Researchers from the US and Israel took a look at genetic diversity in clinical isolates of Candida albicans, an often harmless fungal species that can cause serious infections. Using genome sequencing and multilocus sequence typing, the team characterized 21 C. albicans isolates, including 14 found in bloodstream infections and seven isolated from oral or vaginal sites. From this data, the study's authors not only tracked down sequence variants and aneuploid sites in the C. albicans genomes, but also identified apparent relationships between genetic changes and fungal phenotype. Among them: an EFG1 gene mutation that seems to bump up fungal fitness. "Our analysis … reveals intra-species genetic and phenotypic differences in C. albicans," they write, "and delineates a natural mutation that alters the balance between commensalism and pathogenicity."
Exome sequencing on individuals with intellectual disability and unusual skull, skeleton, and tooth features led researchers from Germany and elsewhere to BRF1 gene mutations behind a newly described autosomal recessive neurodevelopmental syndrome. By sequencing one or more affected individuals from three families that had children with similar developmental symptoms, the team tracked down missense BRF1 mutations that were subsequently shown to alter RNA polymerase III binding at target genes, leading to lower-than-usual activity of some proteins.
Finally, a team from the University of California, Berkeley, describes a computational method it developed for inferring past human population sizes as well as mutation rates at particular genomic loci. The method considers so-called sample frequency spectrum, authors of the study explain, a number based on single nucleotide variant and mutant allele frequency data. Using both real and simulated population data, the researchers showed that this approach could accurately retrace past human population patterns, including instances of exponential growth — particularly when using large sample sets to look for recent jumps in population size.