Disrupted-in-Schizophrenia-1 (DISC1), identified by positional cloning of a balanced translocation (1;11) with the breakpoint in intron 8 of a large Scottish pedigree, is associated with a range of neuropsychiatric disorders including schizophrenia. To model this mutation in mice, we have generated Disc1 tr transgenic mice expressing 2 copies of truncated Disc1 encoding the first 8 exons using a bacterial artificial chromosome (BAC). With this partial simulation of the human situation, we have discovered a range of phenotypes including a series of novel features not previously reported. Disc1 tr transgenic mice display enlarged lateral ventricles, reduced cerebral cortex, partial agenesis of the corpus callosum, and thinning of layers II/III with reduced neural proliferation at midneurogenesis. Parvalbumin GABAergic neurons are reduced in the hippocampus and medial prefrontal cortex, and displaced in the dorsolateral frontal cortex. In culture, transgenic neurons grow fewer and shorter neurites. Behaviorally, transgenic mice exhibit increased immobility and reduced vocalization in depression-related tests, and impairment in conditioning of latent inhibition. These abnormalities in Disc1 tr transgenic mice are consistent with findings in severe schizophrenia.

The hereditary dentine disorders, dentinogenesis imperfecta (DGI) and dentine dysplasia (DD), comprise a group of autosomal dominant genetic conditions characterised by abnormal dentine structure affecting either the primary or both the primary and secondary dentitions. DGI is reported to have an incidence of 1 in 6,000 to 1 in 8,000, whereas that of DD type 1 is 1 in 100,000. Clinically, the teeth are discoloured and show structural defects such as bulbous crowns and small pulp chambers radiographically. The underlying defect of mineralisation often results in shearing of the overlying enamel leaving exposed weakened dentine which is prone to wear.Currently, three sub-types of DGI and two sub-types of DD are recognised but this categorisation may change when other causative mutations are found. DGI type I is inherited with osteogenesis imperfecta and recent genetic studies have shown that mutations in the genes encoding collagen type 1, COL1A1 and COL1A2, underlie this condition. All other forms of DGI and DD, except DD-1, appear to result from mutations in the gene encoding dentine sialophosphoprotein (DSPP), suggesting that these conditions are allelic.

The prognosis of replanted avulsed permanent incisors depends largely on prompt and appropriate emergency management. The aim of this study was to investigate lay knowledge and attitudes in this respect. Postal questionnaires were sent to all physical education teachers, school nurses and secretaries, attendants in swimming baths and leisure centres and to 220 parents of teenage children in a defined area of North West England. The overall questionnaire response rate was 86.9%. Knowledge of methods of dealing with this problem was generally inadequate in both parents and the other groups. Although 53.6% of respondents claimed to have received first aid training only 3.1% could remember dental injuries being included. There was evidence that dental health education in this field can be effective, since the highest mean knowledge score was found in the 11.5% of respondents who recalled receiving advice from sources such as posters, magazines and newspapers. More than 80% of the respondents stated that they would not want to replant an avulsed incisor themselves, the main reason being lack of knowledge and training. It is suggested that there is a need for potentially effective dental health education in relation to this problem.

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