Animal models

Correction of fragile X syndrome in mice. Dölen, G. et al. Neuron 56, 955–962 (2007)

Fragile X syndrome (FXS) results from transcriptional silencing of the FMR1 gene, but how this defect results in disease is unclear. These authors tested the hypothesis that key FXS symptoms are caused by a loss of regulation of the metabotropic glutamate receptor mGluR5. Consistent with this theory, several phenotypes that parallel human neurological and psychiatric FXS symptoms were rescued in FMR1-null mice that were also engineered to give a 50% reduction in mGluR5 expression. This finding suggests new avenues for developing therapies for FXS.

Evolution

cis -regulatory changes in Kit ligand expression and parallel evolution of pigmentation in sticklebacks and humans. Miller, C. T. et al. Cell 131, 1179–1189 (2007)

This paper shows that regulatory changes in the Kit ligand (Kitlg) gene contribute to variation in pigmentation in sticklebacks and humans, suggesting that similar genetic changes might underlie morphological evolution across vertebrates. By using genome-wide linkage mapping in sticklebacks, the authors identified mutations in Kitlg that are also associated with reduced pigmentation in freshwater populations. Strong signatures of selection around human KITLG and the results of admixture mapping suggest that similar genetic changes influence human skin colour.

Disease genetics

Clustered environments and randomized genes: a fundamental distinction between conventional and genetic epidemiology. Davey Smith, G. et al. PLoS Med. 4, e352 (2007)

This study demonstrates, for the first time, the validity of using Mendelian randomization in epidemiological studies. In this approach, a genetic variant that is associated with a non-genetic risk factor is used to determine whether the latter has a causal role in disease risk. Using data from an established prospective cohort study, the authors confirm that genetic associations are far less susceptible to confounding (in which a factor appears to be associated with disease risk owing to its correlation with other causal factors) than are non-genetic factors.

Genomics

The Physcomitrella genome reveals evolutionary insights into the conquest of land by plants. Rensing, S. A. et al. Science 319, 64–69 (2008)

The first Bryophyte genome sequence has been reported. Because Bryophytes are remnants of early diverging lineages of land plants, they are important in evolutionary studies — most notably for studying the conquest of land by plants. The sequence revealed that this event was associated with an increase in gene-family complexity, acquisition of genes for terrestrial stress tolerance, and the development of auxin and abscisic acid signalling, which coordinates multicellular growth and responses to dehydration.