Supernumerary marker chromosomes in peripheral blood cells of hepatitis B virus chronic carriers.

Cytogenetic analysis of metaphase chromosome spreads from peripheral blood cells of hepatitis B virus (HBV) chronic carriers revealed supernumerary marker chromosomes in 2 of the 46 individuals tested. Both individuals are phenotypically normal oriental males, and exhibit mosaicism with a 46,XY/47,XY,+mar/48,XY,+2mar profile in one, and a 46,XY/47,XY,+mar profile in other. Based on the reported frequency of unidentified supernumerary chromosomes (1:2,500) in 377,357 amniocentesis samples, the frequency seen (1:23) in the population of HBV chronic carriers sampled here appears unusually high. The possibility of a role for HBV in the generation of marker chromosomes is discussed.