Amplification or rearrangement of the beta-human chorionic gonadotrophin (beta-hCG)--human LH gene cluster is not responsible for the ectopic production of beta-hCG by bladder tumour cells.

The beta-subunit of human chorionic gonadotrophin (hCG) is coded on chromosome 19 by the beta-hCG-hLH gene cluster. Genomic DNA has been isolated from bladder tumour cell lines which ectopically express beta-hCG. The beta-hCG-hLH gene cluster was probed for possible rearrangement or amplification and cells karyotyped for chromosome 19 abnormalities. No rearrangement or amplification of the gene cluster and no consistent abnormalities of chromosome 19 were found. The expression of beta-hCG by bladder tumours is therefore likely to be the result of altered gene regulation and not a rearrangement or amplification of this gene cluster.