23 Feb 2000

The Ts65Dn mouse developed at the Jackson Laboratory in Bar Harbor, Maine, has the signature skull and facial deformities of Down's syndrome, strengthening its case as a model for the human syndrome, according to report at the recent AAAS meeting in Washington, DC, Roger Reeves and his associates at Johns Hopkins had previously shown that the mouse has cerebellar deformities in parallel with human Down's syndrome, as well as learning and behavior deficits.

Down's syndrome in humans is marked by three copies of chromosome 21. The mouse model has three copies of its chromosome 16, which is virtually identical to human chromosome 21. In the study presented in Washington (and also published in the January issue of Developmental Dynamics), the researchers found the same pattern of lengthening and shortening of skull and facial bones-leading to skulls flattened at the back and shorter nose--as that found in humans with Down's syndrome.

Down's syndrome is of interest to Alzheimer's researchers because people with the syndrome eventually develop plaques and tangles such as those seen in Alzheimer's. However, this pathology has not been found in the Ts65Dn mouse. "We used three stains and several plaque-specific antibodies, but identified no corresponding pathology in mice up to three years old (that's a VERY old mouse!)," writes Reeve in an email to the Alzheimer Forum.—Hakon Heimer