With respect to the liver, the lack of hepatic manifestations in most cases of AD, (hepatic steatosis has been reported in only 4 patients [8,12]) could be explained by differences in intestinal and hepatic trafficking pathways which might also use different COPII paralogues and, in particular, SAR1A for the secretion of apoB100-containing lipoproteins. Here, SAR1A is linked to fatty liver disease.