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White blood cell count (WBC) is unique among identified inflammatory predictors of chronic disease in that it is routinely measured in asymptomatic patients in the course of routine patient care. We led a genome-wide association analysis to identify variants associated with WBC levels in 13,923 subjects in the electronic Medical Records and Genomics (eMERGE) Network. We identified two regions of interest that were each unique to subjects of genetically determined ancestry to the African continent (AA) or to the European continent (EA). WBC varies among different ancestry groups. Despite being ancestry specific, these regions were identifiable in the combined analysis. In AA subjects, the region surrounding the Duffy antigen/chemokine receptor gene (DARC) on 1q21 exhibited significant association (p value = 6.71e–55). These results validate the previously reported association between WBC and of the regulatory variant rs2814778 in the promoter region, which causes the Duffy negative phenotype (Fy−/−). A second missense variant (rs12075) is responsible for the two principal antigens, Fya and Fyb of the Duffy blood group system. The two variants, consisting of four alleles, act in concert to produce five antigens and subsequent phenotypes. We were able to identify the marginal and novel interaction effects of these two variants on WBC. In the EA subjects, we identified significantly associated SNPs tagging three separate genes in the 17q21 region: (1) GSDMA, (2) MED24, and (3) PSMD3. Variants in this region have been reported to be associated with WBC, neutrophil count, and inflammatory diseases including asthma and Crohn’s disease.

The National Center for Biotechnology Information has created the dbGaP public repository for individual-level phenotype, exposure, genotype and sequence data and the associations between them. dbGaP assigns stable, unique identifiers to studies and subsets of information from those studies, including documents, individual phenotypic variables, tables of trait data, sets of genotype data, computed phenotype-genotype associations, and groups of study subjects who have given similar consents for use of their data.

To characterize the genetic basis of spike-wave discharges (SWDs) detected by electroencephalography (EEG) in C3H/He mice, substrains of C3H mice were evaluated by EEG and sensitivity to ethosuximide. Crosses with the SWD-negative strain C57BL/6J were performed to map the underlying gene(s). C3H/He substrains exhibited a modest incidence (average of 19 SWDs per hour) of 7-8 Hz SWDs when at rest, compared with the C3HeB/Fe subline (four SWDs per hour). In the mapping backcross, however, many mice showed a very high incidence (50-220 SWDs per hour) throughout the recording period. SWDs were first detected at 3.5 weeks of age, were associated with behavioral arrest, were suppressed by ethosuximide, and were strongest in the cerebral cortex and thalamus. The major C3H determinant of SWDs,spkw1(spike-wave 1), mapped to chromosome (Chr 9), and together with a C57BL/6J determinant on Chr 8,spkw2, accounted for more than one-half of the phenotypic variation in the backcross mice. The modest SWD incidence in C3H/He mice and the high incidence in backcrosses implies that SWD could be a confounding variable for other behaviors. Because C3H/He mice have no other brain abnormalities, they are an attractive alternative for studying idiopathic absence epilepsy.

N-ethyl-N-nitrosourea (ENU) mutagenesis is presented as a powerful approach to developing models for human disease. The efforts of three NIH Mutagenesis Centers established for the detection of neuroscience-related phenotypes are described. Each center has developed an extensive panel of phenotype screens that assess nervous system structure and function. In particular, these screens focus on complex behavioral traits from drug and alcohol responses to circadian rhythms to epilepsy. Each of these centers has developed a bioinformatics infrastructure to track the extensive number of transactions that are inherent in these large-scale projects. Over 100 new mouse mutant lines have been defined through the efforts of these three mutagenesis centers and are presented to the research community via the centralized Web presence of the Neuromice.org consortium (http://www.neuromice.org). This community resource provides visitors with the ability to search for specific mutant phenotypes, to view the genetic and phenotypic details of mutant mouse lines, and to order these mice for use in their own research program.

The mouse has offered great promise as a model organism to study brain function and behavior; however, neurological phenotypes in mice are often detected by individual investigators in a low-throughput fashion, studying natural variants of mice or mice with spontaneous mutations or gene knockdowns. In 2000, because of the success of large-scale mutagenesis programs in other model organisms (the fruit fly Drosophila melanogaster, the nematode Caenorhabditis elegans and zebrafish) and the success of large-scale mouse mutagenesis efforts in Europe (www.mgu.har.mrc.ac.uk/mutbase/; www.gsf.de/ieg/groups/enumouse.html), the National Institutes of Health (NIH) began to support three mutagenesis centers in the US. Their collective purpose was to detect, characterize and distribute new mouse mutants with primarily neurological phenotypes. These centers are located at Northwestern University (http://genome.northwestern.edu), The Jackson Laboratory (JAX; http://nmf.jax.org) and the Tennessee Mouse Genome Consortium (TMGC; www.tnmouse.org).

The distribution of neurons immunoreactive for glutamic acid decarboxylase (GAD), the synthesizing enzyme of gamma-aminobutyric acid (GABA), was examined in the first (SI) and second (SII) somatosensory cortex of monkeys. GAD-like immunoreactive (GAD-LI) somata and puncta were present in all layers of SI and SII. All GAD-LI somata were identified as non-pyramidal neurons and were most numerous in layer IV of SI and in layer III of SII. Layer IV of SI also contained the highest density of GAD-LI puncta. In SII, GAD-LI puncta were distributed more homogeneously and did not show a dense band of labelled puncta in layer IV. The major and minor diameters of GAD-LI somata in SII ranged from 6.9 to 26.2 micron and from 6.2 to 19.0 micron, respectively. The major diameters of GAD-LI somata in SII were significantly smaller than those in SI in layers I, III and IV. Differences between the distributions of GAD-LI puncta and somata in SI and SII may be accounted for by differences in the number and/or distribution of different types of GABAergic neurons. Functional differences of neurons in SI and SII may be related to the differences in GABAergic inhibitory mechanisms and reflected in the distribution of GABAergic neurons.