Volume 10 Issue 11, November 2009

Although humans are genetically similar, marked geographic patterns exist for many heritable traits. The investigation of spatial patterns at loci under selection can address fundamental questions about geographically variable traits in humans and give new insights into human adaptation.

Inherited mutations in the nucleotide excision DNA repair pathway cause an unusually diverse range of clinical abnormalities; even mutations in the same gene can cause markedly different phenotypes. Recent structural, genetic and clinical studies are helping to explain this variability.

Dozens of new genes with causal roles in motor neuron diseases have recently been identified, which has moved the field beyond the previous focus on superoxide dismutase 1 mutations. These findings implicate several additional pathways in motor neuron diseases, including RNA processing, axonal transport and mitochondrial function.

The genetic basis of inbreeding depression and of the related phenomenon, heterosis, has been a puzzle for many decades. Based on recent studies in many species, the authors argue that both phenomena are predominantly caused by the presence of recessive deleterious mutations in populations.

Increasing evidence suggests that animal sexual dimorphisms are produced by the combined action of transcriptional effectors of sex-determination pathways and other transcription factors oncis-regulatory elements. These findings have led to new insights into how differences between sexes evolve.

DNA methylation is a somatically heritable epigenetic mark that must be faithfully maintained through cell division. This re-examination of the evidence relating to how DNA methylation is maintained leads the authors to propose a revised model for this important biological process.