Administrator blindness affects the recording of eyewitness lineup outcomes.

OBJECTIVE: We investigated the effects of administrator knowledge of suspect identity in a lineup (blind vs. nonblind), witness identification (suspect vs. filler), and witness confidence (high vs. low) on whether administrators recorded the identification as an affirmative response; whether administrators recorded qualitative notes regarding the lineup task; and the content of those qualitative notes. HYPOTHESES: We predicted that nonblind administrators would record more identifications of the suspect than the filler, but blind administrators would record such identifications at comparable rates. We predicted this difference would be larger in the low (vs. high) confidence condition. We examined effects on administrators' qualitative notes in an exploratory fashion. METHOD: Undergraduate participant administrators (N = 488) presented a lineup to a confederate witness (who made a scripted identification decision) and completed a record of the lineup task. RESULTS: Nonblind administrators recorded 25% fewer identifications of fillers (vs. suspects), and evaluated witnesses less favorably in the filler (vs. suspect) identification condition (ηp² = .194). Blind administrators were not influenced by witness selection. Blind (vs. nonblind) administrators recorded more qualitative notes, confidence statements, and information relevant to witnesses' decision processes, regardless of whether witnesses identified the suspect or the filler. Among those who recorded a confidence statement, nonblind administrators' characterizations were biased such that independent coders judged witnesses to be more confident in their identifications of the suspect (vs. filler). CONCLUSION: Blind administration eliminates numerous biases associated with administrator expectations and may yield more informative lineup records. These results further support blind lineup reform recommendations. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Exome sequencing reveals pathogenic mutations in 91 strains of mice with Mendelian disorders.

Spontaneously arising mouse mutations have served as the foundation for understanding gene function for more than 100 years. We have used exome sequencing in an effort to identify the causative mutations for 172 distinct, spontaneously arising mouse models of Mendelian disorders, including a broad range of clinically relevant phenotypes. To analyze the resulting data, we developed an analytics pipeline that is optimized for mouse exome data and a variation database that allows for reproducible, user-defined data mining as well as nomination of mutation candidates through knowledge-based integration of sample and variant data. Using these new tools, putative pathogenic mutations were identified for 91 (53%) of the strains in our study. Despite the increased power offered by potentially unlimited pedigrees and controlled breeding, about half of our exome cases remained unsolved. Using a combination of manual analyses of exome alignments and whole-genome sequencing, we provide evidence that a large fraction of unsolved exome cases have underlying structural mutations. This result directly informs efforts to investigate the similar proportion of apparently Mendelian human phenotypes that are recalcitrant to exome sequencing.

A missense mutation in Grm6 reduces but does not eliminate mGluR6 expression or rod depolarizing bipolar cell function.

GRM6 encodes the metabotropic glutamate receptor 6 (mGluR6) used by retinal depolarizing bipolar cells (DBCs). Mutations in GRM6 lead to DBC dysfunction and underlie the human condition autosomal recessive complete congenital stationary night blindness. Mouse mutants for Grm6 are important models for this condition. Here we report a new Grm6 mutant, identified in an electroretinogram (ERG) screen of mice maintained at The Jackson Laboratory. The Grm6nob8 mouse has a reduced-amplitude b-wave component of the ERG, which reflects light-evoked DBC activity. Sequencing identified a missense mutation that converts a highly conserved methionine within the ligand binding domain to leucine (p.Met66Leu). Consistent with prior studies of Grm6 mutant mice, the laminar size and structure in the Grm6nob8 retina were comparable to control. The Grm6nob8 phenotype is distinguished from other Grm6 mutants that carry a null allele by a reduced but not absent ERG b-wave, decreased but present expression of mGluR6 at DBC dendritic tips, and mislocalization of mGluR6 to DBC somas. Consistent with a reduced but not absent b-wave, there were a subset of retinal ganglion cells whose responses to light onset have times to peak within the range of those in control retinas. These data indicate that the p.Met66Leu mutant mGluR6 is trafficked less than control. However, the mGluR6 that is localized to the DBC dendritic tips is able to initiate DBC signal transduction. The Grm6nob8 mouse extends the Grm6 allelic series and will be useful for elucidating the role of mGluR6 in DBC signal transduction and in human disease.NEW & NOTEWORTHY This article describes a mouse model of the human disease complete congenital stationary night blindness in which the mutation reduces but does not eliminate GRM6 expression and bipolar cell function, a distinct phenotype from that seen in other Grm6 mouse models.

Impact of elimination diets on growth and nutritional status in children with multiple food allergies.

