A study led by an international team of researchers has made an important breakthrough in terms of understanding the causes of primary biliary cholangitis (PBC). The programme was coordinated by expects from the University of Milano-Bicocca and the Autoimmune Diseases of the Liver Centre at the San Gerardo Hospital in Monza, who have been studying this disease for many years, with collaboration from geneticists at the Humanitas Clinical Institute in Rozzano. The researchers were investigating the role played by X chromosomes in the genetic architecture of liver diseases.
As in the majority of autoimmune diseases, PBC is a pathology which disproportionately affects women to a ratio of 9 to 1 compared with men. Doctors and scientists have been studying sex hormones, such as oestrogen and progesterone, since the 1950s and 1960s in an attempt to explain the bias towards the female gender, with no clear conclusions reached. As a result, the focus of these studies was widened to include sex chromosomes too.
“For over 20 years, our group has been pioneering studies of the role of genetic and epigenetic defects in the X and Y sex chromosomes in order to explain the predominance of PBC and autoimmunity in general in females,” said Pietro Invernizzi, a Professor of Gastroenterology from the University of Milano-Bicocca. “This latest study is yet more evidence that sex chromosomes hold the key answers to this fundamental question. Now that we’ve understood that, we think we can understand why humans develop this rare liver disease and the 80 or so other autoimmune diseases, which affect a good 5 or 6% of the general population. Many of these diseases often have debilitating clinical outlooks and a scarcity of effective treatment, as in the case of rheumatoid arthritis, lupus and connective tissue disease.”