CYTOGENETICS OF MULTIPLE ENDOCRINE NEOPLASIA SYNDROMES .3. ANALYSIS OF AN INSULINOMA FROM A SUBJECT WITH MEN-1 BY CHROMOSOME PAINTING

The cytogenetics of an insulinoma from a subject with MEN 1 characteri zed by the consistent presence of double minute chromosomes (dmins) an d by five characteristic marker chromosomes was investigated with fluo rescence in situ hybridization after labeling with a chromosome 11 lib rary. The dmins were consistently negative for 11q material, with the exception of one metaphase which had two positive dmins. This indicate d that the dmins are not derived massively from chromosome 11 and that they can be heterogeneous in their origin. One of the marker chromoso mes, tentatively identified as a del (7), turned out to be the product of a 7;11 translocation.