Large-scale sequencing solves mystery of dust mite origins

House dust mites, those sneeze-inducing denizens of our mattresses and pillows, turn out to have a fascinating evolutionary history. Large-scale sequencing and phylogenetic analysis recently revealed that they evolved from parasitic mites, which in turn evolved from free-living animals in the larger family of arachnids that also includes spiders. It is not fun to think about these eight-legged mites munching on one’s sloughed skin, but the dust mite tells an interesting evolutionary tale, recently revealed via genome-scale comparative analysis. After testing 62 published hypotheses regarding the evolution of dust mites, researchers at the University of Michigan concluded that house dust mites evolved from the Psoroptidia, parasites that never leave the bodies of their hosts. Their immediate parasitic ancestors are livestock mange mites and ear mites living on dogs and cats. At some point, dust mites evolved to become free-living, a finding that runs counter to the long-held theory that obligate parasites don’t return to free-living forms. Once people moved indoors, our dust mite companions found a feast of keratin in shed human skin and hair. Published 15 February 2013 in Systematic Biology, the study may assist research into the immune-response-triggering properties of dust mites that cause allergic symptoms in humans. The research may also lend insight into the ability of dust mites to inhibit host immune responses and thus eventually lead to new treatment for these allergies. —Karyn Hede, News Editor

A GWAS shows that psychiatric disorders share genetic underpinnings

Five major psychiatric disorders—autism, attention deficit-hyperactivity disorder, bipolar disorder, major depressive disorder, and schizophrenia—share genetic risk factors, according to a large genome-wide association study (GWAS) published 27 February 2013 in The Lancet. The identified molecular risk factors include four loci located in regions of chromosomes 3p21 and 10q24, along with single-nucleotide polymorphisms (SNPs) in two genes encoding calcium channel blocker components. One of the genes, CACNA1, had previously been linked to bipolar disorder and schizophrenia. The extensive study, conducted by the Psychiatric Genomics Consortium, compared the genomes of 33,332 patients and 27,888 controls. In addition, the study demonstrated that 14 SNPs previously significantly associated with schizophrenia and bipolar disorder have broader phenotypic effects. Overall, calcium channel activity was shown to play an important role in the development of all five disorders. Because these psychiatric disorders are treated clinically as distinct disorders, the findings assist the goal of moving beyond descriptive syndromes in psychiatry toward identifying and treating the root cause of disease. In an accompanying commentary, Alessandro Serretti and Chiara Fabbri, specialists in psychiatric disorders at the University of Bologna, Italy, concluded that the study will contribute to prediction and prevention of psychiatric diseases and provides new molecular targets for the next generation of psychotropic drugs. —Karyn Hede, News Editor

Genetics in Medicine| Mission Statement

Genetics in Medicine is a monthly journal committed to the timely publication of:

  • Original reports which enhance the knowledge and practice of medical genetics

  • Strategies and innovative approaches to the education of medical providers at all levels in the realm of genetics

As the official journal of the American College of Medical Genetics and Genomics (ACMG), the journal will:

  • Provide a forum for discussion, debate and innovation concerning the changing and expanding role of medical genetics within the broader context of medicine

  • Fulfill our responsibility to the College membership through the publication of guidelines, policy statements and other information that enhances the practice and understanding of medical genetics

Finally, as genetics becomes increasingly important in the wider medical arena, we will be an accessible and authoritative resource for the dissemination of medical genetic knowledge to providers outside of the genetics community through appropriate reviews, discussions, recommendations and guidelines.