A SUBSET OF GESTATIONAL TROPHOBLASTIC DISEASE CHARACTERIZED BY ABNORMAL CHROMOSOME-8 COPY NUMBER DETECTED BY FLUORESCENCE IN-SITU HYBRIDIZATION

The present paper describes the results of research conducted to ascer tain whether the report by Mark et al. [1], describing the concurrence of congenital trisomy 8 mosaicism and gestational trophoblastic disea se (GTD) in a 42 year-old Gravida IV, Para IV patient was an isolated event. In contrast to other cases described in the literature, the pat ient described in Mark et al. [1] had no additional confounding chromo sonal abnormalities other than trisomy 8. To the best of our knowledge , ours was the only reported case of constitutional trisomy 8 mosaicis m associated with gestational trophoblastic disease, a rare gynecologi cal disease entity. The question arises whether there exists a subset of patients with GTD characterized by an abnormal chromosome 8 copy nu mber. The implicit hypothesis is that an abnormal number of chromosome 8 somehow predisposes to cancer. A pilot study of 10 cases of GTD was conducted using fluorescence in situ hybridization (FISH) and a comme rcial chromosome 8-specific alpha-satellite probe on formalin-fixed, p araffin-embedded patient tissues. Among eight informative cases succes sfully completed, two cases (25%) were found to be trisomic, when a cu t-off point of 10% trisomic cells is adopted. Another two cases (Z5%) were found to be triploid. The results of our FISH study indicated tha t an abnormal chromosome 8 copy number found in Mark et al, [4] is unl ikely to be an isolated event. Our data are consistent with the hypoth esis that a subset of GTD indeed may exist which is characterized by m ore than two copies of chromosome 8. The present findings corroborate those recently found in breast, prostate, and other cancers, (C) Elsev ier Science Inc., 1997.