Subchromosomal Band Interval Mapping and Ordering of DNA Markers in the Region 3q26.3-q27 Involved in the Dup(3q) Syndrome

The duplication 3q syndrome is characterized by the partial trisomy of a segment of the long arm of chromosome 3. This segment, although variable in size, includes 3q26.3-q27 as the minimal region of overlap. We have previously used patient chromosome breakpoints to select cosmids within this region. In this report, we have used two- and three-color fluorescence in situ hybridization on metaphase and interphase chromosomes to perform high-resolution cytological mapping of the six cosmids identified. The results allowed us to determine the centromere-telomere orientation, the order, and the relative distances of the markers used. Because some of the markers used are part of the consensus chromosome 3 map, our data can be easily integrated with existing mapping information about this chromosome. Our data provide a framework for further physical mapping studies of this region.