A polymorphic marker for the human cathepsin B gene.

Human cathepsin B (CTSB) is a proteolytic enzyme implicated in tumor invasion and metastasis. We describe a PCR-based polymorphic marker for this gene comprising two amplimers differing in length by 19 consecutive nucleotides in intron 7, near the exon 8 splice acceptor site, identifying two gene alleles (A and B). Allele frequencies were 0.614 for A and 0.386 for the B allele, with an observed heterozygosity of 0.457 in a cohort of 70 non-related Australian blood donors. One additional nucleotide difference was also revealed through sequencing. The human CTSB gene is located on chromosome 8 and the alleles described here can potentially be used as markers in linkage and association studies of cancers and other diseases.