Previous research has hypothesized an association between Alzheimer's disease and the amyloid precursor protein (APP) gene found on chromosome 21. We report the case of a 78-year-old woman with Down's syndrome with partial trisomy 21 [46,XX,rec(21)dup q, inv(21) (p12q22.1)]. No evidence of Alzheimer's disease was found on neuropsychological, magnetic resonance imaging, and neuropathological assessment. The gene sequence for APP was present in only two copies. This case further supports the hypothesis that Alzheimer's disease is associated with trisomy for proximal chromosome 21q, including the APP gene.

No abstract

No abstract

We have analysed 22 nasopharyngeal carcinomas (NPCs) for expression of the small nuclear Epstein-Barr virus (EBV)-encoded RNAs (EBERs) and for immunohistologically detectable overexpression of p53. In situ hybridization demonstrated expression of the EBERs in 13 undifferentiated NPCs while nine squamous cell NPCs were EBER-negative. These results therefore confirm our previous DNA-DNA in situ hybridization studies and demonstrate that in the nasopharynx EBV is exclusively associated with undifferentiated but not with squamous cell carcinomas. p53 overexpression was demonstrated by immunohistology in 5 of 9 squamous cell NPCs and in 9 of 13 undifferentiated NPCs. Thus, there appears to be no correlation of p53 overexpression with EBV infection. These results are unexpected in the light of previous studies demonstrating that the p53 gene in primary undifferentiated NPC is consistently in the wild-type configuration. By contrast, analyses of squamous cell carcinomas of the head and neck have demonstrated that p53 overexpression in these cases is the result of p53 gene mutation. Whilst more detailed genetic analysis is required, our results suggest that mechanisms other than mutation of the p53 gene may be responsible for the stabilization of the protein in cases of undifferentiated NPC. It is tempting to speculate that an EBV-encoded protein may be involved.

No abstract