The evidence of maternal microchimerism in biliary atresia using fluorescent in situ hybridization

Background: Biliary atresia (BA) is a cholestatic disease of unknown etiology. It has recently been suggested that graft-vs-host disease caused by microchimerism is an etiology in the development of autoimmune disease. Moreover, the liver is a frequent target organ of graft-vs-host disease. The aim of this study is to identify the presence and extent of maternal microchimerism and to determine whether it plays a role in the etiology of BA. Methods: The liver biopsy specimens of 6 male patients with BA (BA group) and 6 males with other liver diseases (non-BA group) were assayed for X- and Y-chromosome using fluorescent in situ hybridization. The cells with 2 sex chromosomes in the nuclei were counted. Cells with 1 X- and 1 Y-chromosomes were considered to be host cells, and those with 2 X-chromosome were considered to be of maternal origin. Results: The frequency of cells with XX chromosomes per 1000 host cells in the BA group and the non-BA group were 3.00 ± 0.75 and 0.99 ± 0.50, respectively (P = .005). Moreover, the age at the time of biopsy did not affect the number of chimeric cells. Conclusion: The presence of female cells in the liver of male patients with BA was significantly higher than in males with other liver disease. Maternal microchimerism is therefore suggested to contribute to the pathogenesis of BA.