In this week's Nature Genetics, an international research team presents two studies identifying new genetic loci linked to intelligence and neuroticism. In the first paper, the researchers perform a genome-wide association study of nearly 450,000 individuals to uncover 599 genes associated with neuroticism. They also report two genetically distinguishable subclusters, one relating to depressed affect and the other to worry, "suggesting distinct causal mechanisms for subtypes of individuals." In the second study, the researchers conduct a GWAS of about 250,000 people to find 190 loci and more than 1,000 specific genes associated with intelligence. They also report data pointing to a protective effect of intelligence for Alzheimer's disease and ADHD. "These results are a major step forward in understanding the neurobiology of cognitive function, as well as genetically related neurological and psychiatric disorders," the authors write. GenomeWeb has more on these studies, here.
And in Nature Methods, a Linköping University-led group of researchers describe a key problem with DNA immunoprecipitation followed by sequencing (DIP-seq) — a common enrichment method for profiling DNA modifications in mammalian genomes — and offer an approach to address the issue. According to the authors, the results of independent DIP-seq studies often show considerable variation between profiles of the same genome and between profiles obtained by alternative methods. The researchers show that these differences are largely a result of the intrinsic affinity of IgG for short unmodified DNA repeats, and conclude that "both matched input and IgG controls are essential in order for the results of DIP-based assays to be interpreted correctly." They further state that complementary, non-antibody-based techniques should be used to validate DIP-based findings.