What causes the female predominance of primary biliary cirrhosis (PBC) is unclear. However, the X chromosome includes genes involved in immunological tolerance.
In this study, physicians from Italy and the United States assessed the rate of X monosomy in peripheral white blood cells by fluorescence in-situ hybridisation.
They evaluated 100 women with PBC, 50 with chronic hepatitis C, and 50 healthy controls.
|Frequency of X monosomy increased with age.|
The team determined that the frequency of X monosomy increased with age in all groups, but was significantly higher in women with PBC than in the controls.
They calculated age-adjusted back-transformed mean frequencies. These were 0.050 in women with PBC, 0.032 in those with chronic hepatitis C, and 0.028 in the controls.
Dr Pietro Invernizzi's team concluded, "We suggest that haploinsufficiency for specific X-linked genes leads to female susceptibility to PBC".