Isolation of human chromosome 13-specific DNA sequences cloned from flow sorted chromosomes and potentially linked to the retinoblastoma locus.

A recombinant DNA library has been constructed using flow sorted chromosome #13 DNA and the phage vector, Charon 21A. Roughly 90% of the phage inserts in the library hybridize to human repetitive DNA. Phage containing human nonrepetitive inserts have been screened for chromosome #13 specificity by Southern blot analysis using the genomic DNA of human-rodent cell hybrids containing different regions of the human #13 autosome. Of 18 phage inserts characterized, 13 have been assigned to the 13q12----q22 subregion, three appear to be localized in the 13pter----q12 region, and two are not #13-specific. By Southern blot analysis of the DNA of a retinoblastoma patient exhibiting a deletion of band 13q14 and of karyotypically normal individuals, two phage inserts have been putatively assigned to band 13q14, the currently accepted locus for a genetic determinant for retinoblastoma. These two DNA probes show quantitative differences in hybridization band intensity in the genomic DNA of the 13q--patient relative to that of the normals. In situ hybridization data support these conclusions. A recombinant phage library that shows an approximate 90% enrichment for human chromosome #13-specific DNA fragments should prove useful not only in studies related to retinoblastoma, but also in the molecular analysis of the structure and function of chromosome #13.