Genetically meaningful phenotypic subgroups in autism spectrum disorders

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder with strong evidence for genetic susceptibility. However, the effect sizes for implicated chromosomal loci are small, hard to replicate and current evidence does not explain the majority of the estimated heritability. Phenotypic heterogeneity could be one phenomenon complicating identification of genetic factors. We used data from the Autism Diagnostic Interview‐Revised, Autism Diagnostic Observation Schedule, Vineland Adaptive Behavior Scales, head circumferences, and ages at exams as classifying variables to identify more clinically similar subgroups of individuals with ASD. We identified two distinct subgroups of cases within the Autism Genetic Resource Exchange dataset, primarily defined by the overall severity of evaluated traits. In addition, there was significant familial clustering within subgroups (odds ratio, OR ≈ 1.38–1.42, P < 0.00001), and genotypes were more similar within subgroups compared to the unsubgrouped dataset (Fst = 0.17 ± 0.0.0009). These results suggest that the subgroups recapitulate genetic etiology. Using the same approach in an independent dataset from the Autism Genome Project, we similarly identified two distinct subgroups of cases and confirmed this severity‐based dichotomy. We also observed evidence for genetic contributions to subgroups identified in the replication dataset. Our results provide more effective methods of phenotype definition that should increase power to detect genetic factors influencing risk for ASD .     

Extraction and characterization ofStaphylococcus aureus h2 antigen

Staphylococcus aureus antigen h₂, one of the few heat-stable type antigens of this bacteria, has been extracted from bacteria by autolysis and purified by alcohol precipitation, ion exchange chromatography, and gel filtration. Purified h₂ is a precipitating antigen, reacting neither with antisera against α and β ribitol teichoic acids, nor with antisera against Staphylococcal lipoteichoic acid. Infrared spectrometry and chemical analysis reveal a teichoic acidlike composition with glycerol, phosphorus, N-acetylated glucosamine, and alanine as major constituents. These findings confirm the validity of the Oeding-Haukenes scheme of serotyping.     

Seasonal patterns of muscle RNA-DNA ratio and growth in black crappie,Pomoxis nigromaculatus

Synopsis Black crappie (Pomoxis nigromaculatus) were collected weekly from a natural lake during the period mid-April to mid-September. The fish were weighed, state of maturity determined and RNA-DNA ratio of white muscle was measured. Water temperature and primary production were measured in the lake. RNA-DNA ratio declined during the spawning season, reaching a low in mid-May, then increased steadily during the remainder of the year. RNA-DNA ratio was significantly correlated with body weight. The correlation was improved if RNA-DNA ratio was paired with weight for the following week. The correlation was further improved when the spawning season was removed from the data set. Both weight and RNA-DNA ratios were significantly correlated with water temperature, as expected. The correlations were again improved if water temperature was paired with weight and RNA-DNA values for the following week. Weight and RNA-DNA ratio were also correlated with primary production when the correlation was made with concurrent values, and the correlations were improved when RNA-DNA ratio or weight were paired with primary production values for the previous month. RNA-DNA ratio was determined to be a useful predictor of skeletal muscle growth in natural populations of fish over short (ca. one week) time intervals.