A novel strategy for the investigation of clonality in precancerous disease states and early stages of tumor progression.

A novel strategy for clonality determination from only 100 cells using the polymerase chain reaction in amplifying a 511 bp region located within the first intron of the human hypoxanthine phosphoribosyl transferase (HPRT) gene has been devised. The strategy rests on several observations: that this region in females contains two HpaII/MspI sites whose methylation remains both obligate with X chromosome inactivation and independent of tumor progression; and that this region contains single base allelic polymorphisms in 5-10% of females which can be detected by denaturing gradient gel electrophoresis (DGGE) on the PCR product. In polymorphic individuals, multiple bands (homo- and heteroduplexes) indicate multiclonality, single bands indicate monoclonality, and their comparative migrations indicate clonal identity/non-identity.