Much current research in bladder cancer is aimed at restoring chemosensitivity by shifting the cell toward a pro-apoptotic phenotype. Successful translation of this work into clinical practice may improve survival in patients in whom prognosis is currently poor.

The presence of oligoclonality has implications for the potential efficacy of novel molecular therapeutic agents for bladder cancer. The molecular targets for such therapies must be widely sampled in a tumor population to assess expression in separate clones.

We present a simple, fast, non‐radioactive method for the analysis of the polymorphic short tandem repeat (STR) system in the human phenylalanine hydroxylase gene. Previously, sizing of the STR marker involved radiolabelling of PCR amplified fragments and resolution on denaturing polyacrylamide gels using M13 sequencing ladder as a standard. However, this method consistently gave sizes 2 bp longer than the known sequence. The fluorescent method presented here employs internal lane standards and enables accurate sizing of the fragments. To avoid confusion, we suggest that the true fragment lengths are used as reference values in the future. The analysis of STR alleles is valuable for population genetic studies and for targeted mutation screening in phenylketonuria (PKU). It can replace RFLP‐based haplotype analysis for carrier detection, and we report its use for prenatal diagnosis in a Northern Irish family with PKU. The analysis of 250 Northern Irish chromosomes, including 128 PKU alleles, showed no significant difference between normal and PKU alleles, with fragment lengths of 238 and 242 bp most common in both groups.

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