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 (12,500) in 377,357 amniocentesis samples, the frequency seen (123) 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.