nasser ebrahimi daryani department of gastroenterology and hepatology, tehran university of medical sciences, tehran, ir iran seyed moayed alavian baqiyatallah research center for gastroenterology and liver disease, baqiyatallah university of medical sciences, tehran, ir iran; middle east liver disease center (meld), tehran, ir iran; baqiyatallah university of medical sciences, tehran, ir iran. tel: +98-2188945187, fax: +98-2188945186 mohammad hossein somi research center for gastroenterology and liver disease, tabriz university of medical sciences, tabriz, ir iran mohammad torabi-nami school of advanced medical science and technologies, shiraz university of medical sciences, shiraz, ir iran