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This Week in PNAS: Nov 25, 2014

Editor's Note: Some of the articles described below are not yet available at the PNAS site, but they are scheduled to be posted some time this week.

In a study appearing online in the Proceedings of the National Academy of Sciences, a Turkish-led team describes a mutation in the mitochondrial serine protease-coding gene HTRA2 that can cause an inherited form of essential tremor, a movement disorder that may progress to Parkinson's disease. Starting from a six-generation family from Turkey that was frequently afflicted with essential tremor and/or Parkinson's disease, the researchers performed exome sequencing on three affected individuals to find the HTRA2 glitch. In those with two mutant alleles, tremors tended to appear earlier in life, progressing to Parkinson's disease when individuals reached middle age.

Researchers from Stanford University used a combination of microfluidics-based amplification and targeted sequencing to do single-cell profiling on almost 1,500 individual acute lymphoblastic leukemia (ALL) cells from six individuals with childhood ALL. After identifying genomic regions prone to heterogeneity through bulk sequencing on childhood ALL samples, the team did targeted sequencing on specific sequences, deletions, and single nucleotide variants in 1,479 individual tumor cells. The study's authors then used mutation patterns detected in single cells from each individual's tumor to identify co-dominant clones in each tumor. "Taken together," they write, "these data order the sequence of genetic events that underlie childhood ALL and provide a framework for understanding the development of the disease at single-cell resolution."

Finally, there's a look at systemic lupus erythematosus from a team based in China that did genomic and methylomic sequencing on blood plasma samples from two dozen individuals with the condition and 11 without. Among the differences the researchers detected in the blood of those SLE was an over-representation of very short DNA fragments, notable declines in DNA methylation density, shifts in representation by DNA from different parts of the genome — features that seemed to stem, in part, from enhanced immunoglobulin binding of DNA in the blood of those with the disease. The study's authors argue that such findings "may provide new molecular markers for SLE," while raising potential red flags for those interpreting non-invasive prenatal tests or circulating cancer DNA test results in those with SLE.

The Scan

Positive Framing of Genetic Studies Can Spark Mistrust Among Underrepresented Groups

Researchers in Human Genetics and Genomics Advances report that how researchers describe genomic studies may alienate potential participants.

Small Study of Gene Editing to Treat Sickle Cell Disease

In a Novartis-sponsored study in the New England Journal of Medicine, researchers found that a CRISPR-Cas9-based treatment targeting promoters of genes encoding fetal hemoglobin could reduce disease symptoms.

Gut Microbiome Changes Appear in Infants Before They Develop Eczema, Study Finds

Researchers report in mSystems that infants experienced an enrichment in Clostridium sensu stricto 1 and Finegoldia and a depletion of Bacteroides before developing eczema.

Acute Myeloid Leukemia Treatment Specificity Enhanced With Stem Cell Editing

A study in Nature suggests epitope editing in donor stem cells prior to bone marrow transplants can stave off toxicity when targeting acute myeloid leukemia with immunotherapy.