencing technologies on microbiology research and their emerging application in clinical practice.

Delivering genes or RNAs to cells and tissues, or correcting existing genes, is an approach with great potential to treat a range of diseases. Since its inception about 20 years ago, the field of gene-based therapies has met with considerable challenges and controversy. However, recent progress has helped to realize the initial promise of these approaches and several gene-based therapies have now achieved success in clinical trials.

The pace of stem cell research continues to accelerate, with rapid advances being made in diverse areas, from understanding the fundamentals of their biology to how these unique cells can give insights into the genetic and cellular causes of human disease. This joint Focus between Nature Cell BiologyandNature Reviews Geneticsreviews the latest developments, including the nature of pluripotency, methods for manipulating cell fate and how stem cells might be used in clinical and research applications.

A number of pressing, interrelated, global challenges face the human race in the 21st century: environmental change, population growth and a rapid decline in fossil fuel reserves. This Focus issue looks at ways in which genetics can be harnessed to address these problems, from crop genetic engineering for improved yields and economical biofuel production, to the genetic monitoring of effects of environmental change on the world's biodiversity.

Evolutionary developmental biology (evo–devo) attempts to integrate an understanding of developmental processes into the Modern Synthesis of genetics and evolution, which classically focused on how allele frequencies changed in populations. The web focus contains articles that look at the conceptual advances that evo–devo is offering to evolutionary biology as a whole, as well as articles that describe specific experimental evo–devo studies.

The fundamental roles of epigenetics in genome regulation make an understanding of mechanisms such as DNA methylation and histone modification an essential goal, both for basic and applied research. The topics covered in this web focus range from basic research in chromosome biology and gene regulation, to stem cell research, environmental epigenetic and cancer epigenomics, where exploring the role of epigenetics has the potential to lead to clinical advances.

Fields as disparate as population genetics, systems biology, mathematical modelling of development and transcription profiling rely on quantitative descriptions, and statistical analysis — once a concept foreign to mainstream genetics — is pervading every aspect of the field. The articles in this Focus untangle the complex issues in statistical analysis, and present the continually debated solutions and the authors' opinion on future trends.

This Focus issue stresses the need for more research on monogenic disorders and the unique opportunity they offer for developing treatments, from aiding drug target identification to a host of genetic medicines.

Welcome to the Nature Reviews Geneticsweb focus on the body plan - a selection of recently published Reviews on this topic.

Epigenetics — the study of heritable changes in gene expression or function that occur without a change in the DNA sequence itself — is proving to have an increasingly important role in both human development and disease, particularly cancer.

Repeat instability is a unique dynamic mutation mechanism that underlies many diseases characterised by muscular and neuronal degeneration, such as Huntington disease, Fragile X syndrome, Friedreich ataxia and spinocerebellar ataxias, to name but a few.