A technique for the identification of segmental trisomy progeny in the Ts65DN mouse (an additional mouse model of Down syndrome) using inter- phase FISH of tail fibroblasts

quires some expertise in cytogenetics. A technique for the identification of segmental trisomy progeny in the Ts65DN mouse (an additional mouse model of Down syndrome) using interphase FISH of tail fibroblasts has also been reported (21). Our procedure, though similar, uses a commercially available probe generated from PCRamplified DNA from FACS-sorted chromosomes (Certificate of Analysis Information for Mouse Chromosome 16-specific Paint; Cambio). Whole chromosome paints for murine chromosomes 1–19, X and Y are also commercially available for use in detection of chromosomal abnormalities in mice (http://www.cambio.co.uk). The recent sequencing of human chromosome 21 provides great impetus for research on the molecular basis of Down syndrome (10). Due to the partial synteny between mouse chromosome 16 and human chromosome 21, the Ts 16 mouse has been used as a model for the study of aspects of this syndrome (4,6,8,12,13,19). Although the Ts 16 mouse used in the present studies exhibits perinatal mortality, it provides a valuable animal model to examine aspects of the Down syndrome phenotype such as aberrant craniofacial development. Mouse chromosome 16 has partial synteny with human 22q11, a region implicated in DiGeorge syndrome (14). Cardiac defects in the Ts 16 mouse also make it useful in the study of the formation of the atrioventricular junctions and atrial and ventricular septation (22). Analysis of aberrant gene expression in the tissues affected in these syndromes and defects will likely contribute to our understanding of the molecular and cellular basis of the associated malformations.