Retinoblastoma, the most common intraocular
tumor, represents one of the prototypes of inheritable
cancers. To elucidate the mechanisms that give rise to this
tumor, the retinoblastoma gene (RB) must be molecularly cloned. The difficulty encountered in cloning the gene is that little of its function or structure is known. The human
esterase D gene, on the other hand, has been localized cytogenetically to the same sub-band of chromosome 13q14:11 as the RB gene. The
esterase D gene thus provides a convenient starting point for cloning the RB gene. In this communication, we describe the isolation of the
esterase D cDNA clone. Its identification is based on three lines of evidence. This
cDNA encodes a
protein immunologically related to the
esterase D protein. The deduced amino acid sequences of this clone contain sequences identical to the three CNBr-cleaved
peptides of the
esterase D protein. This clone is mapped to the chromosome 13q14 region by Southern genomic blotting using different deletion mutants. The availability of this clone should allow for the cloning of the RB gene by chromosome walking; the diagnosis of genetic defects such as
retinoblastomas and
Wilson disease, whose genes are closely linked to the
esterase D gene; and the exploration of the large family of human
esterase genes.