BACKGROUND: Impairment of growth has been reported in food-allergic children. It is not known whether this is related to the extent of food allergies. We sought to compare growth, nutritional status, and nutrient intake in children with food allergy either avoiding cow's milk or avoiding cow's milk and wheat, which are staples of the diet in young children. METHODS: Infants and young children with challenge-proven allergy were recruited to this prospective study. They were strictly avoiding their allergic food triggers, either cow's milk, or cow's milk and wheat. They were counseled by a dietitian specialized in food allergies on food avoidance diets and nutritionally adequate supplementation at regular intervals. A 3-day food diary was kept. Children's height, weight, and laboratory data for nutritional parameters were monitored at 8-month intervals. RESULTS: A total of 18 patients avoiding milk and 28 patients avoiding milk and wheat were evaluated at an average of 12, 21, and 28 months of age. During the follow-up, the markers of nutritional status, nutrient intake or height for age, and weight for height were comparable between the two groups, although the means for anthropometric measures were below the average for age in both groups. CONCLUSIONS: The extent of food elimination diet has no impact on growth or nutritional status of food-allergic children, when diet is adequately supplemented. Close physician and dietitian follow-up are essential for food-allergic children when avoiding one or more foods, which are staples of the diet.

Witch Nails (Krt90whnl): A spontaneous mouse mutation affecting nail growth and development.

Numerous single gene mutations identified in humans and mice result in nail deformities with many similarities between the species. A spontaneous, autosomal, recessive mutation called witch nails (whnl) is described here where the distal nail matrix and nail bed undergo degenerative changes resulting in formation of an abnormal nail plate causing mice to develop long, curved nails. This mutation arose spontaneously in a colony of MRL/MpJ-Faslpr/J at The Jackson Laboratory. Homozygous mutant mice are recognizable by 8 weeks of age by their long, curved nails. The whnl mutation, mapped on Chromosome 15, is due to a 7-bp insertion identified in the 3' region of exon 9 in the Krt90 gene (formerly Riken cDNA 4732456N10Rik), and is predicted to result in a frameshift that changes serine 476 to arginine and subsequently introduces 36 novel amino acids into the protein before a premature stop codon (p. Ser476ArgfsTer36). By immunohistochemistry the normal KRT90 protein is expressed in the nail matrix and nail bed in control mice where lesions are located in mutant mice. Immunoreactivity toward equine KRT124, the ortholog of mouse KRT90, is restricted to the hoof lamellae (equine hoof wall and lamellae are homologous to the mouse nail plate and nail bed) and the mouse nail bed. Equine laminitis lesions are similar to those observed in this mutant mouse suggesting that the latter may be a useful model for hoof and nail diseases. This first spontaneous mouse mutation affecting the novel Krt90 gene provides new insight into the normal regulation of the molecular pathways of nail development.

Fierce: a new mouse deletion of Nr2e1; violent behaviour and ocular abnormalities are background-dependent.

A new spontaneous mouse mutation named fierce (frc) is deleted for the nuclear receptor Nr2e1 gene (also known as Tlx, mouse homolog of Drosophila tailless). The fierce mutation is genetically and phenotypically similar to Nr2e1 targeted mutations previously studied on segregating genetic backgrounds. However, we have characterized the fierce brain, eye, and behavioural phenotypes on three defined genetic backgrounds (C57BL/6J, 129P3/JEms, and B6129F1). The data revealed many novel and background-dependent phenotypic characteristics. Whereas abnormalities in brain development, hypoplasia of cerebrum and olfactory lobes, were consistent on all three backgrounds, our novel finding of enlarged ventricles in 100% and overt hydrocephalus in up to 30% of fierce mice were unique to the C57BL/6J background. Developmental eye abnormalities were also background-dependent with B6129F1-frc mice having less severe thinning of optic layers and less affected electroretinogram responses. Impaired regression of hyaloid vessels was observed in all backgrounds. Furthermore, retinal vessels were deficient in size and number in 129P3/JEms-frc and B6129F1-frc mice but almost entirely absent in C57BL/6J-frc mice. We present the first standardized behavioural tests conducted on Nr2e1 mutant mice and show that C57BL/6J-frc and B6129F1-frc mice have deficits in sensorimotor assays and are hyperaggressive in both sexes and backgrounds. However, C57BL/6J-frc mice were significantly more aggressive than B6129F1-frc mice. Overall, this extensive characterization of the fierce mutation is essential to its application for the study of behavioural, and brain and eye developmental disorders. In addition, the background-dependent differences revealed will enable the identification of important genetic modifiers.