Molecular analysis of the isochromosome 12P in the Pallister-Killian syndrome. Construction of a mouse-human hybrid cell line containing an i(12p) as the sole human chromosome.

An iso 12p chromosome from a patient with Pallister-Killian syndrome was successfully transferred into a mouse background by microcell-mediated chromosome transfer. The presence of the i(12p) chromosome was confirmed by karyotyping and by Southern blotting using five 12p and seven 12q probes. The isochromosome nature of the marker chromosome was confirmed by co-hydridization of a 12p probe with a 12q and an 8q probe. This cell line should be a valuable tool for physical mapping of 12p-derived DNA fragments; at the same time, it confirms the identity of the extra chromosome in the Pallister-Killian syndrome as i(12p).