Studies on the absorptive defect for triglyceride in abetalipoproteinemia.

The nature of the gastrointestinal absorptive defect for triglyceride in three subjects with abetalipoproteinemia has been investigated by studying peroral biopsies of the gastrointestinal mucosa. The following conclusions were reached.1) In confirmation of other studies, the abnormal vacuoles within the duodenal absorptive cells of these individuals were lipophilic.2) On chemical analysis there was significantly more mucosal lipid than found in normal fasting specimens, and almost the entire increase was due to triglyceride.3) This excess mucosal lipid was reduced by a low fat diet, but even after 34 days on such a diet there was still an excess of lipophilic material near the villus tip and increased quantities of total lipid and triglyceride when compared with material from normal subjects similarly treated.4) Although there are demonstrable qualitative changes in mucosal and plasma lipids after an acute fat load, they are not quantitatively as great as in normal individuals. Fat balance studies and the qualitative changes in plasma and tissue lipids that do occur after more extended periods on different types of dietary fat do indicate that a considerable percentage of the dietary fat is assimilated. The route by which it is absorbed remains to be clarified.