Breakpoint Junction of Interstitial Homozygous Deletion at Chromosome 2q33 in a Small Cell Lung Carcinoma

We have characterized the breakpoint junction of the homozygousdeletion at chromosome 2q33 in a small cell lung carcinoma cellline. Cloning and sequencing of the genomic regions surroundingthe breakpoint junction of the deletion revealed that the homozygousdeletion was caused by a simple interstitial deletion of a 220-kbsegment. An AT-dinucleotide of contributing germline sequenceswas overlapped at the junction. Since there were one or twonucleotide overlaps of germline sequences at breakpoint junctionsin all four cases of interstitial deletions analyzed to date,this may reflect a common mechanism underlying the occurrenceof chromosomal interstitial deletion.