Structural analysis of the polymorphic 3– region of the human chorionic gonadotropin-α gene in normal placenta and choriocarcinoma cells

We previously examined the segregation patterns of two polymorphic restriction enzyme sites for EcoRI and Hindlll in the 3–-flanking region of human CG-α gene in placenta and choriocarcinoma. We observed that a unique combination of restriction sites predominates in choriocarcinoma while this pattern was rare in placenta, suggesting a functionally important site in this region of genome. These data indicate that major DNA rearrangements in the 3– region of the gene are not associated with choriocarcinoma. However, analysis of the polymorphic sites revealed that there is a linkage disequilibrium among these sites which may extend to a putative oncogene which is responsible for developing choriocarcinoma.