The Social Communication Questionnaire (SCQ) is a parent report screening measure for autism spectrum disorders (ASDs) based on the Autism Diagnostic Interview-Revised (ADI-R). To examine its validity in a young sample, the SCQ was given to parents of 151 children at a mean age of 5 years, before assessment in tertiary autism or preschool clinics. Overall sensitivity was .71, the same for both clinics, but specificity was better for the preschool clinic (.62) than for the autism clinic (.53) reflecting fewer false-positives in the former. The "hit rate" was 65% with 28% of the children with autism missed by the SCQ at a cutoff score of 15 (false-negatives) and 38% of the nonautistic misidentified as having an ASD (false-positives). Item validity analysis, contrary to what was previously published, indicated that only 15 or 46% of the items distinguished between children with and without ASD in this much younger sample. False-negatives were somewhat higher functioning. The SCQ would seem to be a useful tool for identifying young children in need of further assessment and assisting in routing them to the appropriate clinic, especially if used in conjunction with a screening by a community professional. There remain questions about the "best" cutoff score to use and whether a shorter version, based on the items that distinguished autistic from nonautistic, would be more reliable and valid with younger children. Furthermore, it may be that an adjusted score is required when parents omit items or with nonverbal children who cannot be scored on some of the items.

Screening measures to identify very young children at risk for autism spectrum disorders include the Modified Checklist for Autism in Toddlers (M-CHAT) and the Social Communication Questionnaire (SCQ). To examine the validity of these written questionnaires, parents completed them prior to their child's diagnostic assessment at a tertiary autism clinic. The M-CHAT was given to 84 parents of 2- to 3-year-olds and the SCQ to 94 parents of 4- to 6-year-olds. On both measures sensitivity was higher than specificity with positive predictive values 0.63-0.68. False negatives, or children with autism who were missed by screening, were somewhat higher functioning than true positives. Results were better for parents who spoke English as a second language, contrary to expectations. At this stage of development these tools would be recommended as part of more comprehensive surveillance programmes to identify children in need of further assessment but not to 'screen out' the possibility of autism.

Non-subspecies I salmonellae are commensals of cold-blooded vertebrates and cause sporadic disease in mammals. The reasons why non-subspecies I salmonellae do not circulate in populations of warm-blooded vertebrates, but instead only cause occasional disease in this niche, are unknown. We examined the ability of Salmonella enterica subsp. IIIa (subsp. arizonae) and subsp. IIIb (subsp. diarizonae) isolates to grow competitively with subspecies I (serovar Typhimurium) ATCC 14028 in vitro, to colonize Salmonella-sensitive BALB/c mice, and to persist in the intestine of Salmonella-resistant CBA/J mice in competitive infections. Subspecies IIIa had severely reduced intestinal colonization, intestinal persistence, and systemic spread in mice. Subspecies IIIa is nonmotile on swarming agar and thus may also have reduced motility under viscous conditions in vivo. Surprisingly, subspecies IIIb colonizes the intestinal tract of BALB/c mice normally yet does not spread systemically. Subspecies IIIb colonization of the intestine of CBA/J mice is reduced late in infection. In order to understand why these isolates do not colonize systemic sites, we determined that subspecies IIIa and IIIb are not internalized well and do not replicate in J774-A.1 murine macrophages, despite normal adherence to these cells. We further show that selected effectors of both type III secretion systems 1 and 2 are secreted by subspecies IIIa and IIIb in vitro but that each of these isolates secretes a different combination of effectors. We outline the phenotypic differences between these subspecies and subspecies I and provide a possible explanation for the inability of these strains to spread systemically in murine models.

Autism spectrum disorders (ASDs) are a group of neurodevelopmental disorders with a strong genetic aetiology. In approximately 1% of cases, duplication of the 15q11-13 region has been reported. We report the clinical, array-comparative genomic hybridization (CGH) and cytogenetic evaluation of two individuals from a multiplex family demonstrating autism due to a maternally inherited gain of 15q11-13. Our findings indicate that unlike most 15q11-13 gains, which are caused by interstitial duplication of this region or supernumerary marker chromosomes deriving from proximal 15q, the 15q gain in this family is the result of abnormal segregation of a cryptic familial translocation with breakpoints at 14q11.2 and 15q13.3. The affected members of this family were found to have a normal karyotype at >550 band resolution. This translocation was identified using the 1-Mb resolution whole genome array (Spectral Genomics). The affected individuals have a gain of seven clones from proximal 15q, a loss of two clones from proximal 14q and a gain of two clones from 6q. Fluorescent in situ hybridization (FISH) analysis with clones from chromosomes 14 and 15, combined with DAPI reverse banding, showed an abnormal karyotype with one normal chromosome 15 and the der(15) t(14;15)(q11.2.;q13.3), resulting in the gain of proximal 15q and the loss of proximal 14q in affected individuals. The duplication of two clones from 6q in the affected subjects was also found in unaffected members of the family. Our findings suggest that the gain of 15q in autism may in some cases be due to cryptic translocations with breakpoints in the pericentromic regions of chromosome 15 and a different acrocentric chromosome. Variation in the size of pericentromic regions of any acrocentric chromosome may justify karyotype and FISH studies of autistic probands and their parents using probes from the 15q proximal region to determine recurrence risk for autism in some families.